This article provides requirements for the following:
- Identification of terminals
- Grounded conductors in premises wiring systems
- Identification of grounded conductors
Informational Note: See Article 100 for definitions of Grounded Conductor, Equipment Grounding Conductor, and Grounding Electrode Conductor.
Grounded conductors shall comply with 200.2(A) and (B).
The grounded conductor, if insulated, shall have insulation that is (1) suitable, other than color, for any ungrounded conductor of the same circuit for systems of 1000 volts or less, or impedance grounded neutral systems of over 1000 volts, or (2) rated not less than 600 volts for solidly grounded neutral systems of over 1000 volts as described in 250.184(A).
The continuity of a grounded conductor shall not depend on a connection to a metallic enclosure, raceway, or cable armor.
Informational Note: See 300.13(B) for the continuity of grounded conductors used in multiwire branch circuits.
Premises wiring shall not be electrically connected to a supply system unless the latter contains, for any grounded conductor of the interior system, a corresponding conductor that is grounded. For the purpose of this section, electrically connected shall mean connected so as to be capable of carrying current, as distinguished from connection through electromagnetic induction.
Exception: Listed utility-interactive inverters identified for use in distributed resource generation systems such as photovoltaic and fuel cell power systems shall be permitted to be connected to premises wiring without a grounded conductor where the connected premises wiring or utility system includes a grounded conductor.
Neutral conductors shall be installed in accordance with 200.4(A) and (B).
Neutral conductors shall not be used for more than one branch circuit, for more than one multiwire branch circuit, or for more than one set of ungrounded feeder conductors unless specifically permitted elsewhere in this Code.
Where more than one neutral conductor associated with different circuits is in an enclosure, grounded circuit conductors of each circuit shall be identified or grouped to correspond with the ungrounded circuit conductor(s) by wire markers, cable ties, or similar means in at least one location within the enclosure.
Exception No. 1: The requirement for grouping or identifying shall not apply if the branch-circuit or feeder conductors enter from a cable or a raceway unique to the circuit that makes the grouping obvious.
Exception No. 2: The requirement for grouping or identifying shall not apply where branch-circuit conductors pass though a box or conduit body without a loop as described in 314.16(B)(1) or without a splice or termination.
An insulated grounded conductor of 6 AWG or smaller shall be identified by one of the following means:
- A continuous white outer finish.
- A continuous gray outer finish.
- Three continuous white or gray stripes along the conductor's entire length on other than green insulation.
- Wires that have their outer covering finished to show a white or gray color but have colored tracer threads in the braid identifying the source of manufacture shall be considered as meeting the provisions of this section.
- The grounded conductor of a mineral-insulated, metal-sheathed cable (Type MI) shall be identified at the time of installation by distinctive marking at its terminations.
- A single-conductor, sunlight-resistant, outdoor-rated cable used as a grounded conductor in photovoltaic power systems, as permitted by 690.31, shall be identified at the time of installation by distinctive white marking at all terminations.
- Fixture wire shall comply with the requirements for grounded conductor identification as specified in 402.8.
- For aerial cable, the identification shall be as above, or by means of a ridge located on the exterior of the cable so as to identify it.
An insulated grounded conductor 4 AWG or larger shall be identified by one of the following means:
- A continuous white outer finish.
- A continuous gray outer finish.
- Three continuous white or gray stripes along the conductor's entire length on other than green insulation.
- At the time of installation, by a distinctive white or gray marking at its terminations. This marking shall encircle the conductor or insulation.
An insulated conductor that is intended for use as a grounded conductor, where contained within a flexible cord, shall be identified by a white or gray outer finish or by methods permitted by 400.22.
Where grounded conductors of different systems are installed in the same raceway, cable, box, auxiliary gutter, or other type of enclosure, each grounded conductor shall be identified by system. Identification that distinguishes each system grounded conductor shall be permitted by one of the following means:
- One system grounded conductor shall have an outer covering conforming to 200.6(A) or (B).
- The grounded conductor(s) of other systems shall have a different outer covering conforming to 200.6(A) or 200.6(B) or by an outer covering of white or gray with a readily distinguishable colored stripe other than green running along the insulation.
- Other and different means of identification as allowed by 200.6(A) or (B) that will distinguish each system grounded conductor.
The means of identification shall be documented in a manner that is readily available or shall be permanently posted where the conductors of different systems originate.
The insulated grounded conductors in a multiconductor cable shall be identified by a continuous white or gray outer finish or by three continuous white or gray stripes on other than green insulation along its entire length. Multiconductor flat cable 4 AWG or larger shall be permitted to employ an external ridge on the grounded conductor.
Exception No. 1: Where the conditions of maintenance and supervision ensure that only qualified persons service the installation, grounded conductors in multiconductor cables shall be permitted to be permanently identified at their terminations at the time of installation by a distinctive white marking or other equally effective means.
Exception No. 2: The grounded conductor of a multiconductor varnished-cloth-insulated cable shall be permitted to be identified at its terminations at the time of installation by a distinctive white marking or other equally effective means.
Informational Note: The color gray may have been used in the past as an ungrounded conductor. Care should be taken when working on existing systems.
The following shall be used only for the grounded circuit conductor, unless otherwise permitted in 200.7(B) and (C):
- A conductor with continuous white or gray covering
- A conductor with three continuous white or gray stripes on other than green insulation
- A marking of white or gray color at the termination
The use of insulation that is white or gray or that has three continuous white or gray stripes for other than a grounded conductor for circuits of 50 volts or more shall be permitted only as in (1) and (2).
- If part of a cable assembly that has the insulation permanently reidentified to indicate its use as an ungrounded conductor by marking tape, painting, or other effective means at its termination and at each location where the conductor is visible and accessible. Identification shall encircle the insulation and shall be a color other than white, gray, or green. If used for single-pole, 3-way or 4-way switch loops, the reidentified conductor with white or gray insulation or three continuous white or gray stripes shall be used only for the supply to the switch, but not as a return conductor from the switch to the outlet.
- A flexible cord having one conductor identified by a white or gray outer finish or three continuous white or gray stripes, or by any other means permitted by 400.22, that is used for connecting an appliance or equipment permitted by 400.7. This shall apply to flexible cords connected to outlets whether or not the outlet is supplied by a circuit that has a grounded conductor.
Informational Note: The color gray may have been used in the past as an ungrounded conductor. Care should be taken when working on existing systems.
The identification of terminals to which a grounded conductor is to be connected shall be substantially white in color. The identification of other terminals shall be of a readily distinguishable different color.
Exception: Where the conditions of maintenance and supervision ensure that only qualified persons service the installations, terminals for grounded conductors shall be permitted to be permanently identified at the time of installation by a distinctive white marking or other equally effective means.
All devices, excluding panelboards, provided with terminals for the attachment of conductors and intended for connection to more than one side of the circuit shall have terminals properly marked for identification, unless the electrical connection of the terminal intended to be connected to the grounded conductor is clearly evident.
Exception: Terminal identification shall not be required for devices that have a normal current rating of over 30 amperes, other than polarized attachment plugs and polarized receptacles for attachment plugs as required in 200.10(B).
Receptacles, polarized attachment plugs, and cord connectors for plugs and polarized plugs shall have the terminal intended for connection to the grounded conductor identified as follows:
- Identification shall be by a metal or metal coating that is substantially white in color or by the word white or the letter W located adjacent to the identified terminal.
- If the terminal is not visible, the conductor entrance hole for the connection shall be colored white or marked with the word white or the letter W.
Informational Note: See 250.126 for identification of wiring device equipment grounding conductor terminals.
For devices with screw shells, the terminal for the grounded conductor shall be the one connected to the screw shell.
For screw shell devices with attached leads, the conductor attached to the screw shell shall have a white or gray finish. The outer finish of the other conductor shall be of a solid color that will not be confused with the white or gray finish used to identify the grounded conductor.
Informational Note: The color gray may have been used in the past as an ungrounded conductor. Care should be taken when working on existing systems.
Appliances that have a single-pole switch or a single-pole overcurrent device in the line or any line-connected screw shell lampholders, and that are to be connected by (1) a permanent wiring method or (2) field-installed attachment plugs and cords with three or more wires (including the equipment grounding conductor), shall have means to identify the terminal for the grounded circuit conductor (if any).
No grounded conductor shall be attached to any terminal or lead so as to reverse the designated polarity.
This article covers branch circuits except for branch circuits that supply only motor loads, which are covered in Article 430. Provisions of this article and Article 430 apply to branch circuits with combination loads.
Branch circuits shall comply with this article and also with the applicable provisions of other articles of this Code. The provisions for branch circuits supplying equipment listed in Table 210.2 amend or supplement the provisions in this article.
Table 210.2 Specific-Purpose Branch Circuits
| Equipment | Article | Section |
|---|---|---|
| Air-conditioning and refrigerating equipment | 440.6, 440.31, 440.32 | |
| Audio signal processing, amplification, and reproduction equipment | 640.8 | |
| Busways | 368.17 | |
| Circuits and equipment operating at less than 50 volts | 720 | |
| Central heating equipment other than fixed electric space-heating equipment | 422.12 | |
| Class 1, Class 2, and Class 3 remote-control, signaling, and power-limited circuits | 725 | |
| Cranes and hoists | 610.42 | |
| Electric signs and outline lighting | 600.6 | |
| Electric welders | 630 | |
| Electrified truck parking space | 626 | |
| Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts | 620.61 | |
| Fire alarm systems | 760 | |
| Fixed electric heating equipment for pipelines and vessels | 427.4 | |
| Fixed electric space-heating equipment | 424.3 | |
| Fixed outdoor electrical deicing and snow-melting equipment | 426.4 | |
| Information technology equipment | 645.5 | |
| Infrared lamp industrial heating equipment | 422.48, 424.3 | |
| Induction and dielectric heating equipment | 665 | |
| Marinas and boatyards | 555.19 | |
| Mobile homes, manufactured homes, and mobile home parks | 550 | |
| Motion picture and television studios and similar locations | 530 | |
| Motors, motor circuits, and controllers | 430 | |
| Pipe organs | 650.7 | |
| Recreational vehicles and recreational vehicle parks | 551 | |
| Switchboards and panelboards | 408.52 | |
| Theaters, audience areas of motion picture and television studios, and similar locations | 520.41, 520.52, 520.62 | |
| X-ray equipment | 660.2, 517.73 |
Branch circuits recognized by this article shall be rated in accordance with the maximum permitted ampere rating or setting of the overcurrent device. The rating for other than individual branch circuits shall be 15, 20, 30, 40, and 50 amperes. Where conductors of higher ampacity are used for any reason, the ampere rating or setting of the specified overcurrent device shall determine the circuit rating.
Exception: Multioutlet branch circuits greater than 50 amperes shall be permitted to supply nonlighting outlet loads on industrial premises where conditions of maintenance and supervision ensure that only qualified persons service the equipment.
Branch circuits recognized by this article shall be permitted as multiwire circuits. A multiwire circuit shall be permitted to be considered as multiple circuits. All conductors of a multiwire branch circuit shall originate from the same panelboard or similar distribution equipment.
Informational Note No. 1: A 3-phase, 4-wire, wye-connected power system used to supply power to nonlinear loads may necessitate that the power system design allow for the possibility of high harmonic currents on the neutral conductor.
Informational Note No. 2: See 300.13(B) for continuity of grounded conductors on multiwire circuits.
Each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates.
Informational Note: See 240.15(B) for information on the use of single-pole circuit breakers as the disconnecting means.
Multiwire branch circuits shall supply only line-to-neutral loads.
Exception No. 1: A multiwire branch circuit that supplies only one utilization equipment.
Exception No. 2: Where all ungrounded conductors of the multiwire branch circuit are opened simultaneously by the branch-circuit overcurrent device.
The ungrounded and grounded circuit conductors of each multiwire branch circuit shall be grouped by cable ties or similar means in at least one location within the panelboard or other point of origination.
Exception: The requirement for grouping shall not apply if the circuit enters from a cable or raceway unique to the circuit that makes the grouping obvious or if the conductors are identified at their terminations with numbered wire markers corresponding to the appropriate circuit number.
Where the premises wiring system has branch circuits supplied from more than one nominal voltage system, each ungrounded conductor of a branch circuit shall be identified by phase or line and system at all termination, connection, and splice points in compliance with 210.5(C)(1)(a) and (b).
(a) Means of Identification. The means of identification shall be permitted to be by separate color coding, marking tape, tagging, or other approved means.
(b) Posting of Identification Means. The method utilized for conductors originating within each branch-circuit panelboard or similar branch-circuit distribution equipment shall be documented in a manner that is readily available or shall be permanently posted at each branch-circuit panelboard or similar branch-circuit distribution equipment.
Where a branch circuit is supplied from a dc system operating at more than 50 volts, each ungrounded conductor of 4 AWG or larger shall be identified by polarity at all termination, connection, and splice points by marking tape, tagging, or other approved means; each ungrounded conductor of 6 AWG or smaller shall be identified by polarity at all termination, connection, and splice points in compliance with 210.5(C)(2)(a) and (b). The identification methods utilized for conductors originating within each branch-circuit panelboard or similar branch-circuit distribution equipment shall be documented in a manner that is readily available or shall be permanently posted at each branch-circuit panelboard or similar branch-circuit distribution equipment.
(a) Positive Polarity, Sizes 6 AWG or Smaller. Where the positive polarity of a dc system does not serve as the connection point for the grounded conductor, each positive ungrounded conductor shall be identified by one of the following means:
- A continuous red outer finish
- A continuous red stripe durably marked along the conductor's entire length on insulation of a color other than green, white, gray, or black
- Imprinted plus signs (+) or the word POSITIVE or POS durably marked on insulation of a color other than green, white, gray, or black, and repeated at intervals not exceeding 610 mm (24 in.) in accordance with 310.120(B)
(b) Negative Polarity, Sizes 6 AWG or Smaller. Where the negative polarity of a dc system does not serve as the connection point for the grounded conductor, each negative ungrounded conductor shall be identified by one of the following means:
- A continuous black outer finish
- A continuous black stripe durably marked along the conductor's entire length on insulation of a color other than green, white, gray, or red
- Imprinted minus signs (—) or the word NEGATIVE or NEG durably marked on insulation of a color other than green, white, gray, or red, and repeated at intervals not exceeding 610 mm (24 in.) in accordance with 310.120(B)
The nominal voltage of branch circuits shall not exceed the values permitted by 210.6(A) through (E).
In dwelling units and guest rooms or guest suites of hotels, motels, and similar occupancies, the voltage shall not exceed 120 volts, nominal, between conductors that supply the terminals of the following:
- Luminaires
- Cord-and-plug-connected loads 1440 volt-amperes, nominal, or less or less than 1/4 hp
Circuits not exceeding 120 volts, nominal, between conductors shall be permitted to supply the following:
- The terminals of lampholders applied within their voltage ratings
- Auxiliary equipment of electric-discharge lamps
- Cord-and-plug-connected or permanently connected utilization equipment
Circuits exceeding 120 volts, nominal, between conductors and not exceeding 277 volts, nominal, to ground shall be permitted to supply the following:
- Listed electric-discharge or listed light-emitting diode-type luminaires
- Listed incandescent luminaires, where supplied at 120 volts or less from the output of a stepdown autotransformer that is an integral component of the luminaire and the outer shell terminal is electrically connected to a grounded conductor of the branch circuit
- Luminaires equipped with mogul-base screw shell lampholders
- Lampholders, other than the screw shell type, applied within their voltage ratings
- Auxiliary equipment of electric-discharge lamps
- Cord-and-plug-connected or permanently connected utilization equipment
Circuits exceeding 277 volts, nominal, to ground and not exceeding 600 volts, nominal, between conductors shall be permitted to supply the following:
- The auxiliary equipment of electric-discharge lamps mounted in permanently installed luminaires where the luminaires are mounted in accordance with one of the following:
- Not less than a height of 6.7 m (22 ft) on poles or similar structures for the illumination of outdoor areas such as highways, roads, bridges, athletic fields, or parking lots
- Not less than a height of 5.5 m (18 ft) on other structures such as tunnels
- Cord-and-plug-connected or permanently connected utilization equipment other than luminaires
- Luminaires powered from direct-current systems where the luminaire contains a listed, dc-rated ballast that provides isolation between the dc power source and the lamp circuit and protection from electric shock when changing lamps.
Exception No. 1 to (B), (C), and (D): For lampholders of infrared industrial heating appliances as provided in 422.14.
Exception No. 2 to (B), (C), and (D): For railway properties as described in 110.19.
Circuits exceeding 600 volts, nominal, between conductors shall be permitted to supply utilization equipment in installations where conditions of maintenance and supervision ensure that only qualified persons service the installation.
Where two or more branch circuits supply devices or equipment on the same yoke or mounting strap, a means to simultaneously disconnect the ungrounded conductors supplying those devices shall be provided at the point at which the branch circuits originate.
Ground-fault circuit-interrupter protection for personnel shall be provided as required in 210.8(A) through (D). The ground-fault circuit-interrupter shall be installed in a readily accessible location.
Informational Note: See 215.9 for ground-fault circuit-interrupter protection for personnel on feeders.
All 125-volt, single-phase, 15- and 20-ampere receptacles installed in the locations specified in 210.8(A)(1) through (10) shall have ground-fault circuit-interrupter protection for personnel.
- Bathrooms
- Garages, and also accessory buildings that have a floor located at or below grade level not intended as habitable rooms and limited to storage areas, work areas, and areas of similar use
- Outdoors Exception to (3): Receptacles that are not readily accessible and are supplied by a branch circuit dedicated to electric snow-melting, deicing, or pipeline and vessel heating equipment shall be permitted to be installed in accordance with 426.28 or 427.22, as applicable.
- Crawl spaces — at or below grade level
- Unfinished basements — for purposes of this section, unfinished basements are defined as portions or areas of the basement not intended as habitable rooms and limited to storage areas, work areas, and the like Exception to (5): A receptacle supplying only a permanently installed fire alarm or burglar alarm system shall not be required to have ground-fault circuit-interrupter protection.Informational Note: See 760.41(B) and 760.121(B) for power supply requirements for fire alarm systems.Receptacles installed under the exception to 210.8(A)(5) shall not be considered as meeting the requirements of 210.52(G)
- Kitchens — where the receptacles are installed to serve the countertop surfaces
- Sinks — where receptacles are installed within 1.8 m (6 ft) of the outside edge of the sink
- Boathouses
- Bathtubs or shower stalls — where receptacles are installed within 1.8 m (6 ft) of the outside edge of the bathtub or shower stall
- Laundry areas
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All 125-volt, single-phase, 15- and 20-ampere receptacles installed in the locations specified in 210.8(B)(1) through (8) shall have ground-fault circuit-interrupter protection for personnel.
- Bathrooms
- Kitchens
- Rooftops
- Outdoors Exception No. 1 to (3): Receptacles on rooftops shall not be required to be readily accessible other than from the rooftop.Exception No. 2 to (3) and (4): Receptacles that are not readily accessible and are supplied by a branch circuit dedicated to electric snow-melting, deicing, or pipeline and vessel heating equipment shall be permitted to be installed in accordance with 426.28 or 427.22, as applicable.Exception No. 3 to (4): In industrial establishments only, where the conditions of maintenance and supervision ensure that only qualified personnel are involved, an assured equipment grounding conductor program as specified in 590.6(B)(2) shall be permitted for only those receptacle outlets used to supply equipment that would create a greater hazard if power is interrupted or having a design that is not compatible with GFCI protection.
- Sinks — where receptacles are installed within 1.8 m (6 ft) of the outside edge of the sink Exception No. 1 to (5): In industrial laboratories, receptacles used to supply equipment where removal of power would introduce a greater hazard shall be permitted to be installed without GFCI protection.Exception No. 2 to (5): For receptacles located in patient bed locations of general care or critical care areas of health care facilities other than those covered under 210.8(B)(1), GFCI protection shall not be required.
- Indoor wet locations
- Locker rooms with associated showering facilities
- Garages, service bays, and similar areas other than vehicle exhibition halls and showrooms
GFCI protection shall be provided for outlets not exceeding 240 volts that supply boat hoists installed in dwelling unit locations.
GFCI protection shall be provided for outlets that supply dishwashers installed in dwelling unit locations.
Branch circuits shall not be derived from autotransformers unless the circuit supplied has a grounded conductor that is electrically connected to a grounded conductor of the system supplying the autotransformer.
Exception No. 1: An autotransformer shall be permitted without the connection to a grounded conductor where transforming from a nominal 208 volts to a nominal 240-volt supply or similarly from 240 volts to 208 volts.
Exception No. 2: In industrial occupancies, where conditions of maintenance and supervision ensure that only qualified persons service the installation, autotransformers shall be permitted to supply nominal 600-volt loads from nominal 480-volt systems, and 480-volt loads from nominal 600-volt systems, without the connection to a similar grounded conductor.
Two-wire dc circuits and ac circuits of two or more ungrounded conductors shall be permitted to be tapped from the ungrounded conductors of circuits that have a grounded neutral conductor. Switching devices in each tapped circuit shall have a pole in each ungrounded conductor. All poles of multipole switching devices shall manually switch together where such switching devices also serve as a disconnecting means as required by the following:
Branch circuits for lighting and for appliances, including motor-operated appliances, shall be provided to supply the loads calculated in accordance with 220.10. In addition, branch circuits shall be provided for specific loads not covered by 220.10 where required elsewhere in this Code and for dwelling unit loads as specified in 210.11(C).
The minimum number of branch circuits shall be determined from the total calculated load and the size or rating of the circuits used. In all installations, the number of circuits shall be sufficient to supply the load served. In no case shall the load on any circuit exceed the maximum specified by 220.18.
Where the load is calculated on the basis of volt-amperes per square meter or per square foot, the wiring system up to and including the branch-circuit panelboard(s) shall be provided to serve not less than the calculated load. This load shall be evenly proportioned among multioutlet branch circuits within the panelboard(s). Branch-circuit overcurrent devices and circuits shall be required to be installed only to serve the connected load.
In addition to the number of branch circuits required by other parts of this section, two or more 20-ampere small-appliance branch circuits shall be provided for all receptacle outlets specified by 210.52(B).
In addition to the number of branch circuits required by other parts of this section, at least one additional 20-ampere branch circuit shall be provided to supply the laundry receptacle outlet(s) required by 210.52(F). This circuit shall have no other outlets.
In addition to the number of branch circuits required by other parts of this section, at least one 120-volt, 20-ampere branch circuit shall be provided to supply a bathroom receptacle outlet(s). Such circuits shall have no other outlets.
Exception: Where the 20-ampere circuit supplies a single bathroom, outlets for other equipment within the same bathroom shall be permitted to be supplied in accordance with 210.23(A)(1) and (A)(2).
Arc-fault circuit-interrupter protection shall be provided as required in 210.12(A) (B), and (C). The arc-fault circuit interrupter shall be installed in a readily accessible location.
All 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, or similar rooms or areas shall be protected by any of the means described in 210.12(A)(1) through (6):
- A listed combination-type arc-fault circuit interrupter, installed to provide protection of the entire branch circuit
- A listed branch/feeder-type AFCI installed at the origin of the branch-circuit in combination with a listed outlet branch-circuit type arc-fault circuit interrupter installed at the first outlet box on the branch circuit. The first outlet box in the branch circuit shall be marked to indicate that it is the first outlet of the circuit.
- A listed supplemental arc protection circuit breaker installed at the origin of the branch circuit in combination with a listed outlet branch-circuit type arc-fault circuit interrupter installed at the first outlet box on the branch circuit where all of the following conditions are met:
- The branch-circuit wiring shall be continuous from the branch-circuit overcurrent device to the outlet branch-circuit arc-fault circuit interrupter.
- The maximum length of the branch-circuit wiring from the branch-circuit overcurrent device to the first outlet shall not exceed 15.2 m (50 ft) for a 14 AWG conductor or 21.3 m (70 ft) for a 12 AWG conductor.
- The first outlet box in the branch circuit shall be marked to indicate that it is the first outlet of the circuit.
- A listed outlet branch-circuit type arc-fault circuit interrupter installed at the first outlet on the branch circuit in combination with a listed branch-circuit overcurrent protective device where all of the following conditions are met:
- The branch-circuit wiring shall be continuous from the branch-circuit overcurrent device to the outlet branch-circuit arc-fault circuit interrupter.
- The maximum length of the branch-circuit wiring from the branch-circuit overcurrent device to the first outlet shall not exceed 15.2 m (50 ft) for a 14 AWG conductor or 21.3 m (70 ft) for a 12 AWG conductor.
- The first outlet box in the branch circuit shall be marked to indicate that it is the first outlet of the circuit.
- The combination of the branch-circuit overcurrent device and outlet branch-circuit AFCI shall be identified as meeting the requirements for a system combination-type AFCI and shall be listed as such.
- If RMC, IMC, EMT, Type MC, or steel-armored Type AC cables meeting the requirements of 250.118, metal wireways, metal auxiliary gutters, and metal outlet and junction boxes are installed for the portion of the branch circuit between the branch-circuit overcurrent device and the first outlet, it shall be permitted to install a listed outlet branch-circuit type AFCI at the first outlet to provide protection for the remaining portion of the branch circuit.
- Where a listed metal or nonmetallic conduit or tubing or Type MC cable is encased in not less than 50 mm (2 in.) of concrete for the portion of the branch circuit between the branch-circuit overcurrent device and the first outlet, it shall be permitted to install a listed outlet branch-circuit type AFCI at the first outlet to provide protection for the remaining portion of the branch circuit.
Exception: Where an individual branch circuit to a fire alarm system installed in accordance with 760.41(B) or 760.121(B) is installed in RMC, IMC, EMT, or steel-sheathed cable, Type AC or Type MC, meeting the requirements of 250.118, with metal outlet and junction boxes, AFCI protection shall be permitted to be omitted.
Informational Note No. 1: For information on combination-type and branch/feeder-type arc-fault circuit interrupters, see UL 1699-2011. Standard for Arc-Fault Circuit Interrupters. For information on outlet branch-circuit type arc-fault circuit interupters, see UL Subject 1699A, Outline of Investigation for Outlet Branch Circuit Arc-Fault Circuit-Interrupters. For information on system combination AFCIs, see UL Subject 1699C, Outline of Investigation for System Combination Arc-Fault Circuit Interrupters.
Informational Note No. 2: See 29.6.3(5) of NFPA 72-2013, National Fire Alarm and Signaling Code, for information related to secondary power-supply requirements for smoke alarms installed in dwelling units.
Informational Note No. 3: See 760.41(B) and 760.121(B) for power-supply requirements for fire alarm systems.
In any of the areas specified in 210.12(A), where branch-circuit wiring is modified, replaced, or extended, the branch circuit shall be protected by one of the following:
- A listed combination-type AFCI located at the origin of the branch circuit
- A listed outlet branch-circuit type AFCI located at the first receptacle outlet of the existing branch circuit
All 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets installed in dormitory unit bedrooms, living rooms, hallways, closets, and similar rooms shall be protected by a listed arc-fault circuit interrupter meeting the requirements of 210.12(A)(1) through (6) as appropriate.
Each branch-circuit disconnect rated 1000 A or more and installed on solidly grounded wye electrical systems of more than 150 volts to ground, but not exceeding 600 volts phase-to-phase, shall be provided with ground-fault protection of equipment in accordance with the provisions of 230.95.
Informational Note: For buildings that contain health care occupancies, see the requirements of 517.17.
Exception No. 1: The provisions of this section shall not apply to a disconnecting means for a continuous industrial process where a nonorderly shutdown will introduce additional or increased hazards.
Exception No. 2: The provisions of this section shall not apply if ground-fault protection of equipment is provided on the supply side of the branch circuit and on the load side of any transformer supplying the branch circuit.
An outlet(s) installed for the purpose of charging electric vehicles shall be supplied by a separate branch circuit. This circuit shall have no other outlets.
Informational Note: See 625.2 for the definition of Electric Vehicle.
Guest rooms and guest suites that are provided with permanent provisions for cooking shall have branch circuits installed to meet the rules for dwelling units.
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Informational Note No. 2: See Part II of Article 430 for minimum rating of motor branch-circuit conductors.
Informational Note No. 3: See 310.15(A)(3) for temperature limitation of conductors.
Informational Note No. 4: Conductors for branch circuits as defined in Article 100, sized to prevent a voltage drop exceeding 3 percent at the farthest outlet of power, heating, and lighting loads, or combinations of such loads, and where the maximum total voltage drop on both feeders and branch circuits to the farthest outlet does not exceed 5 percent, provide reasonable efficiency of operation. See Informational Note No. 2 of 215.2(A)(1)(b) for voltage drop on feeder conductors.
Branch-circuit conductors shall have an ampacity not less than the maximum load to be served. Conductors shall be sized to carry not less than the larger of 210.19(A)(1)(a) or (b).
(a) Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the minimum branch-circuit conductor size shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load.
(b) The minimum branch-circuit conductor size shall have an allowable ampacity not less than the maximum load to be served after the application of any adjustment or correction factors.
Exception: If the assembly, including the overcurrent devices protecting the branch circuit(s), is listed for operation at 100 percent of its rating, the allowable ampacity of the branch-circuit conductors shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load.
Conductors of branch circuits supplying more than one receptacle for cord-and-plug-connected portable loads shall have an ampacity of not less than the rating of the branch circuit.
Branch-circuit conductors supplying household ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliances shall have an ampacity not less than the rating of the branch circuit and not less than the maximum load to be served. For ranges of 83/4 kW or more rating, the minimum branch-circuit rating shall be 40 amperes.
Exception No. 1: Conductors tapped from a 50-ampere branch circuit supplying electric ranges, wall-mounted electric ovens, and counter-mounted electric cooking units shall have an ampacity of not less than 20 amperes and shall be sufficient for the load to be served. These tap conductors include any conductors that are a part of the leads supplied with the appliance that are smaller than the branch-circuit conductors. The taps shall not be longer than necessary for servicing the appliance.
Exception No. 2: The neutral conductor of a 3-wire branch circuit supplying a household electric range, a wall-mounted oven, or a counter-mounted cooking unit shall be permitted to be smaller than the ungrounded conductors where the maximum demand of a range of 83/4-kW or more rating has been calculated according to Column C of Table 220.55, but such conductor shall have an ampacity of not less than 70 percent of the branch-circuit rating and shall not be smaller than 10 AWG.
Branch-circuit conductors that supply loads other than those specified in 210.2 and other than cooking appliances as covered in 210.19(A)(3) shall have an ampacity sufficient for the loads served and shall not be smaller than 14 AWG.
Exception No. 1: Tap conductors shall have an ampacity sufficient for the load served. In addition, they shall have an ampacity of not less than 15 for circuits rated less than 40 amperes and not less than 20 for circuits rated at 40 or 50 amperes and only where these tap conductors supply any of the following loads:
(a) Individual lampholders or luminaires with taps extending not longer than 450 mm (18 in.) beyond any portion of the lampholder or luminaire.
(c) Individual outlets, other than receptacle outlets, with taps not over 450 mm (18 in.) long.
(d) Infrared lamp industrial heating appliances.
(e) Nonheating leads of deicing and snow-melting cables and mats.
The ampacity of conductors shall be in accordance with 310.15 and 310.60, as applicable. Branch-circuit conductors over 600 volts shall be sized in accordance with 210.19(B)(1) or (B)(2).
The ampacity of branch-circuit conductors shall not be less than 125 percent of the designed potential load of utilization equipment that will be operated simultaneously.
For supervised installations, branch-circuit conductor sizing shall be permitted to be determined by qualified persons under engineering supervision. Supervised installations are defined as those portions of a facility where both of the following conditions are met:
- Conditions of design and installation are provided under engineering supervision.
- Qualified persons with documented training and experience in over 600-volt systems provide maintenance, monitoring, and servicing of the system.
Branch-circuit conductors and equipment shall be protected by overcurrent protective devices that have a rating or setting that complies with 210.20(A) through (D).
Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the rating of the overcurrent device shall not be less than the noncontinuous load plus 125 percent of the continuous load.
Exception: Where the assembly, including the overcurrent devices protecting the branch circuit(s), is listed for operation at 100 percent of its rating, the ampere rating of the overcurrent device shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load.
The rating or setting of the overcurrent protective device shall not exceed that specified in the applicable articles referenced in Table 240.3 for equipment.
Where connected to a branch circuit having a rating in excess of 20 amperes, lampholders shall be of the heavy-duty type. A heavy-duty lampholder shall have a rating of not less than 660 watts if of the admedium type, or not less than 750 watts if of any other type.
A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit.
Exception No. 1: A receptacle installed in accordance with 430.81(B).
Exception No. 2: A receptacle installed exclusively for the use of a cord-and-plug-connected arc welder shall be permitted to have an ampere rating not less than the minimum branch-circuit conductor ampacity determined by 630.11(A) for arc welders.
Informational Note: See the definition of receptacle in Article 100.
Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle shall not supply a total cord-and-plug-connected load in excess of the maximum specified in Table 210.21(B)(2).
Table 210.21(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle
| Circuit Rating (Amperes) | Receptacle Rating (Amperes) | Maximum Load (Amperes) |
|---|---|---|
| 15 or 20 | 15 | 12 |
| 20 | 20 | 16 |
| 30 | 30 | 24 |
Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table 210.21(B)(3), or, where rated higher than 50 amperes, the receptacle rating shall not be less than the branch-circuit rating.
Exception No. 1: Receptacles installed exclusively for the use of one or more cord-and plug-connected arc welders shall be permitted to have ampere ratings not less than the minimum branch-circuit conductor ampacity determined by 630.11(A) or (B) for arc welders.
Exception No. 2: The ampere rating of a receptacle installed for electric discharge lighting shall be permitted to be based on 410.62(C).
| Circuit Rating (Amperes) | Receptacle Rating (Amperes) |
|---|---|
| 15 | Not over 15 |
| 20 | 15 or 20 |
| 30 | 30 |
| 40 | 40 or 50 |
| 50 | 50 |
The ampere rating of a range receptacle shall be permitted to be based on a single range demand load as specified in Table 220.55.
An individual branch circuit shall be permitted to supply any load for which it is rated, but in no case shall the load exceed the branch-circuit ampere rating.
In no case shall the load exceed the branch-circuit ampere rating. A branch circuit supplying two or more outlets or receptacles shall supply only the loads specified according to its size as specified in 210.23(A) through (D) and as summarized in 210.24 and Table 210.24.
A 15- or 20-ampere branch circuit shall be permitted to supply lighting units or other utilization equipment, or a combination of both, and shall comply with 210.23(A)(1) and (A)(2).
Exception: The small-appliance branch circuits, laundry branch circuits, and bathroom branch circuits required in a dwelling unit(s) by 210.11(C)(1), (C)(2), and (C)(3) shall supply only the receptacle outlets specified in that section.
The rating of any one cord-and-plug-connected utilization equipment not fastened in place shall not exceed 80 percent of the branch-circuit ampere rating.
The total rating of utilization equipment fastened in place, other than luminaires, shall not exceed 50 percent of the branch-circuit ampere rating where lighting units, cord-and-plug-connected utilization equipment not fastened in place, or both, are also supplied.
A 30-ampere branch circuit shall be permitted to supply fixed lighting units with heavy-duty lampholders in other than a dwelling unit(s) or utilization equipment in any occupancy. A rating of any one cord-and-plug-connected utilization equipment shall not exceed 80 percent of the branch-circuit ampere rating.
A 40- or 50-ampere branch circuit shall be permitted to supply cooking appliances that are fastened in place in any occupancy. In other than dwelling units, such circuits shall be permitted to supply fixed lighting units with heavy-duty lampholders, infrared heating units, or other utilization equipment.
Branch circuits larger than 50 amperes shall supply only nonlighting outlet loads.
The requirements for circuits that have two or more outlets or receptacles, other than the receptacle circuits of 210.11(C)(1),(C)(2), and (C)(3), are summarized in Table 210.24. This table provides only a summary of minimum requirements. See 210.19, 210.20, and 210.21 for the specific requirements applying to branch circuits.
Table 210.24 Summary of Branch-Circuit Requirements
| Circuit Rating | 15A | 20A | 30A | 40A | 50A |
|---|---|---|---|---|---|
| Conductors (min. size): | |||||
| Circuit wires1 Taps | 14 | 12 | 10 | 8 | 6 |
| Fixture wires and cords — see 240.5 | 14 | 14 | 14 | 12 | 12 |
| Overcurrent Protection | 15A | 20A | 30A | 40A | 50A |
| Outlet devices: | |||||
| Lampholders permitted | Any type | Any type | Heavy duty | Heavy duty | Heavy duty |
| Receptacle rating2 | 15 max. A | 15 or 20 A | 30 A | 40 or 50 A | 50 A |
| Maximum Load | 15A | 20A | 30A | 40A | 50A |
| Permissible load | See 210.23(A) | See 210.23(A) | See 210.23(B) | See 210.23(C) | See 210.23(C) |
1These gauges are for copper conductors.
Branch circuits in each dwelling unit shall supply only loads within that dwelling unit or loads associated only with that dwelling unit.
Branch circuits installed for the purpose of lighting, central alarm, signal, communications, or other purposes for public or common areas of a two-family dwelling, a multifamily dwelling, or a multi-occupancy building shall not be supplied from equipment that supplies an individual dwelling unit or tenant space.
Receptacle outlets shall be installed as specified in 210.52 through 210.64.
Informational Note: See Informative Annex J for information regarding ADA accessibility design.
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A cord connector that is supplied by a permanently connected cord pendant shall be considered a receptacle outlet.
A receptacle outlet shall be installed wherever flexible cords with attachment plugs are used. Where flexible cords are permitted to be permanently connected, receptacles shall be permitted to be omitted for such cords.
Appliance receptacle outlets installed in a dwelling unit for specific appliances, such as laundry equipment, shall be installed within 1.8 m (6 ft) of the intended location of the appliance.
This section provides requirements for 125-volt, 15- and 20-ampere receptacle outlets. The receptacles required by this section shall be in addition to any receptacle that is:
- Part of a luminaire or appliance, or
- Controlled by a wall switch in accordance with 210.70(A)(1), Exception No. 1. or
- Located within cabinets or cupboards, or
- Located more than 1.7 m (51/2 ft) above the floor
Permanently installed electric baseboard heaters equipped with factory-installed receptacle outlets or outlets provided as a separate assembly by the manufacturer shall be permitted as the required outlet or outlets for the wall space utilized by such permanently installed heaters. Such receptacle outlets shall not be connected to the heater circuits.
Informational Note: Listed baseboard heaters include instructions that may not permit their installation below receptacle outlets.
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In every kitchen, family room, dining room, living room, parlor, library, den, sunroom, bedroom, recreation room, or similar room or area of dwelling units, receptacle outlets shall be installed in accordance with the general provisions specified in 210.52(A)(1) through (A)(4).
Receptacles shall be installed such that no point measured horizontally along the floor line of any wall space is more than 1.8 m (6 ft) from a receptacle outlet.
As used in this section, a wall space shall include the following:
- Any space 600 mm (2 ft) or more in width (including space measured around corners) and unbroken along the floor line by doorways and similar openings, fireplaces, and fixed cabinets
- The space occupied by fixed panels in exterior walls, excluding sliding panels
- The space afforded by fixed room dividers, such as freestanding bar-type counters or railings
Receptacle outlets in or on floors shall not be counted as part of the required number of receptacle outlets unless located within 450 mm (18 in.) of the wall.
Receptacles installed for countertop surfaces as specified in 210.52(C) shall not be considered as the receptacles required by 210.52(A).
In the kitchen, pantry, breakfast room, dining room, or similar area of a dwelling unit, the two or more 20-ampere small-appliance branch circuits required by 210.11(C)(1) shall serve all wall and floor receptacle outlets covered by 210.52(A), all countertop outlets covered by 210.52(C), and receptacle outlets for refrigeration equipment.
Exception No. 1: In addition to the required receptacles specified by 210.52, switched receptacles supplied from a general-purpose branch circuit as defined in 210.70(A)(1), Exception No. 1, shall be permitted.
Exception No. 2: The receptacle outlet for refrigeration equipment shall be permitted to be supplied from an individual branch circuit rated 15 amperes or greater.
The two or more small-appliance branch circuits specified in 210.52(B)(1) shall have no other outlets.
Exception No. 1: A receptacle installed solely for the electrical supply to and support of an electric clock in any of the rooms specified in 210.52(B)(1).
Exception No. 2: Receptacles installed to provide power for supplemental equipment and lighting on gas-fired ranges, ovens, or counter-mounted cooking units.
Receptacles installed in a kitchen to serve countertop surfaces shall be supplied by not fewer than two small-appliance branch circuits, either or both of which shall also be permitted to supply receptacle outlets in the same kitchen and in other rooms specified in 210.52(B)(1). Additional small-appliance branch circuits shall be permitted to supply receptacle outlets in the kitchen and other rooms specified in 210.52(B)(1). No small-appliance branch circuit shall serve more than one kitchen.
In kitchens, pantries, breakfast rooms, dining rooms, and similar areas of dwelling units, receptacle outlets for countertop spaces shall be installed in accordance with 210.52(C)(1) through (C)(5).
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A receptacle outlet shall be installed at each wall countertop space that is 300 mm (12 in.) or wider. Receptacle outlets shall be installed so that no point along the wall line is more than 600 mm (24 in.) measured horizontally from a receptacle outlet in that space. 
Exception: Receptacle outlets shall not be required on a wall directly behind a range, counter-mounted cooking unit, or sink in the installation described in Figure 210.52(C)(1).
Figure 210.52(C)(1) Determination of Area Behind a Range, or Counter-Mounted Cooking Unit or Sink.
At least one receptacle shall be installed at each island countertop space with a long dimension of 600 mm (24 in.) or greater and a short dimension of 300 mm (12 in.) or greater.
At least one receptacle outlet shall be installed at each peninsular countertop space with a long dimension of 600 mm (24 in.) or greater and a short dimension of 300 mm (12 in.) or greater. A peninsular countertop is measured from the connecting edge.
Countertop spaces separated by rangetops, refrigerators, or sinks shall be considered as separate countertop spaces in applying the requirements of 210.52(C)(1). If a range, counter-mounted cooking unit, or sink is installed in an island or peninsular countertop and the depth of the countertop behind the range, counter-mounted cooking unit, or sink is less than 300 mm (12 in.), the range, counter-mounted cooking unit, or sink shall be considered to divide the countertop space into two separate countertop spaces. Each separate countertop space shall comply with the applicable requirements in 210.52(C).
Receptacle outlets shall be located on or above, but not more than 500 mm (20 in.) above, the countertop. Receptacle outlet assemblies listed for the application shall be permitted to be installed in countertops. Receptacle outlets rendered not readily accessible by appliances fastened in place, appliance garages, sinks, or rangetops as covered in 210.52(C)(1), Exception, or appliances occupying dedicated space shall not be considered as these required outlets.
Informational Note: See 406.5(E) for requirements for installation of receptacles in countertops.
Exception to (5): To comply with the conditions specified in (1) or (2), receptacle outlets shall be permitted to be mounted not more than 300 mm (12 in.) below the countertop. Receptacles mounted below a countertop in accordance with this exception shall not be located where the countertop extends more than 150 mm (6 in.) beyond its support base.
- Construction for the physically impaired
- On island and peninsular countertops where the countertop is flat across its entire surface (no backsplashes, dividers, etc.) and there are no means to mount a receptacle within 500 mm (20 in.) above the countertop, such as an overhead cabinet
In dwelling units, at least one receptacle outlet shall be installed in bathrooms within 900 mm (3 ft) of the outside edge of each basin. The receptacle outlet shall be located on a wall or partition that is adjacent to the basin or basin countertop, located on the countertop, or installed on the side or face of the basin cabinet. In no case shall the receptacle be located more than 300 mm (12 in.) below the top of the basin. Receptacle outlet assemblies listed for the application shall be permitted to be installed in the countertop.
Informational Note: See 406.5(E) for requirements for installation of receptacles in countertops.
Outdoor receptacle outlets shall be installed in accordance with 210.52(E)(1) through (E)(3).
Informational Note: See 210.8(A)(3).
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For a one- family dwelling and each unit of a two-family dwelling that is at grade level, at least one receptacle outlet readily accessible from grade and not more than 2.0 m (61/2 ft) above grade level shall be installed at the front and back of the dwelling.
For each dwelling unit of a multifamily dwelling where the dwelling unit is located at grade level and provided with individual exterior entrance/egress, at least one receptacle outlet readily accessible from grade and not more than 2.0 m (61/2 ft) above grade level shall be installed.
Balconies, decks, and porches that are attached to the dwelling unit and are accessible from inside the dwelling unit shall have at least one receptacle outlet accessible from the balcony, deck, or porch. The receptacle outlet shall not be located more than 2.0 m (61/2 ft) above the balcony, deck, or porch walking surface.
In dwelling units, at least one receptacle outlet shall be installed in areas designated for the installation of laundry equipment.
Exception No. 1: A receptacle for laundry equipment shall not be required in a dwelling unit of a multifamily building where laundry facilities are provided on the premises for use by all building occupants.
Exception No. 2: A receptacle for laundry equipment shall not be required in other than one-family dwellings where laundry facilities are not to be installed or permitted.
For a one-family dwelling, at least one receptacle outlet shall be installed in the areas specified in 210.52(G)(1) through (3). These receptacles shall be in addition to receptacles required for specific equipment.
In each attached garage and in each detached garage with electric power. The branch circuit supplying this receptacle(s) shall not supply outlets outside of the garage. At least one receptacle outlet shall be installed for each car space.
In each accessory building with electric power.
In each separate unfinished portion of a basement.
In dwelling units, hallways of 3.0 m (10 ft) or more in length shall have at least one receptacle outlet.
As used in this subsection, the hallway length shall be considered the length along the centerline of the hallway without passing through a doorway.
Foyers that are not part of a hallway in accordance with 210.52(H) and that have an area that is greater than 5.6 m2 (60 ft2) shall have a receptacle(s) located in each wall space 900 mm (3 ft) or more in width. Doorways, door-side windows that extend to the floor, and similar openings shall not be considered wall space.
Guest rooms or guest suites in hotels, motels, sleeping rooms in dormitories, and similar occupancies shall have receptacle outlets installed in accordance with 210.52(A) and (D). Guest rooms or guest suites provided with permanent provisions for cooking shall have receptacle outlets installed in accordance with all of the applicable rules in 210.52.
In applying the provisions of 210.52(A), the total number of receptacle outlets shall not be less than the minimum number that would comply with the provisions of that section. These receptacle outlets shall be permitted to be located conveniently for permanent furniture layout. At least two receptacle outlets shall be readily accessible. Where receptacles are installed behind the bed, the receptacle shall be located to prevent the bed from contacting any attachment plug that may be installed or the receptacle shall be provided with a suitable guard.
At least one 125-volt, single-phase, 15- or 20-ampere-rated receptacle outlet shall be installed within 450 mm (18 in.) of the top of a show window for each 3.7 linear m (12 linear ft) or major fraction thereof of show window area measured horizontally at its maximum width.
A 125-volt, single-phase, 15- or 20-ampere-rated receptacle outlet shall be installed at an accessible location for the servicing of heating, airconditioning, and refrigeration equipment. The receptacle shall be located on the same level and within 7.5 m (25 ft) of the heating, air-conditioning, and refrigeration equipment. The receptacle outlet shall not be connected to the load side of the equipment disconnecting means.
Informational Note: See 210.8 for ground-fault circuit-interrupter requirements.
Exception: A receptacle outlet shall not be required at one- and two-family dwellings for the service of evaporative coolers.
At least one 125-volt, single-phase, 15- or 20-ampere-rated receptacle outlet shall be installed within 15 m (50 ft) of the electrical service equipment.
Exception: The receptacle outlet shall not be required to be installed in one-and two-family dwellings.
Lighting outlets shall be installed where specified in 210.70(A), (B), and (C).
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In dwelling units, lighting outlets shall be installed in accordance with 210.70(A)(1), (A)(2), and (A)(3).
At least one wall switch-controlled lighting outlet shall be installed in every habitable room and bathroom.
Exception No. 1: In other than kitchens and bathrooms, one or more receptacles controlled by a wall switch shall be permitted in lieu of lighting outlets.
Exception No. 2: Lighting outlets shall be permitted to be controlled by occupancy sensors that are (1) in addition to wall switches or (2) located at a customary wall switch location and equipped with a manual override that will allow the sensor to function as a wall switch.
Additional lighting outlets shall be installed in accordance with (A)(2)(a), (A)(2)(b), and (A)(2)(c).
(a) At least one wall switch-controlled lighting outlet shall be installed in hallways, stairways, attached garages, and detached garages with electric power.
(b) For dwelling units, attached garages, and detached garages with electric power, at least one wall switch-controlled lighting outlet shall be installed to provide illumination on the exterior side of outdoor entrances or exits with grade level access. A vehicle door in a garage shall not be considered as an outdoor entrance or exit.
(c) Where one or more lighting outlet(s) are installed for interior stairways, there shall be a wall switch at each floor level, and landing level that includes an entryway, to control the lighting outlet(s) where the stairway between floor levels has six risers or more.
For attics, underfloor spaces, utility rooms, and basements, at least one lighting outlet containing a switch or controlled by a wall switch shall be installed where these spaces are used for storage or contain equipment requiring servicing. At least one point of control shall be at the usual point of entry to these spaces. The lighting outlet shall be provided at or near the equipment requiring servicing.
In hotels, motels, or similar occupancies, guest rooms or guest suites shall have at least one wall switch-controlled lighting outlet installed in every habitable room and bathroom.
Exception No. 1: In other than bathrooms and kitchens where provided, one or more receptacles controlled by a wall switch shall be permitted in lieu of lighting outlets.
Exception No. 2: Lighting outlets shall be permitted to be controlled by occupancy sensors that are (1) in addition to wall switches or (2) located at a customary wall switch location and equipped with a manual override that allows the sensor to function as a wall switch.
For attics and underfloor spaces containing equipment requiring servicing, such as heating, air-conditioning, and refrigeration equipment, at least one lighting outlet containing a switch or controlled by a wall switch shall be installed in such spaces. At least one point of control shall be at the usual point of entry to these spaces. The lighting outlet shall be provided at or near the equipment requiring servicing.
This article covers the installation requirements, overcurrent protection requirements, minimum size, and ampacity of conductors for feeders supplying branch-circuit loads.
Feeder conductors shall have an ampacity not less than required to supply the load as calculated in Parts III, IV, and V of Article 220. Conductors shall be sized to carry not less than the larger of 215.2(A)(1)(a) or (b).
(a) Where a feeder supplies continuous loads or any combination of continuous and noncontinuous loads, the minimum feeder conductor size shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load.
(b) The minimum feeder conductor size shall have an allowable ampacity not less than the maximum load to be served after the application of any adjustment or correction factors.
Informational Note No. 1: See Examples D1 through D11 in Informative Annex D.
Informational Note No. 2: Conductors for feeders, as defined in Article 100, sized to prevent a voltage drop exceeding 3 percent at the farthest outlet of power, heating, and lighting loads, or combinations of such loads, and where the maximum total voltage drop on both feeders and branch circuits to the farthest outlet does not exceed 5 percent, will provide reasonable efficiency of operation.
Informational Note No. 3: See 210.19(A), Informational Note No. 4, for voltage drop for branch circuits.
Exception No. 1: If the assembly, including the overcurrent devices protecting the feeder(s), is listed for operation at 100 percent of its rating, the allowable ampacity of the feeder conductors shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load.
Exception No. 2: Grounded conductors that are not connected to an overcurrent device shall be permitted to be sized at 100 percent of the continuous and noncontinuous load.
The size of the feeder circuit grounded conductor shall not be smaller than that required by 250.122, except that 250.122(F) shall not apply where grounded conductors are run in parallel.
Additional minimum sizes shall be as specified in 215.2(A)(2) and (A)(3) under the conditions stipulated.
The feeder conductor ampacity shall not be less than that of the service conductors where the feeder conductors carry the total load supplied by service conductors with an ampacity of 55 amperes or less.
The ampacity of conductors shall be in accordance with 310.15 and 310.60 as applicable. Where installed, the size of the feeder-circuit grounded conductor shall not be smaller than that required by 250.122, except that 250.122(F) shall not apply where grounded conductors are run in parallel. Feeder conductors over 600 volts shall be sized in accordance with 215.2(B)(1), (B)(2), or (B)(3).
The ampacity of feeders supplying a combination of transformers and utilization equipment shall not be less than the sum of the nameplate ratings of the transformers and 125 percent of the designed potential load of the utilization equipment that will be operated simultaneously.
For supervised installations, feeder conductor sizing shall be permitted to be determined by qualified persons under engineering supervision. Supervised installations are defined as those portions of a facility where all of the following conditions are met:
- Conditions of design and installation are provided under engineering supervision.
- Qualified persons with documented training and experience in over 600-volt systems provide maintenance, monitoring, and servicing of the system.
Feeders shall be protected against overcurrent in accordance with the provisions of Part I of Article 240. Where a feeder supplies continuous loads or any combination of continuous and noncontinuous loads, the rating of the overcurrent device shall not be less than the noncontinuous load plus 125 percent of the continuous load.
Exception No. 1: Where the assembly, including the overcurrent devices protecting the feeder(s), is listed for operation at 100 percent of its rating, the ampere rating of the overcurrent device shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load.
Exception No. 2: Overcurrent protection for feeders between 600 to 1000 volts shall comply with Parts I through VII of Article 240. Feeders over 1000 volts, nominal, shall comply with Part IX of Article 240.
If required by the authority having jurisdiction, a diagram showing feeder details shall be provided prior to the installation of the feeders. Such a diagram shall show the area in square feet of the building or other structure supplied by each feeder, the total calculated load before applying demand factors, the demand factors used, the calculated load after applying demand factors, and the size and type of conductors to be used.
Where a feeder supplies branch circuits in which equipment grounding conductors are required, the feeder shall include or provide an equipment grounding conductor in accordance with the provisions of 250.134, to which the equipment grounding conductors of the branch circuits shall be connected. Where the feeder supplies a separate building or structure, the requirements of 250.32(B) shall apply.
Two-wire dc circuits and ac circuits of two or more ungrounded conductors shall be permitted to be tapped from the ungrounded conductors of circuits having a grounded neutral conductor. Switching devices in each tapped circuit shall have a pole in each ungrounded conductor.
Feeders supplying 15- and 20-ampere receptacle branch circuits shall be permitted to be protected by a ground-fault circuit interrupter in lieu of the provisions for such interrupters as specified in 210.8 and 590.6(A).
Each feeder disconnect rated 1000 amperes or more and installed on solidly grounded wye electrical systems of more than 150 volts to ground, but not exceeding 600 volts phase-to-phase, shall be provided with ground-fault protection of equipment in accordance with the provisions of 230.95.
Informational Note: For buildings that contain health care occupancies, see the requirements of 517.17.
Exception No. 1: The provisions of this section shall not apply to a disconnecting means for a continuous industrial process where a nonorderly shutdown will introduce additional or increased hazards.
Exception No. 2: The provisions of this section shall not apply if ground-fault protection of equipment is provided on the supply side of the feeder and on the load side of any transformer supplying the feeder.
Feeders shall not be derived from autotransformers unless the system supplied has a grounded conductor that is electrically connected to a grounded conductor of the system supplying the autotransformer.
Exception No. 1: An autotransformer shall be permitted without the connection to a grounded conductor where transforming from a nominal 208 volts to a nominal 240-volt supply or similarly from 240 volts to 208 volts.
Exception No. 2: In industrial occupancies, where conditions of maintenance and supervision ensure that only qualified persons service the installation, autotransformers shall be permitted to supply nominal 600-volt loads from nominal 480-volt systems, and 480-volt loads from nominal 600-volt systems, without the connection to a similar grounded conductor.
Where the premises wiring system has feeders supplied from more than one nominal voltage system, each ungrounded conductor of a feeder shall be identified by phase or line and system at all termination, connection, and splice points in compliance with 215.12(C)(1)(a) and (b).
(a) Means of Identification. The means of identification shall be permitted to be by separate color coding, marking tape, tagging, or other approved means.
(b) Posting of Identification Means. The method utilized for conductors originating within each feeder panelboard or similar feeder distribution equipment shall be documented in a manner that is readily available or shall be permanently posted at each feeder panelboard or similar feeder distribution equipment.
Where a feeder is supplied from a dc system operating at more than 50 volts, each ungrounded conductor of 4 AWG or larger shall be identified by polarity at all termination, connection, and splice points by marking tape, tagging, or other approved means; each ungrounded conductor of 6 AWG or smaller shall be identified by polarity at all termination, connection, and splice points in compliance with 215.12(C)(2)(a) and (b). The identification methods utilized for conductors originating within each feeder panelboard or similar feeder distribution equipment shall be documented in a manner that is readily available or shall be permanently posted at each feeder panelboard or similar feeder distribution equipment.
(a) Positive Polarity, Sizes 6 AWG or Smaller. Where the positive polarity of a dc system does not serve as the connection for the grounded conductor, each positive ungrounded conductor shall be identified by one of the following means:
- A continuous red outer finish
- A continuous red stripe durably marked along the conductor's entire length on insulation of a color other than green, white, gray, or black
- Imprinted plus signs (+) or the word POSITIVE or POS durably marked on insulation of a color other than green, white, gray, or black, and repeated at intervals not exceeding 610 mm (24 in.) in accordance with 310.120(B)
(b) Negative Polarity, Sizes 6 AWG or Smaller. Where the negative polarity of a dc system does not serve as the connection for the grounded conductor, each negative ungrounded conductor shall be identified by one of the following means:
- A continuous black outer finish
- A continuous black stripe durably marked along the conductor's entire length on insulation of a color other than green, white, gray, or red
- Imprinted minus signs (—) or the word NEGATIVE or NEG durably marked on insulation of a color other than green, white, gray, or red, and repeated at intervals not exceeding 610 mm (24 in.) in accordance with 310.120(B)
This article provides requirements for calculating branch-circuit, feeder, and service loads. Part I provides for general requirements for calculation methods. Part II provides calculation methods for branch-circuit loads. Parts III and IV provide calculation methods for feeders and services. Part V provides calculation methods for farms.
Informational Note No. 1: See examples in Informative Annex D.
Informational Note No. 2: See Figure 220.1 for information on the organization of Article 220.
Informational Note No. 2: See Figure 220.1 for information on the organization of Article 220.
In other articles applying to the calculation of loads in specialized applications, there are requirements provided in Table 220.3 that are in addition to, or modifications of, those within this article.
Table 220.3 Additional Load Calculation References
| Calculation | Article | Section (or Part) |
|---|---|---|
| Air-conditioning and refrigerating equipment, branch-circuit conductor sizing | 440 | Part IV |
| Cranes and hoists, rating and size of conductors | 610 | 610.14 |
| Electric vehicle charging system branch-circuit and feeder calculations | 625 | 625.41 |
| Electric welders, ampacity calculations | 630 | 630.11, 630.31 |
| Electrically driven or controlled irrigation machines | 675 | 675.7(A), 675.22(A) |
| Electrified truck parking space | 626 | |
| Electrolytic cell lines | 668 | 668.3(C) |
| Electroplating, branch-circuit conductor sizing | 669 | 669.5 |
| Elevator feeder demand factors | 620 | 620.14 |
| Fire pumps, voltage drop (mandatory calculation) | 695 | 695.7 |
| Fixed electric heating equipment for pipelines and vessels, branch-circuit sizing | 427 | 427.4 |
| Fixed electric space-heating equipment, branch-circuit sizing | 424 | 424.3 |
| Fixed outdoor electric deicing and snow-melting equipment, branch-circuit sizing | 426 | 426.4 |
| Industrial machinery, supply conductor sizing | 670 | 670.4(A) |
| Marinas and boatyards, feeder and service load calculations | 555 | 555.12 |
| Mobile homes, manufactured homes, and mobile home parks, total load for determining power supply | 550 | 550.18(B) |
| Mobile homes, manufactured homes, and mobile home parks, allowable demand factors for park electrical wiring systems | 550 | 550.31 |
| Motion picture and television studios and similar locations - sizing of feeder conductors for television studio sets | 530 | 530.19 |
| Motors, feeder demand factor | 430 | 430.26 |
| Motors, multimotor and combination-load equipment | 430 | 430.25 |
| Motors, several motors or a motor(s) and other load(s) | 430 | 430.24 |
| Over 600-volt branch-circuit calculations | 210 | 210.19(B) |
| Over 600-volt feeder calculations | 215 | 215.2(B) |
| Phase converters, conductors | 455 | 455.6 |
| Recreational vehicle parks, basis of calculations | 551 | 551.73(A) |
| Sensitive electrical equipment, voltage drop (mandatory calculation) | 647 | 647.4(D) |
| Solar photovoltaic systems, circuit sizing and current | 690 | 690.8 |
| Storage-type water heaters | 422 | 422.11(E) |
| Theaters, stage switchboard feeders | 520 | 520.27 |
Unless other voltages are specified, for purposes of calculating branch-circuit and feeder loads, nominal system voltages of 120, 120/240, 208Y/120, 240, 347, 480Y/277, 480, 600Y/347, and 600 volts shall be used.
Calculations shall be permitted to be rounded to the nearest whole ampere, with decimal fractions smaller than 0.5 dropped.
A unit load of not less than that specified in Table 220.12 for occupancies specified therein shall constitute the minimum lighting load. The floor area for each floor shall be calculated from the outside dimensions of the building, dwelling unit, or other area involved. For dwelling units, the calculated floor area shall not include open porches, garages, or unused or unfinished spaces not adaptable for future use.
Informational Note: The unit values herein are based on minimum load conditions and 100 percent power factor and may not provide sufficient capacity for the installation contemplated.
Exception: Where the building is designed and constructed to comply with an energy code adopted by the local authority, the lighting load shall be permitted to be calculated at the values specified in the energy code where the following conditions are met:
- A power monitoring system is installed that will provide continuous information regarding the total general lighting load of the building.
- The power monitoring system will be set with alarm values to alert the building owner or manager if the lighting load exceeds the values set by the energy code.
- The demand factors specified in 220.42 are not applied to the general lighting load.
Table 220.12 General Lighting Loads by Occupancy
| Type of Occupancy | Unit Load | |
|---|---|---|
| Volt-Amperes/Square Meter | Volt-Amperes/Square Foot | |
| Armories and auditoriums | 11 | 1 |
| Banks | 39b | 31/2b |
| Barber shops and beauty parlors | 33 | 3 |
| Churches | 11 | 1 |
| Clubs | 22 | 2 |
| Court rooms | 22 | 2 |
| Dwelling unitsa | 33 | 3 |
| Garages — commercial (storage) | 6 | 1/2 |
| Hospitals | 22 | 2 |
| Hotels and motels, including apartment houses without provision for cooking by tenantsa | 22 | 2 |
| Industrial commercial (loft) buildings | 22 | 2 |
| Lodge rooms | 17 | 11/2 |
| Office buildings | 39b | 31/2b |
| Restaurants | 22 | 2 |
| Schools | 33 | 3 |
| Stores | 33 | 3 |
| Warehouses (storage) | 3 | 1/4 |
| In any of the preceding occupancies except one-family dwellings and individual dwelling units of two-family and multifamily dwellings: | ||
Assembly halls and auditoriums |
11 | 1 |
Halls, corridors, closets, stairways |
6 | 1/2 |
Storage spaces |
3 | 1/4 |
aSee 220.14(J).
bSee 220.14(K).
In all occupancies, the minimum load for each outlet for general-use receptacles and outlets not used for general illumination shall not be less than that calculated in 220.14(A) through (L), the loads shown being based on nominal branch-circuit voltages.
Exception: The loads of outlets serving switchboards and switching frames in telephone exchanges shall be waived from the calculations.
Load calculations shall be permitted as specified in 220.54 for electric dryers and in 220.55 for electric ranges and other cooking appliances.
Outlets for heavy-duty lampholders shall be calculated at a minimum of 600 voltamperes.
Sign and outline lighting outlets shall be calculated at a minimum of 1200 voltamperes for each required branch circuit specified in 600.5(A).
Show windows shall be calculated in accordance with either of the following:
- The unit load per outlet as required in other provisions of this section
- At 200 volt-amperes per 300 mm (1 ft) of show window
Fixed multioutlet assemblies used in other than dwelling units or the guest rooms or guest suites of hotels or motels shall be calculated in accordance with (H)(1) or (H)(2). For the purposes of this section, the calculation shall be permitted to be based on the portion that contains receptacle outlets.
- Where appliances are unlikely to be used simultaneously, each 1.5 m (5 ft) or fraction thereof of each separate and continuous length shall be considered as one outlet of not less than 180 volt-amperes.
- Where appliances are likely to be used simultaneously, each 300 mm (1 ft) or fraction thereof shall be considered as an outlet of not less than 180 volt-amperes.
Except as covered in 220.14(J) and (K), receptacle outlets shall be calculated at not less than 180 volt-amperes for each single or for each multiple receptacle on one yoke. A single piece of equipment consisting of a multiple receptacle comprised of four or more receptacles shall be calculated at not less than 90 volt-amperes per receptacle. This provision shall not be applicable to the receptacle outlets specified in 210.11(C)(1) and (C)(2).
In one-family, two-family, and multifamily dwellings and in guest rooms or guest suites of hotels and motels, the outlets specified in (J)(1), (J)(2), and (J)(3) are included in the general lighting load calculations of 220.12. No additional load calculations shall be required for such outlets.
- All general-use receptacle outlets of 20-ampere rating or less, including receptacles connected to the circuits in 210.11(C)(3)
- The receptacle outlets specified in 210.52(E) and (G)
- The lighting outlets specified in 210.70(A) and (B)
In banks or office buildings, the receptacle loads shall be calculated to be the larger of (1) or (2):
- The calculated load from 220.14(I)
- 11 volt-amperes/m2 or 1 volt-ampere/ft2
Loads added to an existing dwelling unit(s) shall comply with the following as applicable:
- Loads for structural additions to an existing dwelling unit or for a previously unwired portion of an existing dwelling unit, either of which exceeds 46.5 m2 (500 ft2), shall be calculated in accordance with 220.12 and 220.14.
- Loads for new circuits or extended circuits in previously wired dwelling units shall be calculated in accordance with either 220.12 or 220.14, as applicable.
Loads for new circuits or extended circuits in other than dwelling units shall be calculated in accordance with either 220.12 or 220.14, as applicable.
The total load shall not exceed the rating of the branch circuit, and it shall not exceed the maximum loads specified in 220.18(A) through (C) under the conditions specified therein.
Where a circuit supplies only motor-operated loads, Article 430 shall apply. Where a circuit supplies only air-conditioning equipment, refrigerating equipment, or both, Article 440 shall apply. For circuits supplying loads consisting of motor-operated utilization equipment that is fastened in place and has a motor larger than 1/8 hp in combination with other loads, the total calculated load shall be based on 125 percent of the largest motor load plus the sum of the other loads.
For circuits supplying lighting units that have ballasts, transformers, autotransformers, or LED drivers, the calculated load shall be based on the total ampere ratings of such units and not on the total watts of the lamps.
It shall be permissible to apply demand factors for range loads in accordance with Table 220.55, including Note 4.
The calculated load of a feeder or service shall not be less than the sum of the loads on the branch circuits supplied, as determined by Part II of this article, after any applicable demand factors permitted by Part III or IV or required by Part V have been applied.
Informational Note: See Examples D1(a) through D10 in Informative Annex D. See 220.18(B) for the maximum load in amperes permitted for lighting units operating at less than 100 percent power factor.
The demand factors specified in Table 220.42 shall apply to that portion of the total branch-circuit load calculated for general illumination. They shall not be applied in determining the number of branch circuits for general illumination.
Table 220.42 Lighting Load Demand Factors
| Type of Occupancy | Portion of Lighting Load to Which Demand Factor Applies (Volt-Amperes) | Demand Factor (%) |
|---|---|---|
| Dwelling units | First 3000 or less at | 100 |
| From 3001 to 120,000 at | 35 | |
| Remainder over 120,000 at | 25 | |
| Hospitals* | First 50,000 or less at | 40 |
| Remainder over 50,000 at | 20 | |
| Hotels and motels, including apartment houses without provision for cooking by tenants* | First 20,000 or less at | 50 |
| From 20,001 to 100,000 at | 40 | |
| Remainder over 100,000 at | 30 | |
| Warehouses (storage) | First 12,500 or less at | 100 |
| Remainder over 12,500 at | 50 | |
| All others | Total volt-amperes | 100 |
*The demand factors of this table shall not apply to the calculated load of feeders or services supplying areas in hospitals, hotels, and motels where the entire lighting is likely to be used at one time, as in operating rooms, ballrooms, or dining rooms.
For show-window lighting, a load of not less than 660 volt-amperes/linear meter or 200 volt-amperes/linear foot shall be included for a show window, measured horizontally along its base.
For track lighting in other than dwelling units or guest rooms or guest suites of hotels or motels, an additional load of 150 volt-amperes shall be included for every 600 mm (2 ft) of lighting track or fraction thereof. Where multicircuit track is installed, the load shall be considered to be divided equally between the track circuits.
Receptacle loads calculated in accordance with 220.14(H) and (I) shall be permitted to be made subject to the demand factors given in Table 220.42 or Table 220.44.
Table 220.44 Demand Factors for Non-Dwelling Receptacle Loads
| Portion of Receptacle Load to Which Demand Factor Applies (Volt-Amperes) | Demand Factor (%) |
|---|---|
| First 10 kVA or less at | 100 |
| Remainder over 10 kVA at | 50 |
Fixed electric space-heating loads shall be calculated at 100 percent of the total connected load. However, in no case shall a feeder or service load current rating be less than the rating of the largest branch circuit supplied.
Exception: Where reduced loading of the conductors results from units operating on duty-cycle, intermittently, or from all units not operating at the same time, the authority having jurisdiction may grant permission for feeder and service conductors to have an ampacity less than 100 percent, provided the conductors have an ampacity for the load so determined.
In each dwelling unit, the load shall be calculated at 1500 volt-amperes for each 2-wire small-appliance branch circuit as covered by 210.11(C)(1). Where the load is subdivided through two or more feeders, the calculated load for each shall include not less than 1500 volt-amperes for each 2-wire smallappliance branch circuit. These loads shall be permitted to be included with the general lighting load and subjected to the demand factors provided in Table 220.42.
Exception: The individual branch circuit permitted by 210.52(B)(1), Exception No. 2, shall be permitted to be excluded from the calculation required by 220.52.
A load of not less than 1500 volt-amperes shall be included for each 2-wire laundry branch circuit installed as covered by 210.11(C)(2). This load shall be permitted to be included with the general lighting load and subjected to the demand factors provided in Table 220.42.
It shall be permissible to apply a demand factor of 75 percent to the nameplate rating load of four or more appliances fastened in place, other than electric ranges, clothes dryers, spaceheating equipment, or air-conditioning equipment, that are served by the same feeder or service in a one-family, two-family, or multifamily dwelling.
The load for household electric clothes dryers in a dwelling unit(s) shall be either 5000 watts (volt-amperes) or the nameplate rating, whichever is larger, for each dryer served. The use of the demand factors in Table 220.54 shall be permitted. Where two or more single-phase dryers are supplied by a 3-phase, 4-wire feeder or service, the total load shall be calculated on the basis of twice the maximum number connected between any two phases. Kilovolt-amperes (kVA) shall be considered equivalent to kilowatts (kW) for loads calculated in this section.
| Number of Dryers | Demand Factor (%) |
|---|---|
| 1-4 | 100 |
| 5 | 85 |
| 6 | 75 |
| 7 | 65 |
| 8 | 60 |
| 9 | 55 |
| 10 | 50 |
| 11 | 47 |
| 12-23 | 47% minus 1% for each dryer exceeding 11 |
| 24-42 | 35% minus 0.5% for each dryer exceeding 23 |
| 43 and over | 25% |
The load for household electric ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliances individually rated in excess of 13/4 kW shall be permitted to be calculated in accordance with Table 220.55. Kilovolt-amperes (kVA) shall be considered equivalent to kilowatts (kW) for loads calculated under this section.
Where two or more single-phase ranges are supplied by a 3-phase, 4-wire feeder or service, the total load shall be calculated on the basis of twice the maximum number connected between any two phases.
Informational Note No. 1: See the examples in Informative Annex D.
Table 220.55 Demand Factors and Loads for Household Electric Ranges, Wall-Mounted Ovens, Counter-Mounted Cooking Units, and Other Household Cooking Appliances over 13/4 kW Rating (Column C to be used in all cases except as otherwise permitted in Note 3.)
| Number of Appliances | Demand Factor (%) (See Notes) | Column C Maximum Demand (kW) (See Notes) (Not over 12 kW Rating) | |
|---|---|---|---|
| Column A (Less than 31/2 kW Rating) | Column B (31/2 kW through 83/4 kW Rating) | ||
| 1 | 80 | 80 | 8 |
| 2 | 75 | 65 | 11 |
| 3 | 70 | 55 | 14 |
| 4 | 66 | 50 | 17 |
| 5 | 62 | 45 | 20 |
| 6 | 59 | 43 | 21 |
| 7 | 56 | 40 | 22 |
| 8 | 53 | 36 | 23 |
| 9 | 51 | 35 | 24 |
| 10 | 49 | 34 | 25 |
| 11 | 47 | 32 | 26 |
| 12 | 45 | 32 | 27 |
| 13 | 43 | 32 | 28 |
| 14 | 41 | 32 | 29 |
| 15 | 40 | 32 | 30 |
| 16 | 39 | 28 | 31 |
| 17 | 38 | 28 | 32 |
| 18 | 37 | 28 | 33 |
| 19 | 36 | 28 | 34 |
| 20 | 35 | 28 | 35 |
| 21 | 34 | 26 | 36 |
| 22 | 33 | 26 | 37 |
| 23 | 32 | 26 | 38 |
| 24 | 31 | 26 | 39 |
| 25 | 30 | 26 | 40 |
| 26-30 | 30 | 24 | 15 kW + 1 kW for each range |
| 31-40 | 30 | 22 | |
| 41-50 | 30 | 20 | 25 kW + 3/4 kW for each range |
| 51-60 | 30 | 18 | |
| 61 and over | 30 | 16 | |
Notes:
- Over 12 kW through 27 kW ranges all of same rating. For ranges individually rated more than 12 kW but not more than 27 kW, the maximum demand in Column C shall be increased 5 percent for each additional kilowatt of rating or major fraction thereof by which the rating of individual ranges exceeds 12 kW.
- Over 83/4 kW through 27 kW ranges of unequal ratings. For ranges individually rated more than 83/4 kW and of different ratings, but none exceeding 27 kW, an average value of rating shall be calculated by adding together the ratings of all ranges to obtain the total connected load (using 12 kW for any range rated less than 12 kW) and dividing by the total number of ranges. Then the maximum demand in Column C shall be increased 5 percent for each kilowatt or major fraction thereof by which this average value exceeds 12 kW.
- Over 13/4 kW through 83/4 kW. In lieu of the method provided in Column C, it shall be permissible to add the nameplate ratings of all household cooking appliances rated more than 13/4 kW but not more than 83/4 kW and multiply the sum by the demand factors specified in Column A or Column B for the given number of appliances. Where the rating of cooking appliances falls under both Column A and Column B, the demand factors for each column shall be applied to the appliances for that column, and the results added together.
- Branch-Circuit Load. It shall be permissible to calculate the branch-circuit load for one range in accordance with Table 220.55. The branch-circuit load for one wall-mounted oven or one counter-mounted cooking unit shall be the nameplate rating of the appliance. The branch-circuit load for a counter-mounted cooking unit and not more than two wall-mounted ovens, all supplied from a single branch circuit and located in the same room, shall be calculated by adding the nameplate rating of the individual appliances and treating this total as equivalent to one range.
- This table shall also apply to household cooking appliances rated over 13/4 kW and used in instructional programs.
It shall be permissible to calculate the load for commercial electric cooking equipment, dishwasher booster heaters, water heaters, and other kitchen equipment in accordance with Table 220.56. These demand factors shall be applied to all equipment that has either thermostatic control or intermittent use as kitchen equipment. These demand factors shall not apply to space-heating, ventilating, or air-conditioning equipment.
However, in no case shall the feeder or service calculated load be less than the sum of the largest two kitchen equipment loads.
| Number of Units of Equipment | Demand Factor (%) |
|---|---|
| 1 | 100 |
| 2 | 100 |
| 3 | 90 |
| 4 | 80 |
| 5 | 70 |
| 6 and over | 65 |
The feeder or service neutral load shall be the maximum unbalance of the load determined by this article. The maximum unbalanced load shall be the maximum net calculated load between the neutral conductor and any one ungrounded conductor.
Exception: For 3-wire, 2-phase or 5-wire, 2-phase systems, the maximum unbalanced load shall be the maximum net calculated load between the neutral conductor and any one ungrounded conductor multiplied by 140 percent.
A service or feeder supplying the following loads shall be permitted to have an additional demand factor of 70 percent applied to the amount in 220.61(B)(1) or portion of the amount in 220.61(B)(2) determined by the basic calculation:
- A feeder or service supplying household electric ranges, wall-mounted ovens, counter-mounted cooking units, and electric dryers, where the maximum unbalanced load has been determined in accordance with Table 220.55 for ranges and Table 220.54 for dryers
- That portion of the unbalanced load in excess of 200 amperes where the feeder or service is supplied from a 3-wire dc or single-phase ac system; or a 4-wire, 3-phase, 3-wire, 2-phase system; or a 5-wire, 2-phase system
Informational Note: See Examples D1(a), D1(b), D2(b), D4(a), and D5(a) in Informative Annex D.
There shall be no reduction of the neutral or grounded conductor capacity applied to the amount in 220.61(C)(1), or portion of the amount in (C)(2), from that determined by the basic calculation:
- Any portion of a 3-wire circuit consisting of 2 ungrounded conductors and the neutral conductor of a 4-wire, 3-phase, wye-connected system
- That portion consisting of nonlinear loads supplied from a 4-wire, wye-connected, 3-phase system
Informational Note: A 3-phase, 4-wire, wye-connected power system used to supply power to nonlinear loads may necessitate that the power system design allow for the possibility of high harmonic neutral conductor currents.
This section applies to a dwelling unit having the total connected load served by a single 120/240-volt or 208Y/120-volt set of 3-wire service or feeder conductors with an ampacity of 100 or greater. It shall be permissible to calculate the feeder and service loads in accordance with this section instead of the method specified in Part III of this article. The calculated load shall be the result of adding the loads from 220.82(B) and (C). Feeder and service-entrance conductors whose calculated load is determined by this optional calculation shall be permitted to have the neutral load determined by 220.61.
The general calculated load shall be not less than 100 percent of the first 10 kVA plus 40 percent of the remainder of the following loads:
- 33 volt-amperes/m2 or 3 volt-amperes/ft2 for general lighting and general-use receptacles. The floor area for each floor shall be calculated from the outside dimensions of the dwelling unit. The calculated floor area shall not include open porches, garages, or unused or unfinished spaces not adaptable for future use.
- 1500 volt-amperes for each 2-wire, 20-ampere small-appliance branch circuit and each laundry branch circuit covered in 210.11(C)(1) and (C)(2).
- The nameplate rating of the following:
- All appliances that are fastened in place, permanently connected, or located to be on a specific circuit
- Ranges, wall-mounted ovens, counter-mounted cooking units
- Clothes dryers that are not connected to the laundry branch circuit specified in item (2)
- Water heaters
- The nameplate ampere or kVA rating of all permanently connected motors not included in item (3).
The largest of the following six selections (load in kVA) shall be included:
- 100 percent of the nameplate rating(s) of the air conditioning and cooling.
- 100 percent of the nameplate rating(s) of the heat pump when the heat pump is used without any supplemental electric heating.
- 100 percent of the nameplate rating(s) of the heat pump compressor and 65 percent of the supplemental electric heating for central electric space-heating systems. If the heat pump compressor is prevented from operating at the same time as the supplementary heat, it does not need to be added to the supplementary heat for the total central space heating load.
- 65 percent of the nameplate rating(s) of electric space heating if less than four separately controlled units.
- 40 percent of the nameplate rating(s) of electric space heating if four or more separately controlled units.
- 100 percent of the nameplate ratings of electric thermal storage and other heating systems where the usual load is expected to be continuous at the full nameplate value. Systems qualifying under this selection shall not be calculated under any other selection in 220.82(C).
This section shall be permitted to be used to determine if the existing service or feeder is of sufficient capacity to serve additional loads. Where the dwelling unit is served by a 120/240-volt or 208Y/120-volt, 3-wire service, it shall be permissible to calculate the total load in accordance with 220.83(A) or (B).
The following percentages shall be used for existing and additional new loads.
| Load (kVA) | Percent of Load |
|---|---|
| First 8 kVA of load at | 100 |
| Remainder of load at | 40 |
Load calculations shall include the following:
- General lighting and general-use receptacles at 33 volt-amperes/m2 or 3 volt-amperes/ft2 as determined by 220.12
- 1500 volt-amperes for each 2-wire, 20-ampere small-appliance branch circuit and each laundry branch circuit covered in 210.11(C)(1) and (C)(2)
- The nameplate rating of the following:
- All appliances that are fastened in place, permanently connected, or located to be on a specific circuit
- Ranges, wall-mounted ovens, counter-mounted cooking units
- Clothes dryers that are not connected to the laundry branch circuit specified in item (2)
- Water heaters
The following percentages shall be used for existing and additional new loads. The larger connected load of airconditioning or space-heating, but not both, shall be used.
| Load | Percent of Load |
|---|---|
| Air-conditioning equipment | 100 |
| Central electric space-heating | 100 |
| Less than four separately controlled space-heating units | 100 |
| First 8 kVA of all other loads | 100 |
| Remainder of all other loads | 40 |
Other loads shall include the following:
- General lighting and general-use receptacles at 33 volt-amperes/m2 or 3 volt-amperes/ft2 as determined by 220.12
- 1500 volt-amperes for each 2-wire, 20-ampere small-appliance branch circuit and each laundry branch circuit covered in 210.11(C)(1) and (C)(2)
- The nameplate rating of the following:
- All appliances that are fastened in place, permanently connected, or located to be on a specific circuit
- Ranges, wall-mounted ovens, counter-mounted cooking units
- Clothes dryers that are not connected to the laundry branch circuit specified in (2)
- Water heaters
| Number of Dwelling Units | Demand Factor (%) | ||
|---|---|---|---|
| 3-5 | 45 | ||
| 6-7 | 44 | ||
| 8-10 | 43 | ||
| 11 | 42 | ||
| 12-13 | 41 | ||
| 14-15 | 40 | ||
| 16-17 | 39 | ||
| 18-20 | 38 | ||
| 21 | 37 | ||
| 22-23 | 36 | ||
| 24-25 | 35 | ||
| 26-27 | 34 | ||
| 28-30 | 33 | ||
| 31 | 32 | ||
| 32-33 | 31 | ||
| 34-36 | 30 | ||
| 37-38 | 29 | ||
| 39-42 | 28 | ||
| 43-45 | 27 | ||
| 46-50 | 26 | ||
| 51-55 | 25 | ||
| 56-61 | 24 | ||
| 62 and over | 23 | ||
It shall be permissible to calculate the load of a feeder or service that supplies three or more dwelling units of a multifamily dwelling in accordance with Table 220.84 instead of Part III of this article if all the following conditions are met:
- No dwelling unit is supplied by more than one feeder.
- Each dwelling unit is equipped with electric cooking equipment. Exception: When the calculated load for multifamily dwellings without electric cooking in Part III of this article exceeds that calculated under Part IV for the identical load plus electric cooking (based on 8 kW per unit), the lesser of the two loads shall be permitted to be used.
- Each dwelling unit is equipped with either electric space heating or air conditioning, or both. Feeders and service conductors whose calculated load is determined by this optional calculation shall be permitted to have the neutral load determined by 220.61.
House loads shall be calculated in accordance with Part III of this article and shall be in addition to the dwelling unit loads calculated in accordance with Table 220.84.
The calculated load to which the demand factors of Table 220.84 apply shall include the following:
- 33 volt-amperes/m2 or 3 volt-amperes/ft2 for general lighting and general-use receptacles
- 1500 volt-amperes for each 2-wire, 20-ampere smallappliance branch circuit and each laundry branch circuit covered in 210.11(C)(1) and (C)(2)
- The nameplate rating of the following:
- All appliances that are fastened in place, permanently connected, or located to be on a specific circuit
- Ranges, wall-mounted ovens, counter-mounted cooking units
- Clothes dryers that are not connected to the laundry branch circuit specified in item (2)
- Water heaters
- The nameplate ampere or kVA rating of all permanently connected motors not included in item (3)
- The larger of the air-conditioning load or the fixed electric space-heating load
Where two dwelling units are supplied by a single feeder and the calculated load under Part III of this article exceeds that for three identical units calculated under 220.84, the lesser of the two loads shall be permitted to be used.
The calculation of a feeder or service load for schools shall be permitted in accordance with Table 220.86 in lieu of Part III of this article where equipped with electric space heating, air conditioning, or both. The connected load to which the demand factors of Table 220.86 apply shall include all of the interior and exterior lighting, power, water heating, cooking, other loads, and the larger of the air-conditioning load or space-heating load within the building or structure.
Feeders and service conductors whose calculated load is determined by this optional calculation shall be permitted to have the neutral load determined by 220.61. Where the building or structure load is calculated by this optional method, feeders within the building or structure shall have ampacity as permitted in Part III of this article; however, the ampacity of an individual feeder shall not be required to be larger than the ampacity for the entire building.
This section shall not apply to portable classroom buildings.
| Connected Load | Demand Factor (Percent) | |
|---|---|---|
| First 33 VA/m2 Plus, | (3 VA/ft2) at | 100 |
| Over 33 through 220 VA/m2 Plus, | (3 through 20 VA/ft2) at | 75 |
| Remainder over 220 VA/m2 | (20 VA/ft2) at | 25 |
The calculation of a feeder or service load for existing installations shall be permitted to use actual maximum demand to determine the existing load under all of the following conditions:
- The maximum demand data is available for a 1-year period. Exception: If the maximum demand data for a 1-year period is not available, the calculated load shall be permitted to be based on the maximum demand (measure of average power demand over a 15-minute period) continuously recorded over a minimum 30-day period using a recording ammeter or power meter connected to the highest loaded phase of the feeder or service, based on the initial loading at the start of the recording. The recording shall reflect the maximum demand of the feeder or service by being taken when the building or space is occupied and shall include by measurement or calculation the larger of the heating or cooling equipment load, and other loads that may be periodic in nature due to seasonal or similar conditions.
- The maximum demand at 125 percent plus the new load does not exceed the ampacity of the feeder or rating of the service.
- The feeder has overcurrent protection in accordance with 240.4, and the service has overload protection in accordance with 230.90.
Calculation of a service or feeder load, where the feeder serves the total load, for a new restaurant shall be permitted in accordance with Table 220.88 in lieu of Part III of this article.
Service or feeder conductors whose calculated load is determined by this optional calculation shall be permitted to have the neutral load determined by 220.61.
Table 220.88 Optional Method — Permitted Load Calculations for Service and Feeder Conductors for New Restaurants
| Total Connected Load (kVA) | All Electric Restaurant Calculated Loads (kVA) | Not All Electric Restaurant Calculated Loads (kVA) |
|---|---|---|
| 0-200 | 80% | 100% |
| 201-325 | 10% (amount over 200) + 160.0 | 50% (amount over 200) + 200.0 |
| 326-800 | 50% (amount over 325) + 172.5 | 45% (amount over 325) + 262.5 |
| Over 800 | 50% (amount over 800) + 410.0 | 20% (amount over 800) + 476.3 |
Note: Add all electrical loads, including both heating and cooling loads, to calculate the total connected load. Select the one demand factor that applies from the table, then multiply the total connected load by this single demand factor.
Farm loads shall be calculated in accordance with Part V.
The feeder or service load of a farm dwelling unit shall be calculated in accordance with the provisions for dwellings in Part III or IV of this article. Where the dwelling has electric heat and the farm has electric grain-drying systems, Part IV of this article shall not be used to calculate the dwelling load where the dwelling and farm loads are supplied by a common service.
Where a feeder or service supplies a farm building or other load having two or more separate branch circuits, the load for feeders, service conductors, and service equipment shall be calculated in accordance with demand factors not less than indicated in Table 220.102.
Table 220.102 Method for Calculating Farm Loads for Other Than Dwelling Unit
| Ampere Load at 240 Volts Maximum | Demand Factor (%) |
|---|---|
| The greater of the following: | |
| All loads that are expected to operate simultaneously, or | 100 |
| 125 percent of the full load current of the largest motor, or | |
| First 60 amperes of the load | |
| Next 60 amperes of all other loads | 50 |
| Remainder of other loads | 25 |
Where supplied by a common service, the total load of the farm for service conductors and service equipment shall be calculated in accordance with the farm dwelling unit load and demand factors specified in Table 220.103. Where there is equipment in two or more farm equipment buildings or for loads having the same function, such loads shall be calculated in accordance with Table 220.102 and shall be permitted to be combined as a single load in Table 220.103 for calculating the total load.
Table 220.103 Method for Calculating Total Farm Load
| Individual Loads Calculated in Accordance with Table 220.102 | Demand Factor (%) |
|---|---|
| Largest load | 100 |
| Second largest load | 75 |
| Third largest load | 65 |
| Remaining loads | 50 |
Note: To this total load, add the load of the farm dwelling unit calculated in accordance with Part III or IV of this article. Where the dwelling has electric heat and the farm has electric grain-drying systems, Part IV of this article shall not be used to calculate the dwelling load.
Upcodes Diagrams
This article covers requirements for outside branch circuits and feeders run on or between buildings, structures, or poles on the premises; and electrical equipment and wiring for the supply of utilization equipment that is located on or attached to the outside of buildings, structures, or poles.
Informational Note: For additional information on wiring over 1000 volts, see ANSI C2-2007, National Electrical Safety Code.
Application of other articles, including additional requirements to specific cases of equipment and conductors, is shown in Table 225.3.
Table 225.3 Other Articles
| Equipment/Conductors | Article |
|---|---|
| Branch circuits | 210 |
| Class 1, Class 2, and Class 3 remote-control, signaling, and power-limited circuits | 725 |
| Communications circuits | 800 |
| Community antenna television and radio distribution systems | 820 |
| Conductors for general wiring | 310 |
| Electrically driven or controlled irrigation machines | 675 |
| Electric signs and outline lighting | 600 |
| Feeders | 215 |
| Fire alarm systems | 760 |
| Fixed outdoor electric deicing and snow-melting equipment | 426 |
| Floating buildings | 553 |
| Grounding and bonding | 250 |
| Hazardous (classified) locations | 500 |
| Hazardous (classified) locations — specific | 510 |
| Marinas and boatyards | 555 |
| Messenger-supported wiring | 396 |
| Mobile homes, manufactured homes, and mobile home parks | 550 |
| Open wiring on insulators | 398 |
| Over 1000 volts, general | 490 |
| Overcurrent protection | 240 |
| Radio and television equipment | 810 |
| Services | 230 |
| Solar photovoltaic systems | 690 |
| Swimming pools, fountains, and similar installations | 680 |
| Use and identification of grounded conductors | 200 |
Where within 3.0 m (10 ft) of any building or structure other than supporting poles or towers, open individual (aerial) overhead conductors shall be insulated for the nominal voltage. Conductors in cables or raceways, except Type MI cable, shall be of the rubber-covered type or thermoplastic type and, in wet locations, shall comply with 310.10(C). Conductors for festoon lighting shall be of the rubber-covered or thermoplastic type.
Exception: Equipment grounding conductors and grounded circuit conductors shall be permitted to be bare or covered as specifically permitted elsewhere in this Code.
The ampacity of outdoor branch-circuit and feeder conductors shall be in accordance with 310.15 based on loads as determined under 220.10 and Part III of Article 220.
Open individual conductors shall not be smaller than the following:
- For 1000 volts, nominal, or less, 10 AWG copper or 8 AWG aluminum for spans up to 15 m (50 ft) in length, and 8 AWG copper or 6 AWG aluminum for a longer span unless supported by a messenger wire
- For over 1000 volts, nominal, 6 AWG copper or 4 AWG aluminum where open individual conductors, and 8 AWG copper or 6 AWG aluminum where in cable
Overhead conductors for festoon lighting shall not be smaller than 12 AWG unless the conductors are supported by messenger wires. In all spans exceeding 12 m (40 ft), the conductors shall be supported by messenger wire. The messenger wire shall be supported by strain insulators. Conductors or messenger wires shall not be attached to any fire escape, downspout, or plumbing equipment.
For the supply of lighting equipment installed outdoors, the branch circuits shall comply with Article 210 and 225.7(B) through (D).
The ampacity of the neutral conductor shall not be less than the maximum net calculated load current between the neutral conductor and all ungrounded conductors connected to any one phase of the circuit.
Circuits exceeding 120 volts, nominal, between conductors and not exceeding 277 volts, nominal, to ground shall be permitted to supply luminaires for illumination of outdoor areas of industrial establishments, office buildings, schools, stores, and other commercial or public buildings.
The load on outdoor branch circuits shall be as determined by 220.10.
The load on outdoor feeders shall be as determined by Part III of Article 220.
The installation of outside wiring on surfaces of buildings (or other structures) shall be permitted for circuits of not over 1000 volts, nominal, as open wiring on insulators, as multiconductor cable, as Type MC cable, as Type UF cable, as Type MI cable, as messenger-supported wiring, in rigid metal conduit (RMC), in intermediate metal conduit (IMC), in rigid polyvinyl chloride (PVC) conduit, in reinforced thermosetting resin conduit (RTRC), in cable trays, as cablebus, in wireways, in auxiliary gutters, in electrical metallic tubing (EMT), in flexible metal conduit (FMC), in liquidtight flexible metal conduit (LFMC), in liquidtight flexible nonmetallic conduit (LFNC), and in busways. Circuits of over 1000 volts, nominal, shall be installed as provided in 300.37.
Feeder and branch-circuit conductors entering or exiting buildings or structures shall be in installed in accordance with the requirements of 230.52. Overhead branch circuits and feeders attached to buildings or structures shall be installed in accordance with the requirements of 230.54.
Open conductors shall be supported on glass or porcelain knobs, racks, brackets, or strain insulators.
Conductors of 1000 volts, nominal, or less, shall comply with the spacings provided in Table 230.51(C).
Open conductors shall be separated from open conductors of other circuits or systems by not less than 100 mm (4 in.).
Conductors on poles shall have a separation of not less than 300 mm (1 ft) where not placed on racks or brackets. Conductors supported on poles shall provide a horizontal climbing space not less than the following:
- Power conductors below communications conductors — 750 mm (30 in.)
- Power conductors alone or above communications conductors:
- 300 volts or less — 600 mm (24 in.)
- Over 300 volts — 750 mm (30 in.)
- Communications conductors below power conductors — same as power conductors
- Communications conductors alone — no requirement
Supports over a building shall be in accordance with 230.29.
The point of attachment to a building shall be in accordance with 230.26.
The means of attachment to a building shall be in accordance with 230.27.
Only feeder or branch-circuit conductors specified within this section shall be permitted to be attached to the feeder and/or branch-circuit mast. Masts used for the support of final spans of feeders or branch circuits shall be installed in accordance with 225.17(A) and (B).
The mast shall be of adequate strength or be supported by braces or guys to withstand safely the strain imposed by the overhead feeder or branch-circuit conductors. Hubs intended for use with a conduit that serves as a mast for support of feeder or branch-circuit conductors shall be identified for use with a mast.
Feeder and/or branch-circuit conductors shall not be attached to a mast between a weatherhead or the end of the conduit and a coupling where the coupling is located above the last point of securement to the building or other structure or is located above the building or other structure.
Overhead spans of open conductors and open multiconductor cables of not over 1000 volts, nominal, shall have a clearance of not less than the following:
- 3.0 m (10 ft) — above finished grade, sidewalks, or from any platform or projection from which they might be reached where the voltage does not exceed 150 volts to ground and accessible to pedestrians only
- 3.7 m (12 ft) — over residential property and driveways, and those commercial areas not subject to truck traffic where the voltage does not exceed 300 volts to ground
- 4.5 m (15 ft) — for those areas listed in the 3.7-m (12-ft) classification where the voltage exceeds 300 volts to ground
- 5.5 m (18 ft) — over public streets, alleys, roads, parking areas subject to truck traffic, driveways on other than residential property, and other land traversed by vehicles, such as cultivated, grazing, forest, and orchard
- 7.5 m (24.5 ft) — over track rails of railroads
Overhead spans of open conductors and open multiconductor cables shall have a vertical clearance of not less than 2.5 m (8 ft) above the roof surface. The vertical clearance above the roof level shall be maintained for a distance not less than 900 mm (3 ft) in all directions from the edge of the roof.
Exception No. 1: The area above a roof surface subject to pedestrian or vehicular traffic shall have a vertical clearance from the roof surface in accordance with the clearance requirements of 225.18.
Exception No. 2: Where the voltage between conductors does not exceed 300, and the roof has a slope of 100 mm in 300 mm (4 in. in 12 in.) or greater, a reduction in clearance to 900 mm (3 ft) shall be permitted.
Exception No. 3: Where the voltage between conductors does not exceed 300, a reduction in clearance above only the overhanging portion of the roof to not less than 450 mm (18 in.) shall be permitted if (1) not more than 1.8 m (6 ft) of the conductors, 1.2 m (4 ft) horizontally, pass above the roof overhang and (2) they are terminated at a through-the-roof raceway or approved support.
Exception No. 4: The requirement for maintaining the vertical clearance 900 mm (3 ft) from the edge of the roof shall not apply to the final conductor span where the conductors are attached to the side of a building.
From signs, chimneys, radio and television antennas, tanks, and other nonbuilding or nonbridge structures, clearances — vertical, diagonal, and horizontal — shall not be less than 900 mm (3 ft).
Clearances shall not be less than 900 mm (3 ft).
Final spans to the building they supply, or from which they are fed, shall be permitted to be attached to the building, but they shall be kept not less than 900 mm (3 ft) from windows that are designed to be opened, and from doors, porches, balconies, ladders, stairs, fire escapes, or similar locations.
Exception: Conductors run above the top level of a window shall be permitted to be less than the 900-mm (3-ft) requirement.
The vertical clearance of final spans above, or within 900 mm (3 ft) measured horizontally of, platforms, projections, or surfaces from which they might be reached shall be maintained in accordance with 225.18.
The overhead branch-circuit and feeder conductors shall not be installed beneath openings through which materials may be moved, such as openings in farm and commercial buildings, and shall not be installed where they obstruct entrance to these buildings' openings.
Where buildings exceed three stories or 15 m (50 ft) in height, overhead lines shall be arranged, where practicable, so that a clear space (or zone) at least 1.8 m (6 ft) wide will be left either adjacent to the buildings or beginning not over 2.5 m (8 ft) from them to facilitate the raising of ladders when necessary for fire fighting.
Raceways on exteriors of buildings or other structures shall be arranged to drain and shall be suitable for use in wet locations.
Locations of lamps for outdoor lighting shall be below all energized conductors, transformers, or other electric utilization equipment, unless either of the following apply:
- Clearances or other safeguards are provided for relamping operations.
- Equipment is controlled by a disconnecting means that is lockable in accordance with 110.25.
Vegetation such as trees shall not be used for support of overhead conductor spans.
Where a raceway enters a building or structure from an underground distribution system, it shall be sealed in accordance with 300.5(G). Spare or unused raceways shall also be sealed. Sealants shall be identified for use with the cable insulation, conductor insulation. bare conductor, shield, or other components.
A building or other structure that is served by a branch circuit or feeder on the load side of a service disconnecting means shall be supplied by only one feeder or branch circuit unless permitted in 225.30(A) through (E). For the purpose of this section, a multiwire branch circuit shall be considered a single circuit.
Where a branch circuit or feeder originates in these additional buildings or other structures, only one feeder or branch circuit shall be permitted to supply power back to the original building or structure, unless permitted in 225.30(A) through (E).
Additional feeders or branch circuits shall be permitted to supply the following:
- Fire pumps
- Emergency systems
- Legally required standby systems
- Optional standby systems
- Parallel power production systems
- Systems designed for connection to multiple sources of supply for the purpose of enhanced reliability
By special permission, additional feeders or branch circuits shall be permitted for either of the following:
- Multiple-occupancy buildings where there is no space available for supply equipment accessible to all occupants
- A single building or other structure sufficiently large to make two or more supplies necessary
Additional feeders or branch circuits shall be permitted where the capacity requirements are in excess of 2000 amperes at a supply voltage of 1000 volts or less.
Additional feeders or branch circuits shall be permitted for different voltages, frequencies, or phases or for different uses, such as control of outside lighting from multiple locations.
Additional feeders or branch circuits shall be permitted to supply installations under single management where documented safe switching procedures are established and maintained for disconnection.
Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure.
The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors. For the purposes of this section, the requirements in 230.6 shall be utilized.
Exception No. 1: For installations under single management, where documented safe switching procedures are established and maintained for disconnection, and where the installation is monitored by qualified individuals, the disconnecting means shall be permitted to be located elsewhere on the premises.
Exception No. 2: For buildings or other structures qualifying under the provisions of Article 685, the disconnecting means shall be permitted to be located elsewhere on the premises.
Exception No. 3: For towers or poles used as lighting standards, the disconnecting means shall be permitted to be located elsewhere on the premises.
Exception No. 4: For poles or similar structures used only for support of signs installed in accordance with Article 600, the disconnecting means shall be permitted to be located elsewhere on the premises.
The disconnecting means for each supply permitted by 225.30 shall consist of not more than six switches or six circuit breakers mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard or switchgear. There shall be no more than six disconnects per supply grouped in any one location.
Exception: For the purposes of this section, disconnecting means used solely for the control circuit of the ground-fault protection system, or the control circuit of the power-operated supply disconnecting means, installed as part of the listed equipment, shall not be considered a supply disconnecting means.
Two or three single-pole switches or breakers capable of individual operation shall be permitted on multiwire circuits, one pole for each ungrounded conductor, as one multipole disconnect, provided they are equipped with identified handle ties or a master handle to disconnect all ungrounded conductors with no more than six operations of the hand.
The two to six disconnects as permitted in 225.33 shall be grouped. Each disconnect shall be marked to indicate the load served.
Exception: One of the two to six disconnecting means permitted in 225.33, where used only for a water pump also intended to provide fire protection, shall be permitted to be located remote from the other disconnecting means.
The one or more additional disconnecting means for fire pumps or for emergency, legally required standby or optional standby system permitted by 225.30 shall be installed sufficiently remote from the one to six disconnecting means for normal supply to minimize the possibility of simultaneous interruption of supply.
In a multiple-occupancy building, each occupant shall have access to the occupant's supply disconnecting means.
Exception: In a multiple-occupancy building where electric supply and electrical maintenance are provided by the building management and where these are under continuous building management supervision, the supply disconnecting means supplying more than one occupancy shall be permitted to be accessible to authorized management personnel only.
The disconnecting means specified in 225.31 shall be comprised of a circuit breaker, molded case switch, general-use switch, snap switch, or other approved means. Where applied in accordance with 250.32(B), Exception No. 1, the disconnecting means shall be suitable for use as service equipment.
Where a building or structure has any combination of feeders, branch circuits, or services passing through it or supplying it, a permanent plaque or directory shall be installed at each feeder and branch-circuit disconnect location denoting all other services, feeders, or branch circuits supplying that building or structure or passing through that building or structure and the area served by each.
Exception No. 1: A plaque or directory shall not be required for large-capacity multibuilding industrial installations under single management, where it is ensured that disconnection can be accomplished by establishing and maintaining safe switching procedures.
Exception No. 2: This identification shall not be required for branch circuits installed from a dwelling unit to a second building or structure.
Disconnecting means shall meet the requirements of 225.38(A) through (D).
The disconnecting means shall consist of either (1) a manually operable switch or a circuit breaker equipped with a handle or other suitable operating means or (2) a power-operable switch or circuit breaker, provided the switch or circuit breaker can be opened by hand in the event of a power failure.
Each building or structure disconnecting means shall simultaneously disconnect all ungrounded supply conductors that it controls from the building or structure wiring system.
Where the building or structure disconnecting means does not disconnect the grounded conductor from the grounded conductors in the building or structure wiring, other means shall be provided for this purpose at the location of the disconnecting means. A terminal or bus to which all grounded conductors can be attached by means of pressure connectors shall be permitted for this purpose.
In a multisection switchboard or switchgear, disconnects for the grounded conductor shall be permitted to be in any section of the switchboard or switchgear, provided that any such switchboard section or switchgear section is marked.
The building or structure disconnecting means shall plainly indicate whether it is in the open or closed position.
The feeder or branch-circuit disconnecting means shall have a rating of not less than the calculated load to be supplied, determined in accordance with Parts I and II of Article 220 for branch circuits, Part III or IV of Article 220 for feeders, or Part V of Article 220 for farm loads. Where the branch circuit or feeder disconnecting means consists of more than one switch or circuit breaker, as permitted by 225.33, combining the ratings of all the switches or circuit breakers for determining the rating of the disconnecting means shall be permitted. In no case shall the rating be lower than specified in 225.39(A), (B), (C), or (D).
For installations to supply only limited loads of a single branch circuit, the branch circuit disconnecting means shall have a rating of not less than 15 amperes.
For installations consisting of not more than two 2-wire branch circuits, the feeder or branch-circuit disconnecting means shall have a rating of not less than 30 amperes.
For a one-family dwelling, the feeder disconnecting means shall have a rating of not less than 100 amperes, 3-wire.
For all other installations, the feeder or branch-circuit disconnecting means shall have a rating of not less than 60 amperes.
Where a feeder overcurrent device is not readily accessible, branch-circuit overcurrent devices shall be installed on the load side, shall be mounted in a readily accessible location, and shall be of a lower ampere rating than the feeder overcurrent device.
The sizing of conductors over 1000 volts shall be in accordance with 210.19(B) for branch circuits and 215.2(B) for feeders.
Where oil switches or air, oil, vacuum, or sulfur hexafluoride circuit breakers constitute a building disconnecting means, an isolating switch with visible break contacts and meeting the requirements of 230.204(B), (C), and (D) shall be installed on the supply side of the disconnecting means and all associated equipment.
Exception: The isolating switch shall not be required where the disconnecting means is mounted on removable truck panels or switchgear units that cannot be opened unless the circuit is disconnected and that, when removed from the normal operating position, automatically disconnect the circuit breaker or switch from all energized parts.
A building or structure disconnecting means shall be located in accordance with 225.32, or, if not readily accessible, it shall be operable by mechanical linkage from a readily accessible point. For multibuilding industrial installations under single management, it shall be permitted to be electrically operated by a readily accessible, remote-control device in a separate building or structure.
Each building or structure disconnect shall simultaneously disconnect all ungrounded supply conductors it controls and shall have a fault-closing rating not less than the maximum available short-circuit current available at its supply terminals.
Exception: Where the individual disconnecting means consists of fused cutouts, the simultaneous disconnection of all ungrounded supply conductors shall not be required if there is a means to disconnect the load before opening the cutouts. A permanent legible sign shall be installed adjacent to the fused cutouts and shall read DISCONNECT LOAD BEFORE OPENING CUTOUTS.
Where fused switches or separately mounted fuses are installed, the fuse characteristics shall be permitted to contribute to the fault closing rating of the disconnecting means.
Disconnecting means shall be lockable in accordance with 110.25.
Exception: Where an individual disconnecting means consists of fused cutouts, a suitable enclosure capable of being locked and sized to contain all cutout fuse holders shall be installed at a convenient location to the fused cutouts
Disconnecting means shall clearly indicate whether they are in the open "off" or closed "on" position.
Where disconnecting means handles are operated vertically, the "up" position of the handle shall be the "on" position.
Exception: A switching device having more than one "on " position, such as a double throw switch, shall not be required to comply with this requirement.
Where a building or structure has any combination of feeders, branch circuits, or services passing through or supplying it, a permanent plaque or directory shall be installed at each feeder and branch-circuit disconnect location that denotes all other services, feeders, or branch circuits supplying that building or structure or passing through that building or structure and the area served by each.
The complete electrical system design, including settings for protective, switching, and control circuits, shall be prepared in advance and made available on request to the authority having jurisdiction and shall be performance tested when first installed on-site. Each protective, switching, and control circuit shall be adjusted in accordance with the system design and tested by actual operation using current injection or equivalent methods as necessary to ensure that each and every such circuit operates correctly to the satisfaction of the authority having jurisdiction.
All instrument transformers shall be tested to verify correct polarity and burden.
Each protective relay shall be demonstrated to operate by injecting current or voltage, or both, at the associated instrument transformer output terminal and observing that the associated switching and signaling functions occur correctly and in proper time and sequence to accomplish the protective function intended.
Each switching circuit shall be observed to operate the associated equipment being switched.
All metering circuits shall be verified to operate correctly from voltage and current sources in a similar manner to protective relay circuits.
Complete acceptance tests shall be performed, after the substation installation is completed, on all assemblies, equipment, conductors, and control and protective systems, as applicable, to verify the integrity of all the systems.
All relays and metering that use phase differences for operation shall be verified by measuring phase angles at the relay under actual load conditions after operation commences.
A test report covering the results of the tests required in 225.56(A) shall be delivered to the authority having jurisdiction prior to energization.
Informational Note: For an example of acceptance specifications, see NETA ATS-2007, Acceptance Testing Specifications for Electrical Power Distribution Equipment and Systems, published by the InterNational Electrical Testing Association.
| Location | Clearance | |
|---|---|---|
| m | ft | |
| Open land subject to vehicles, cultivation, or grazing | 5.6 | 18.5 |
| Roadways, driveways, parking lots, and alleys | 5.6 | 18.5 |
| Walkways | 4.1 | 13.5 |
| Rails | 8.1 | 26.5 |
| Spaces and ways for pedestrians and restricted traffic | 4.4 | 14.5 |
| Water areas not suitable for boating | 5.2 | 17.0 |
The clearances over roadways, walkways, rail, water, and open land for conductors and live parts up to 22 kV, nominal, to ground or less shall be not less than the values shown in Table 225.60.
Clearances for the categories shown in Table 225.60 shall be increased by 10 mm (0.4 in.) per kV above 22,000 volts.
For special cases, such as where crossings will be made over lakes, rivers, or areas using large vehicles such as mining operations, specific designs shall be engineered considering the special circumstances and shall be approved by the authority having jurisdiction.
Informational Note: For additional information, see ANSI C2-2007, National Electrical Safety Code.
Table 225.61 Clearances over Buildings and Other Structures
| Clearance from Conductors or Live Parts from: | Horizontal | Vertical | ||
|---|---|---|---|---|
| m | ft | m | ft | |
| Building walls, projections, and windows | 2.3 | 7.5 | — | — |
| Balconies, catwalks, and similar areas accessible to people | 2.3 | 7.5 | 4.1 | 13.5 |
| Over or under roofs or projections not readily accessible to people | — | — | 3.8 | 12.5 |
| Over roofs accessible to vehicles but not trucks | — | — | 4.1 | 13.5 |
| Over roofs accessible to trucks | — | — | 5.6 | 18.5 |
| Other structures | 2.3 | 7.5 | — | — |
The clearances over buildings and other structures for conductors and live parts up to 22 kV, nominal, to ground or less shall be not less than the values shown in Table 225.61.
Clearances for the categories shown in Table 225.61 shall be increased by 10 mm (0.4 in.) per kV above 22,000 volts.
Informational Note: For additional information, see ANSI C2-2007, National Electrical Safety Code.
This article covers service conductors and equipment for control and protection of services and their installation requirements.
Informational Note: See Figure 230.1.
| General | Part I |
| Overhead Service Conductors | Part II |
| Underground Service Conductors | Part III |
| Service-Entrance Conductors | Part IV |
| Service Equipment—General | Part V |
| Service Equipment—Disconnecting Means | Part VI |
| Service Equipment—Overcurrent Protection | Part VII |
| Services Exceeding 1000 Volts, Nominal | Part VIII |
Figure 230.1 Services.
A building or other structure served shall be supplied by only one service unless permitted in 230.2(A) through (D). For the purpose of 230.40, Exception No. 2 only, underground sets of conductors, 1/0 AWG and larger, running to the same location and connected together at their supply end but not connected together at their load end shall be considered to be supplying one service.
Additional services shall be permitted to supply the following:
- Fire pumps
- Emergency systems
- Legally required standby systems
- Optional standby systems
- Parallel power production systems
- Systems designed for connection to multiple sources of supply for the purpose of enhanced reliability
By special permission, additional services shall be permitted for either of the following:
- Multiple-occupancy buildings where there is no available space for service equipment accessible to all occupants
- A single building or other structure sufficiently large to make two or more services necessary
Additional services shall be permitted under any of the following:
- Where the capacity requirements are in excess of 2000 amperes at a supply voltage of 1000 volts or less
- Where the load requirements of a single-phase installation are greater than the serving agency normally supplies through one service
- By special permission
Where a building or structure is supplied by more than one service, or any combination of branch circuits, feeders, and services, a permanent plaque or directory shall be installed at each service disconnect location denoting all other services, feeders, and branch circuits supplying that building or structure and the area served by each. See 225.37.
Service conductors supplying a building or other structure shall not pass through the interior of another building or other structure.
Conductors shall be considered outside of a building or other structure under any of the following conditions:
- Where installed under not less than 50 mm (2 in.) of concrete beneath a building or other structure
- Where installed within a building or other structure in a raceway that is encased in concrete or brick not less than 50 mm (2 in.) thick
- Where installed in any vault that meets the construction requirements of Article 450, Part III
- Where installed in conduit and under not less than 450 mm (18 in.) of earth beneath a building or other structure
- Where installed within rigid metal conduit (Type RMC) or intermediate metal conduit (Type IMC) used to accommodate the clearance requirements in 230.24 and routed directly through an eave but not a wall of a building.
Conductors other than service conductors shall not be installed in the same service raceway or service cable.
Exception No. 1: Grounding electrode conductors and equipment bonding jumpers or conductors.
Exception No. 2: Load management control conductors having overcurrent protection.
Service conductors and final spans shall comply with 230.9(A), (B), and (C).
Service conductors installed as open conductors or multiconductor cable without an overall outer jacket shall have a clearance of not less than 900 mm (3 ft) from windows that are designed to be opened, doors, porches, balconies, ladders, stairs, fire escapes, or similar locations.
Exception: Conductors run above the top level of a window shall be permitted to be less than the 900-mm (3-ft) requirement.
The vertical clearance of final spans above, or within 900 mm (3 ft) measured horizontally of, platforms, projections, or surfaces from which they might be reached shall be maintained in accordance with 230.24(B).
Overhead service conductors shall not be installed beneath openings through which materials may be moved, such as openings in farm and commercial buildings, and shall not be installed where they obstruct entrance to these building openings.
Vegetation such as trees shall not be used for support of overhead service conductors.
Individual conductors shall be insulated or covered.
Exception: The grounded conductor of a multiconductor cable shall be permitted to be bare.
Conductors shall have sufficient ampacity to carry the current for the load as calculated in accordance with Article 220 and shall have adequate mechanical strength.
The conductors shall not be smaller than 8 AWG copper or 6 AWG aluminum or copper-clad aluminum.
Exception: Conductors supplying only limited loads of a single branch circuit — such as small polyphase power, controlled water heaters, and similar loads — shall not be smaller than 12 AWG hard-drawn copper or equivalent.
The grounded conductor shall not be less than the minimum size as required by 250.24(C).
Overhead service conductors shall not be readily accessible and shall comply with 230.24(A) through (E) for services not over 1000 volts, nominal.
Conductors shall have a vertical clearance of not less than 2.5 m (8 ft) above the roof surface. The vertical clearance above the roof level shall be maintained for a distance of not less than 900 mm (3 ft) in all directions from the edge of the roof.
Exception No. 1: The area above a roof surface subject to pedestrian or vehicular traffic shall have a vertical clearance from the roof surface in accordance with the clearance requirements of 230.24(B).
Exception No. 2: Where the voltage between conductors does not exceed 300 and the roof has a slope of 100 mm in 300 mm (4 in. in 12 in.) or greater, a reduction in clearance to 900 mm (3 ft) shall be permitted.
Exception No. 3: Where the voltage between conductors does not exceed 300, a reduction in clearance above only the overhanging portion of the roof to not less than 450 mm (18 in.) shall be permitted if (1) not more than 1.8 m (6 ft) of overhead service conductors, 1.2 m (4 ft) horizontally, pass above the roof overhang, and (2) they are terminated at a through-the-roof raceway or approved support.
Informational Note: See 230.28 for mast supports.
Exception No. 4: The requirement for maintaining the vertical clearance 900 mm (3 ft) from the edge of the roof shall not apply to the final conductor span where the service drop or overhead service conductors are attached to the side of a building.
Overhead service conductors, where not in excess of 600 volts, nominal, shall have the following minimum clearance from final grade:
- 3.0 m (10 ft) — at the electrical service entrance to buildings, also at the lowest point of the drip loop of the building electrical entrance, and above areas or sidewalks accessible only to pedestrians, measured from final grade or other accessible surface only for overhead service conductors supported on and cabled together with a grounded bare messenger where the voltage does not exceed 150 volts to ground
- 3.7 m (12 ft) — over residential property and driveways, and those commercial areas not subject to truck traffic where the voltage does not exceed 300 volts to ground
- 4.5 m (15 ft) — for those areas listed in the 3.7-m (12-ft) classification where the voltage exceeds 300 volts to ground
- 5.5 m (18 ft) — over public streets, alleys, roads, parking areas subject to truck traffic, driveways on other than residential property, and other land such as cultivated, grazing, forest, and orchard
The point of attachment of the overhead service conductors to a building or other structure shall provide the minimum clearances as specified in 230.9 and 230.24. In no case shall this point of attachment be less than 3.0 m (10 ft) above finished grade.
Multiconductor cables used for overhead service conductors shall be attached to buildings or other structures by fittings identified for use with service conductors. Open conductors shall be attached to fittings identified for use with service conductors or to noncombustible, nonabsorbent insulators securely attached to the building or other structure.
Only power service-drop or overhead service conductors shall be permitted to be attached to a service mast. Service masts used for the support of service-drop or overhead service conductors shall be installed in accordance with 230.28(A) and (B).
The service mast shall be of adequate strength or be supported by braces or guys to withstand safely the strain imposed by the service-drop or overhead service conductors. Hubs intended for use with a conduit that serves as a service mast shall be identified for use with service-entrance equipment.
Service-drop or overhead service conductors shall not be attached to a service mast between a weatherhead or the end of the conduit and a coupling, where the coupling is located above the last point of securement to the building or other structure or is located above the building or other structure.
Service conductors passing over a roof shall be securely supported by substantial structures. Where practicable, such supports shall be independent of the building.
Underground service conductors shall be insulated for the applied voltage.
Exception: A grounded conductor shall be permitted to be uninsulated as follows:
- Bare copper used in a raceway
- Bare copper for direct burial where bare copper is judged to be suitable for the soil conditions
- Bare copper for direct burial without regard to soil conditions where part of a cable assembly identified for underground use
- Aluminum or copper-clad aluminum without individual insulation or covering where part of a cable assembly identified for underground use in a raceway or for direct burial
Underground service conductors shall be installed in accordance with the applicable requirements of this Code covering the type of wiring method used and shall be limited to the following methods:
- Type RMC conduit
- Type IMC conduit
- Type NUCC conduit
- Type HDPE conduit
- Type PVC conduit
- Type RTRC conduit
- Type IGS cable
- Type USE conductors or cables
- Type MV or Type MC cable identified for direct burial applications
- Type MI cable, where suitably protected against physical damage and corrosive conditions
Underground service conductors shall have sufficient ampacity to carry the current for the load as calculated in accordance with Article 220 and shall have adequate mechanical strength.
The conductors shall not be smaller than 8 AWG copper or 6 AWG aluminum or copper-clad aluminum.
Exception: Conductors supplying only limited loads of a single branch circuit — such as small polyphase power, controlled water heaters, and similar loads — shall not be smaller than 12 AWG copper or 10 AWG aluminum or copper-clad aluminum.
The grounded conductor shall not be less than the minimum size required by 250.24(C).
Underground service conductors shall be protected against damage in accordance with 300.5. Service conductors entering a building or other structure shall be installed in accordance with 230.6 or protected by a raceway wiring method identified in 230.43.
Service conductors shall be permitted to be spliced or tapped in accordance with 110.14, 300.5(E), 300.13, and 300.15.
Each service drop, set of overhead service conductors, set of underground service conductors, or service lateral shall supply only one set of service-entrance conductors.
Exception No. 1: A building with more than one occupancy shall be permitted to have one set of service entrance conductors for each service, as defined in 230.2, run to each occupancy or group of occupancies. If the number of service disconnect locations for any given classification of service does not exceed six, the requirements of 230.2(E) shall apply at each location. If the number of service disconnect locations exceeds six for any given supply classification, all service disconnect locations for all supply characteristics, together with any branch circuit or feeder supply sources, if applicable, shall be clearly described using suitable graphics or text, or both, on one or more plaques located in an approved, readily accessible location(s) on the building or structure served and as near as practicable to the point(s) of attachment or entry(ies) for each service drop or service lateral, and for each set of overhead or underground service conductors.
Exception No. 2: Where two to six service disconnecting means in separate enclosures are grouped at one location and supply separate loads from one service drop, set of overhead service conductors, set of underground service conductors, or service lateral, one set of service-entrance conductors shall be permitted to supply each or several such service equipment enclosures.
Exception No. 3: A single-family dwelling unit and its accessory structures shall be permitted to have one set of service-entrance conductors run to each from a single service drop, set of overhead service conductors, set of underground service conductors, or service lateral.
Exception No. 4: Two-family dwellings, multifamily dwellings, and multiple occupancy buildings shall be permitted to have one set of service-entrance conductors installed to supply the circuits covered in 210.25.
Exception No. 5: One set of service-entrance conductors connected to the supply side of the normal service disconnecting means shall be permitted to supply each or several systems covered by 230.82(5) or 230.82(6).
Service-entrance conductors entering or on the exterior of buildings or other structures shall be insulated.
Exception: A grounded conductor shall be permitted to be uninsulated as follows:
- Bare copper used in a raceway or part of a service cable assembly
- Bare copper for direct burial where bare copper is judged to be suitable for the soil conditions
- Bare copper for direct burial without regard to soil conditions where part of a cable assembly identified for underground use
- Aluminum or copper-clad aluminum without individual insulation or covering where part of a cable assembly or identified for underground use in a raceway, or for direct burial
- Bare conductors used in an auxiliary gutter
The ampacity of service-entrance conductors shall not be less than either 230.42(A)(1), (A)(2), or (A)(3). Loads shall be determined in accordance with Part III, IV, or V of Article 220, as applicable. Ampacity shall be determined from 310.15. The maximum allowable current of busways shall be that value for which the busway has been listed or labeled.
- The sum of the noncontinuous loads plus 125 percent of continuous loads Exception: Grounded conductors that are not connected to an overcurrent device shall be permitted to be sized at 100 percent of the continuous and noncontinuous load.
- The sum of the noncontinuous load plus the continuous load after the application of any adjustment or correction factors.
- The sum of the noncontinuous load plus the continuous load if the service-entrance conductors terminate in an overcurrent device where both the overcurrent device and its assembly are listed for operation at 100 percent of their rating
In addition to the requirements of 230.42(A), the minimum ampacity for ungrounded conductors for specific installations shall not be less than the rating of the service disconnecting means specified in 230.79(A) through (D).
The grounded conductor shall not be smaller than the minimum size as required by 250.24(C).
Service-entrance conductors shall be installed in accordance with the applicable requirements of this Code covering the type of wiring method used and shall be limited to the following methods:
- Open wiring on insulators
- Type IGS cable
- Rigid metal conduit (RMC)
- Intermediate metal conduit (IMC)
- Electrical metallic tubing (EMT)
- Electrical nonmetallic tubing
- Service-entrance cables
- Wireways
- Busways
- Auxiliary gutters
- Rigid polyvinyl chloride conduit (PVC)
- Cablebus
- Type MC cable
- Mineral-insulated, metal-sheathed cable, Type MI
- Flexible metal conduit (FMC) not over 1.8 m (6 ft) long or liquidtight flexible metal conduit (LFMC) not over 1.8 m (6 ft) long between a raceway, or between a raceway and service equipment, with a supply-side bonding jumper routed with the flexible metal conduit (FMC) or the liquidtight flexible metal conduit (LFMC) according to the provisions of 250.102(A), (B), (C), and (E)
- Liquidtight flexible nonmetallic conduit (LFNC)
- High density polyethylene conduit (HDPE)
- Nonmetallic underground conduit with conductors (NUCC)
- Reinforced thermosetting resin conduit (RTRC)
Cable tray systems shall be permitted to support service-entrance conductors. Cable trays used to support service-entrance conductors shall contain only service-entrance conductors and shall be limited to the following methods:
- Type SE cable
- Type MC cable
- Type MI cable
- Type IGS cable
- Single conductors 1/0 and larger with CT rating
Such cable trays shall be identified with permanently affixed labels with the wording "Service-Entrance Conductors." The labels shall be located so as to be visible after installation with a spacing not to exceed 3 m (10 ft) so that the service-entrance conductors are able to be readily traced through the entire length of the cable tray.
Exception: Conductors, other than service-entrance conductors, shall be permitted to be installed in a cable tray with service-entrance conductors, provided a solid fixed barrier of a material compatible with the cable tray is installed to separate the service-entrance conductors from other conductors installed in the cable tray.
All other service-entrance conductors, other than underground service entrance conductors, shall be protected against physical damage as specified in 230.50(B)(1) or (B)(2).
Service-entrance cables, where subject to physical damage, shall be protected by any of the following:
- Rigid metal conduit (RMC)
- Intermediate metal conduit (IMC)
- Schedule 80 PVC conduit
- Electrical metallic tubing (EMT)
- Reinforced thermosetting resin conduit (RTRC)
- Other approved means
Individual open conductors and cables, other than service-entrance cables, shall not be installed within 3.0 m (10 ft) of grade level or where exposed to physical damage.
Service-entrance cables or individual open service-entrance conductors shall be supported as specified in 230.51(A), (B), or (C).
Service-entrance cables shall be supported by straps or other approved means within 300 mm (12 in.) of every service head, gooseneck, or connection to a raceway or enclosure and at intervals not exceeding 750 mm (30 in.).
Individual open conductors shall be installed in accordance with Table 230.51(C). Where exposed to the weather, the conductors shall be mounted on insulators or on insulating supports attached to racks, brackets, or other approved means. Where not exposed to the weather, the conductors shall be mounted on glass or porcelain knobs.
Table 230.51(C) Supports
| Maximum Volts | Maximum Distance Between Supports | Minimum Clearance | ||||
|---|---|---|---|---|---|---|
| Between Conductors | From Surface | |||||
| m | ft | mm | in. | mm | in. | |
| 1000 | 2.7 | 9 | 150 | 6 | 50 | 2 |
| 1000 | 4.5 | 15 | 300 | 12 | 50 | 2 |
| 300 | 1.4 | 41/2 | 75 | 3 | 50 | 2 |
| 1000* | 1.4* | 41/2* | 65* | 21/2* | 25* | 1* |
*Where not exposed to weather.
Where individual open conductors enter a building or other structure, they shall enter through roof bushings or through the wall in an upward slant through individual, noncombustible, nonabsorbent insulating tubes. Drip loops shall be formed on the conductors before they enter the tubes.
Where exposed to the weather, raceways enclosing service-entrance conductors shall be suitable for use in wet locations and arranged to drain. Where embedded in masonry, raceways shall be arranged to drain.
Service raceways shall be equipped with a service head at the point of connection to service-drop or overhead service conductors. The service head shall be listed for use in wet locations.
Service-entrance cables shall be equipped with a service head. The service head shall be listed for use in wet locations.
Exception: Type SE cable shall be permitted to be formed in a gooseneck and taped with a self-sealing weather-resistant thermoplastic.
Service heads and goosenecks in service-entrance cables shall be located above the point of attachment of the service-drop or overhead service conductors to the building or other structure.
Service-entrance cables shall be held securely in place.
Service heads shall have conductors of different potential brought out through separately bushed openings.
Exception: For jacketed multiconductor service-entrance cable without splice.
Drip loops shall be formed on individual conductors. To prevent the entrance of moisture, service-entrance conductors shall be connected to the service-drop or overhead service conductors either (1) below the level of the service head or (2) below the level of the termination of the service-entrance cable sheath.
Service-entrance and overhead service conductors shall be arranged so that water will not enter service raceway or equipment.
On a 4-wire, delta-connected service where the midpoint of one phase winding is grounded, the service conductor having the higher phase voltage to ground shall be durably and permanently marked by an outer finish that is orange in color, or by other effective means, at each termination or junction point.
Energized parts shall be enclosed so that they will not be exposed to accidental contact or shall be guarded as in 230.62(B).
Energized parts that are not enclosed shall be installed on a switchboard, panelboard, or control board and guarded in accordance with 110.18 and 110.27. Where energized parts are guarded as provided in 110.27(A)(1) and (A)(2), a means for locking or sealing doors providing access to energized parts shall be provided.
Service equipment rated at 1000 volts or less shall be marked to identify it as being suitable for use as service equipment. All service equipment shall be listed. Individual meter socket enclosures shall not be considered service equipment.
Means shall be provided to disconnect all conductors in a building or other structure from the service-entrance conductors.
The service disconnecting means shall be installed in accordance with 230.70(A)(1), (A)(2), and (A)(3).
The service disconnecting means shall be installed at a readily accessible location either outside of a building or structure or inside nearest the point of entrance of the service conductors.
Where a remote control device(s) is used to actuate the service disconnecting means, the service disconnecting means shall be located in accordance with 230.70(A)(1).
Each service disconnecting means shall be suitable for the prevailing conditions. Service equipment installed in hazardous (classified) locations shall comply with the requirements of Articles 500 through 517.
The service disconnecting means for each service permitted by 230.2, or for each set of service-entrance conductors permitted by 230.40, Exception No. 1, 3, 4, or 5, shall consist of not more than six switches or sets of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard or in switchgear. There shall be not more than six sets of disconnects per service grouped in any one location.
For the purpose of this section, disconnecting means installed as part of listed equipment and used solely for the following shall not be considered a service disconnecting means:
- Power monitoring equipment
- Surge-protective device(s)
- Control circuit of the ground-fault protection system
- Power-operable service disconnecting means
Two or three single-pole switches or breakers, capable of individual operation, shall be permitted on multiwire circuits, one pole for each ungrounded conductor, as one multipole disconnect, provided they are equipped with identified handle ties or a master handle to disconnect all conductors of the service with no more than six operations of the hand.
Informational Note: See 408.36, Exception No. 1 and Exception No. 3, for service equipment in certain panelboards, and see 430.95 for service equipment in motor control centers.
The two to six disconnects as permitted in 230.71 shall be grouped. Each disconnect shall be marked to indicate the load served.
Exception: One of the two to six service disconnecting means permitted in 230.71, where used only for a water pump also intended to provide fire protection, shall be permitted to be located remote from the other disconnecting means. If remotely installed in accordance with this exception, a plaque shall be posted at the location of the remaining grouped disconnects denoting its location.
The one or more additional service disconnecting means for fire pumps, emergency systems, legally required standby, or optional standby services permitted by 230.2 shall be installed remote from the one to six service disconnecting means for normal service to minimize the possibility of simultaneous interruption of supply.
In a multiple-occupancy building, each occupant shall have access to the occupant's service disconnecting means.
Exception: In a multiple-occupancy building where electric service and electrical maintenance are provided by the building management and where these are under continuous building management supervision, the service disconnecting means supplying more than one occupancy shall be permitted to be accessible to authorized management personnel only.
Each service disconnect shall simultaneously disconnect all ungrounded service conductors that it controls from the premises wiring system.
Where the service disconnecting means does not disconnect the grounded conductor from the premises wiring, other means shall be provided for this purpose in the service equipment. A terminal or bus to which all grounded conductors can be attached by means of pressure connectors shall be permitted for this purpose. In a multisection switchboard or switchgear, disconnects for the grounded conductor shall be permitted to be in any section of the switchboard or switchgear, provided that any such switchboard or switchgear section is marked.
The service disconnecting means for ungrounded service conductors shall consist of one of the following:
- A manually operable switch or circuit breaker equipped with a handle or other suitable operating means
- A power-operated switch or circuit breaker, provided the switch or circuit breaker can be opened by hand in the event of a power supply failure
The service disconnecting means shall plainly indicate whether it is in the open (off) or closed (on) position.
The service disconnecting means shall have a rating not less than the calculated load to be carried, determined in accordance with Part III, IV, or V of Article 220, as applicable. In no case shall the rating be lower than specified in 230.79(A), (B), (C), or (D).
For installations to supply only limited loads of a single branch circuit, the service disconnecting means shall have a rating of not less than 15 amperes.
For installations consisting of not more than two 2-wire branch circuits, the service disconnecting means shall have a rating of not less than 30 amperes.
For a one-family dwelling, the service disconnecting means shall have a rating of not less than 100 amperes, 3-wire.
For all other installations, the service disconnecting means shall have a rating of not less than 60 amperes.
Where the service disconnecting means consists of more than one switch or circuit breaker, as permitted by 230.71, the combined ratings of all the switches or circuit breakers used shall not be less than the rating required by 230.79.
The service conductors shall be connected to the service disconnecting means by pressure connectors, clamps, or other approved means. Connections that depend on solder shall not be used.
Only the following equipment shall be permitted to be connected to the supply side of the service disconnecting means:
- Cable limiters or other current-limiting devices.
- Meters and meter sockets nominally rated not in excess of 1000 volts, provided that all metal housings and service enclosures are grounded in accordance with Part VII and bonded in accordance with Part V of Article 250.
- Meter disconnect switches nominally rated not in excess of 1000 V that have a short-circuit current rating equal to or greater than the available short-circuit current, provided that all metal housings and service enclosures are grounded in accordance with Part VII and bonded in accordance with Part V of Article 250. A meter disconnect switch shall be capable of interrupting the load served. A meter disconnect shall be legibly field marked on its exterior in a manner suitable for the environment as follows: METER DISCONNECT
NOT SERVICE EQUIPMENT - Instrument transformers (current and voltage), impedance shunts, load management devices, surge arresters, and Type 1 surge-protective devices.
- Taps used only to supply load management devices, circuits for standby power systems, fire pump equipment, and fire and sprinkler alarms, if provided with service equipment and installed in accordance with requirements for service-entrance conductors.
- Solar photovoltaic systems, fuel cell systems, or interconnected electric power production sources.
- Control circuits for power-operable service disconnecting means, if suitable overcurrent protection and disconnecting means are provided.
- Ground-fault protection systems or Type 2 surge-protective devices, where installed as part of listed equipment, if suitable overcurrent protection and disconnecting means are provided.
- Connections used only to supply listed communications equipment under the exclusive control of the serving electric utility, if suitable overcurrent protection and disconnecting means are provided. For installations of equipment by the serving electric utility, a disconnecting means is not required if the supply is installed as part of a meter socket, such that access can only be gained with the meter removed.
Such protection shall be provided by an overcurrent device in series with each ungrounded service conductor that has a rating or setting not higher than the allowable ampacity of the conductor. A set of fuses shall be considered all the fuses required to protect all the ungrounded conductors of a circuit. Single-pole circuit breakers, grouped in accordance with 230.71(B), shall be considered as one protective device.
Exception No. 1: For motor-starting currents, ratings that comply with 430.52, 430.62, and 430.63 shall be permitted
Exception No. 2: Fuses and circuit breakers with a rating or setting that complies with 240.4(B) or (C) and 240.6 shall be permitted.
Exception No. 3: Two to six circuit breakers or sets of fuses shall be permitted as the overcurrent device to provide the overload protection. The sum of the ratings of the circuit breakers or fuses shall be permitted to exceed the ampacity of the service conductors, provided the calculated load does not exceed the ampacity of the service conductors.
Exception No. 4: Overload protection for fire pump supply conductors shall comply with 695.4(B)(2)(a).
Exception No. 5: Overload protection for 120/240-volt, 3-wire, single-phase dwelling services shall be permitted in accordance with the requirements of 310.15(B)(7).
No overcurrent device shall be inserted in a grounded service conductor except a circuit breaker that simultaneously opens all conductors of the circuit.
The service overcurrent device shall be an integral part of the service disconnecting means or shall be located immediately adjacent thereto.
Where the service overcurrent devices are locked or sealed or are not readily accessible to the occupant, branch-circuit or feeder overcurrent devices shall be installed on the load side, shall be mounted in a readily accessible location, and shall be of lower ampere rating than the service overcurrent device.
Where necessary to prevent tampering, an automatic overcurrent device that protects service conductors supplying only a specific load, such as a water heater, shall be permitted to be locked or sealed where located so as to be accessible.
The overcurrent device shall protect all circuits and devices.
Exception No. 1: The service switch shall be permitted on the supply side.
Exception No. 2: High-impedance shunt circuits, surge arresters, Type 1 surge-protective devices, surge-protective capacitors, and instrument transformers (current and voltage) shall be permitted to be connected and installed on the supply side of the service disconnecting means as permitted by 230.82.
Exception No. 3: Circuits for load management devices shall be permitted to be connected on the supply side of the service overcurrent device where separately provided with overcurrent protection.
Exception No. 4: Circuits used only for the operation of fire alarm, other protective signaling systems, or the supply to fire pump equipment shall be permitted to be connected on the supply side of the service overcurrent device where separately provided with overcurrent protection.
Exception No. 5: Meters nominally rated not in excess of 600 volts shall be permitted, provided all metal housings and service enclosures are grounded.
Exception No. 6: Where service equipment is power operable, the control circuit shall be permitted to be connected ahead of the service equipment if suitable overcurrent protection and disconnecting means are provided.
Ground-fault protection of equipment shall be provided for solidly grounded wye electric services of more than 150 volts to ground but not exceeding 1000 volts phase-to-phase for each service disconnect rated 1000 amperes or more. The grounded conductor for the solidly grounded wye system shall be connected directly to ground through a grounding electrode system, as specified in 250.50, without inserting any resistor or impedance device.
The rating of the service disconnect shall be considered to be the rating of the largest fuse that can be installed or the highest continuous current trip setting for which the actual overcurrent device installed in a circuit breaker is rated or can be adjusted.
Exception: The ground-fault protection provisions of this section shall not apply to a service disconnect for a continuous industrial process where a nonorderly shutdown will introduce additional or increased hazards.
The ground-fault protection system shall operate to cause the service disconnect to open all ungrounded conductors of the faulted circuit. The maximum setting of the ground-fault protection shall be 1200 amperes, and the maximum time delay shall be one second for ground-fault currents equal to or greater than 3000 amperes.
If a switch and fuse combination is used, the fuses employed shall be capable of interrupting any current higher than the interrupting capacity of the switch during a time that the ground-fault protective system will not cause the switch to open.
The ground-fault protection system shall be performance tested when first installed on site. The test shall be conducted in accordance with instructions that shall be provided with the equipment. A written record of this test shall be made and shall be available to the authority having jurisdiction.
Informational Note No. 1: Ground-fault protection that functions to open the service disconnect affords no protection from faults on the line side of the protective element. It serves only to limit damage to conductors and equipment on the load side in the event of an arcing ground fault on the load side of the protective element.
Informational Note No. 2: This added protective equipment at the service equipment may make it necessary to review the overall wiring system for proper selective overcurrent protection coordination. Additional installations of ground-fault protective equipment may be needed on feeders and branch circuits where maximum continuity of electric service is necessary.
Informational Note No. 3: Where ground-fault protection is provided for the service disconnect and interconnection is made with another supply system by a transfer device, means or devices may be needed to ensure proper ground-fault sensing by the ground-fault protection equipment.
Informational Note No. 4: See 517.17(A) for information on where an additional step of ground-fault protection is required for hospitals and other buildings with critical areas or life support equipment.
Service conductors and equipment used on circuits exceeding 1000 volts, nominal, shall comply with all the applicable provisions of the preceding sections of this article and with the following sections that supplement or modify the preceding sections. In no case shall the provisions of Part VIII apply to equipment on the supply side of the service point.
Informational Note: For clearances of conductors of over 1000 volts, nominal, see ANSI C2-2007, National Electrical Safety Code.
Service-entrance conductors to buildings or enclosures shall be installed to conform to 230.202(A) and (B).
Where oil switches or air, oil, vacuum, or sulfur hexafluoride circuit breakers constitute the service disconnecting means, an isolating switch with visible break contacts shall be installed on the supply side of the disconnecting means and all associated service equipment.
Exception: An isolating switch shall not be required where the circuit breaker or switch is mounted on removable truck panels or switchgear units where both of the following conditions apply:
- Cannot be opened unless the circuit is disconnected
- Where all energized parts are automatically disconnected when the circuit breaker or switch is removed from the normal operating position
Where fuses are of the type that can be operated as a disconnecting switch, a set of such fuses shall be permitted as the isolating switch.
The isolating switch shall be accessible to qualified persons only.
Isolating switches shall be provided with a means for readily connecting the load side conductors to a grounding electrode system, equipment ground busbar, or grounded steel structure when disconnected from the source of supply.
A means for grounding the load side conductors to a grounding electrode system, equipment grounding busbar, or grounded structural steel shall not be required for any duplicate isolating switch installed and maintained by the electric supply company.
The service disconnecting means shall be located in accordance with 230.70.
For either overhead or underground primary distribution systems on private property, the service disconnect shall be permitted to be located in a location that is not readily accessible, if the disconnecting means can be operated by mechanical linkage from a readily accessible point, or electronically in accordance with 230.205(C), where applicable.
Each service disconnect shall simultaneously disconnect all ungrounded service conductors that it controls and shall have a fault-closing rating that is not less than the maximum short-circuit current available at its supply terminals.
Where fused switches or separately mounted fuses are installed, the fuse characteristics shall be permitted to contribute to the fault-closing rating of the disconnecting means.
For multibuilding, industrial installations under single management, the service disconnecting means shall be permitted to be located at a separate building or structure. In such cases, the service disconnecting means shall be permitted to be electrically operated by a readily accessible, remote-control device.
Where the circuit breaker or alternative for it, as specified in 230.208 for service overcurrent devices, meets the requirements specified in 230.205, they shall constitute the service disconnecting means.
A short-circuit protective device shall be provided on the load side of, or as an integral part of, the service disconnect, and shall protect all ungrounded conductors that it supplies. The protective device shall be capable of detecting and interrupting all values of current, in excess of its trip setting or melting point, that can occur at its location. A fuse rated in continuous amperes not to exceed three times the ampacity of the conductor, or a circuit breaker with a trip setting of not more than six times the ampacity of the conductors, shall be considered as providing the required short-circuit protection.
Informational Note: See Table 310.60(C)(67) through Table 310.60(C)(86) for ampacities of conductors rated 2001 volts and above.
Equipment used to protect service-entrance conductors shall meet the requirements of Article 490, Part II.
The restriction to 80 percent of the rating for an enclosed overcurrent device for continuous loads shall not apply to overcurrent devices installed in systems operating at over 1000 volts.
Surge arresters installed in accordance with the requirements of Article 280 shall be permitted on each ungrounded overhead service conductor.
Service equipment, including instrument transformers, shall conform to Article 490, Part I.
Switchgear shall consist of a substantial metal structure and a sheet metal enclosure. Where installed over a combustible floor, suitable protection thereto shall be provided.
Where the voltage exceeds 35,000 volts between conductors that enter a building, they shall terminate in a switchgear compartment or a vault conforming to the requirements of 450.41 through 450.48.
Parts I through VII of this article provide the general requirements for overcurrent protection and overcurrent protective devices not more than 1000 volts, nominal. Part VIII covers overcurrent protection for those portions of supervised industrial installations operating at voltages of not more than 1000 volts, nominal. Part IX covers overcurrent protection over 1000 volts, nominal.
Informational Note: Overcurrent protection for conductors and equipment is provided to open the circuit if the current reaches a value that will cause an excessive or dangerous temperature in conductors or conductor insulation. See also 110.9 for requirements for interrupting ratings and 110.10 for requirements for protection against fault currents.
Current-Limiting Overcurrent Protective Device. A device that, when interrupting currents in its current-limiting range, reduces the current flowing in the faulted circuit to a magnitude substantially less than that obtainable in the same circuit if the device were replaced with a solid conductor having comparable impedance.
Supervised Industrial Installation. For the purposes of Part VIII, the industrial portions of a facility where all of the following conditions are met:
- Conditions of maintenance and engineering supervision ensure that only qualified persons monitor and service the system.
- The premises wiring system has 2500 kVA or greater of load used in industrial process(es), manufacturing activities, or both, as calculated in accordance with Article 220.
- The premises has at least one service or feeder that is more than 150 volts to ground and more than 300 volts phase-to-phase.
This definition excludes installations in buildings used by the industrial facility for offices, warehouses, garages, machine shops, and recreational facilities that are not an integral part of the industrial plant, substation, or control center.
Tap Conductors. As used in this article, a tap conductor is defined as a conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4.
Equipment shall be protected against overcurrent in accordance with the article in this Code that covers the type of equipment specified in Table 240.3.
Table 240.3 Other Articles
| Equipment | Article |
|---|---|
| Air-conditioning and refrigerating equipment | 440 |
| Appliances | 422 |
| Assembly occupancies | 518 |
| Audio signal processing, amplification, and reproduction equipment | 640 |
| Branch circuits | 210 |
| Busways | 368 |
| Capacitors | 460 |
| Class 1, Class 2, and Class 3 remote-control, signaling, and power-limited circuits | 725 |
| Cranes and hoists | 610 |
| Electric signs and outline lighting | 600 |
| Electric welders | 630 |
| Electrolytic cells | 668 |
| Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chairlifts | 620 |
| Emergency systems | 700 |
| Fire alarm systems | 760 |
| Fire pumps | 695 |
| Fixed electric heating equipment for pipelines and vessels | 427 |
| Fixed electric space-heating equipment | 424 |
| Fixed outdoor electric deicing and snow-melting equipment | 426 |
| Generators | 445 |
| Health care facilities | 517 |
| Induction and dielectric heating equipment | 665 |
| Industrial machinery | 670 |
| Luminaires, lampholders, and lamps | 410 |
| Motion picture and television studios and similar locations | 530 |
| Motors, motor circuits, and controllers | 430 |
| Phase converters | 455 |
| Pipe organs | 650 |
| Receptacles | 406 |
| Services | 230 |
| Solar photovoltaic systems | 690 |
| Switchboards and panelboards | 408 |
| Theaters, audience areas of motion picture and television studios, and similar locations | 520 |
| Transformers and transformer vaults | 450 |
| X-ray equipment | 660 |
Conductors, other than flexible cords, flexible cables, and fixture wires, shall be protected against overcurrent in accordance with their ampacities specified in 310.15, unless otherwise permitted or required in 240.4(A) through (G).
Informational Note: See ICEA P-32-382-2007 for information on allowable short-circuit currents for insulated copper and aluminum conductors.
Conductor overload protection shall not be required where the interruption of the circuit would create a hazard, such as in a material-handling magnet circuit or fire pump circuit. Short-circuit protection shall be provided.
Informational Note: See NFPA 20-2013, Standard for the Installation of Stationary Pumps for Fire Protection.
The next higher standard overcurrent device rating (above the ampacity of the conductors being protected) shall be permitted to be used, provided all of the following conditions are met:
- The conductors being protected are not part of a branch circuit supplying more than one receptacle for cord-and-plug-connected portable loads.
- The ampacity of the conductors does not correspond with the standard ampere rating of a fuse or a circuit breaker without overload trip adjustments above its rating (but that shall be permitted to have other trip or rating adjustments).
- The next higher standard rating selected does not exceed 800 amperes.
Where the overcurrent device is rated over 800 amperes, the ampacity of the conductors it protects shall be equal to or greater than the rating of the overcurrent device defined in 240.6.
Unless specifically permitted in 240.4(E) or (G), the overcurrent protection shall not exceed that required by (D)(1) through (D)(7) after any correction factors for ambient temperature and number of conductors have been applied.
7 amperes, provided all the following conditions are met:
- Continuous loads do not exceed 5.6 amperes.
- Overcurrent protection is provided by one of the following:
- Branch-circuit-rated circuit breakers listed and marked for use with 18 AWG copper wire
- Branch-circuit-rated fuses listed and marked for use with 18 AWG copper wire
- Class CC, Class J, or Class T fuses
10 amperes, provided all the following conditions are met:
- Continuous loads do not exceed 8 amperes.
- Overcurrent protection is provided by one of the following:
- Branch-circuit-rated circuit breakers listed and marked for use with 16 AWG copper wire
- Branch-circuit-rated fuses listed and marked for use with 16 AWG copper wire
- Class CC, Class J, or Class T fuses
15 amperes
20 amperes
30 amperes
Tap conductors shall be permitted to be protected against overcurrent in accordance with the following:
- 210.19(A)(3) and (A)(4), Household Ranges and Cooking Appliances and Other Loads
- 240.5(B)(2), Fixture Wire
- 240.21, Location in Circuit
- 368.17(B), Reduction in Ampacity Size of Busway
- 368.17(C), Feeder or Branch Circuits (busway taps)
- 430.53(D), Single Motor Taps
Single-phase (other than 2-wire) and multiphase (other than delta-delta, 3-wire) transformer secondary conductors shall not be considered to be protected by the primary overcurrent protective device. Conductors supplied by the secondary side of a single-phase transformer having a 2-wire (single-voltage) secondary, or a three-phase, delta-delta connected transformer having a 3-wire (single-voltage) secondary, shall be permitted to be protected by overcurrent protection provided on the primary (supply) side of the transformer, provided this protection is in accordance with 450.3 and does not exceed the value determined by multiplying the secondary conductor ampacity by the secondary-to-primary transformer voltage ratio.
Overcurrent protection for the specific conductors shall be permitted to be provided as referenced in Table 240.4(G).
Table 240.4(G) Specific Conductor Applications
| Conductor | Article | Section |
|---|---|---|
| Air-conditioning and refrigeration equipment circuit conductors | 440, Parts III, VI | |
| Capacitor circuit conductors | 460 | 460.8(B) and 460.25(A)—(D) |
| Control and instrumentation circuit conductors (Type ITC) | 727 | 727.9 |
| Electric welder circuit conductors | 630 | 630.12 and 630.32 |
| Fire alarm system circuit conductors | 760 | 760.43, 760.45, 760.121, and Chapter 9, Tables 12(A) and 12(B) |
| Motor-operated appliance circuit conductors | 422, Part II | |
| Motor and motor-control circuit conductors | 430, Parts II, III, IV, V, VI, VII | |
| Phase converter supply conductors | 455 | 455.7 |
| Remote-control, signaling, and power-limited circuit conductors | 725 | 725.43, 725.45, 725.121, and Chapter 9, Tables 11(A) and 11(B) |
| Secondary tie conductors | 450 | 450.6 |
Flexible cord and flexible cable, including tinsel cord and extension cords, and fixture wires shall be protected against overcurrent by either 240.5(A) or (B).
Flexible cord and flexible cable shall be protected by an overcurrent device in accordance with their ampacity as specified in Table 400.5(A)(1) and Table 400.5(A)(2). Fixture wire shall be protected against overcurrent in accordance with its ampacity as specified in Table 402.5. Supplementary overcurrent protection, as covered in 240.10, shall be permitted to be an acceptable means for providing this protection.
Flexible cord shall be protected, where supplied by a branch circuit, in accordance with one of the methods described in 240.5(B)(1), (B)(3), or (B)(4). Fixture wire shall be protected, where supplied by a branch circuit, in accordance with 240.5(B)(2).
Fixture wire shall be permitted to be tapped to the branch-circuit conductor of a branch circuit in accordance with the following:
- 20-ampere circuits — 18 AWG, up to 15 m (50 ft) of run length
- 20-ampere circuits — 16 AWG, up to 30 m (100 ft) of run length
- 20-ampere circuits — 14 AWG and larger
- 30-ampere circuits — 14 AWG and larger
- 40-ampere circuits — 12 AWG and larger
- 50-ampere circuits — 12 AWG and larger
Flexible cord used in listed extension cord sets shall be considered to be protected when applied within the extension cord listing requirements.
Flexible cord used in extension cords made with separately listed and installed components shall be permitted to be supplied by a branch circuit in accordance with the following:
20-ampere circuits — 16 AWG and larger
The standard ampere ratings for fuses and inverse time circuit breakers shall be considered 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, 600, 700, 800, 1000, 1200, 1600, 2000, 2500, 3000, 4000, 5000, and 6000 amperes. Additional standard ampere ratings for fuses shall be 1, 3, 6, 10, and 601. The use of fuses and inverse time circuit breakers with nonstandard ampere ratings shall be permitted.
The rating of adjustable-trip circuit breakers having external means for adjusting the current setting (long-time pickup setting), not meeting the requirements of 240.6(C), shall be the maximum setting possible.
A circuit breaker(s) that has restricted access to the adjusting means shall be permitted to have an ampere rating(s) that is equal to the adjusted current setting (long-time pickup setting). Restricted access shall be defined as located behind one of the following:
- Removable and sealable covers over the adjusting means
- Bolted equipment enclosure doors
- Locked doors accessible only to qualified personnel
Fuses and circuit breakers shall be permitted to be connected in parallel where they are factory assembled in parallel and listed as a unit. Individual fuses, circuit breakers, or combinations thereof shall not otherwise be connected in parallel.
Thermal relays and other devices not designed to open short circuits or ground faults shall not be used for the protection of conductors against overcurrent due to short circuits or ground faults, but the use of such devices shall be permitted to protect motor branch-circuit conductors from overload if protected in accordance with 430.40.
Where supplementary overcurrent protection is used for luminaires, appliances, and other equipment or for internal circuits and components of equipment, it shall not be used as a substitute for required branch-circuit overcurrent devices or in place of the required branch-circuit protection. Supplementary overcurrent devices shall not be required to be readily accessible.
Where an orderly shutdown is required to minimize the hazard(s) to personnel and equipment, a system of coordination based on the following two conditions shall be permitted:
Informational Note: The monitoring system may cause the condition to go to alarm, allowing corrective action or an orderly shutdown, thereby minimizing personnel hazard and equipment damage.
Ground-fault protection of equipment shall be provided in accordance with the provisions of 230.95 for solidly grounded wye electrical systems of more than 150 volts to ground but not exceeding 1000 volts phase-to-phase for each individual device used as a building or structure main disconnecting means rated 1000 amperes or more.
The provisions of this section shall not apply to the disconnecting means for the following:
- Continuous industrial processes where a nonorderly shutdown will introduce additional or increased hazards
- Installations where ground-fault protection is provided by other requirements for services or feeders
- Fire pumps
A fuse or an overcurrent trip unit of a circuit breaker shall be connected in series with each ungrounded conductor. A combination of a current transformer and overcurrent relay shall be considered equivalent to an overcurrent trip unit.
Informational Note: For motor circuits, see Parts III, IV, V, and XI of Article 430.
Circuit breakers shall open all ungrounded conductors of the circuit both manually and automatically unless otherwise permitted in 240.15(B)(1), (B)(2), (B)(3), and (B)(4).
Individual single-pole circuit breakers, with identified handle ties, shall be permitted as the protection for each ungrounded conductor of multiwire branch circuits that serve only single-phase line-to-neutral loads.
In grounded systems, individual single-pole circuit breakers rated 120/240 volts ac, with identified handle ties, shall be permitted as the protection for each ungrounded conductor for line-to-line connected loads for single-phase circuits.
For line-to-line loads in 4-wire, 3-phase systems or 5-wire, 2-phase systems, individual single-pole circuit breakers rated 120/240 volts ac with identified handle ties shall be permitted as the protection for each ungrounded conductor, if the systems have a grounded neutral point and the voltage to ground does not exceed 120 volts.
Individual single-pole circuit breakers rated 125/250 volts dc with identified handle ties shall be permitted as the protection for each ungrounded conductor for line-to-line connected loads for 3-wire, direct-current circuits supplied from a system with a grounded neutral where the voltage to ground does not exceed 125 volts.
Overcurrent protection shall be provided in each ungrounded circuit conductor and shall be located at the point where the conductors receive their supply except as specified in 240.21(A) through (H). Conductors supplied under the provisions of 240.21(A) through (H) shall not supply another conductor except through an overcurrent protective device meeting the requirements of 240.4.
Branch-circuit tap conductors meeting the requirements specified in 210.19 shall be permitted to have overcurrent protection as specified in 210.20.
Conductors shall be permitted to be tapped, without overcurrent protection at the tap, to a feeder as specified in 240.21(B)(1) through (B)(5). The provisions of 240.4(B) shall not be permitted for tap conductors.
If the length of the tap conductors does not exceed 3 m (10 ft) and the tap conductors comply with all of the following:
- The ampacity of the tap conductors is
- Not less than the combined calculated loads on the circuits supplied by the tap conductors, and
- Not less than the rating of the equipment containing an overcurrent device(s) supplied by the tap conductors or not less than the rating of the overcurrent protective device at the termination of the tap conductors.
Exception to b: Where listed equipment, such as a surge protective device(s) [SPD(s)], is provided with specific instructions on minimum conductor sizing, the ampacity of the tap conductors supplying that equipment shall be permitted to be determined based on the manufacturer's instructions.
- The tap conductors do not extend beyond the switchboard, switchgear, panelboard, disconnecting means, or control devices they supply.
- Except at the point of connection to the feeder, the tap conductors are enclosed in a raceway, which extends from the tap to the enclosure of an enclosed switchboard, switchgear, a panelboard, or control devices, or to the back of an open switchboard.
- For field installations, if the tap conductors leave the enclosure or vault in which the tap is made, the ampacity of the tap conductors is not less than one-tenth of the rating of the overcurrent device protecting the feeder conductors.
Where the length of the tap conductors does not exceed 7.5 m (25 ft) and the tap conductors comply with all the following:
- The ampacity of the tap conductors is not less than one-third of the rating of the overcurrent device protecting the feeder conductors.
- The tap conductors terminate in a single circuit breaker or a single set of fuses that limit the load to the ampacity of the tap conductors. This device shall be permitted to supply any number of additional overcurrent devices on its load side.
- The tap conductors are protected from physical damage by being enclosed in an approved raceway or by other approved means.
Where the tap conductors supply a transformer and comply with all the following conditions:
- The conductors supplying the primary of a transformer have an ampacity at least one-third the rating of the overcurrent device protecting the feeder conductors.
- The conductors supplied by the secondary of the transformer shall have an ampacity that is not less than the value of the primary-to-secondary voltage ratio multiplied by one-third of the rating of the overcurrent