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Chapter 39 Power and Lighting Distribution

ICC user note:
About this chapter: Chapter 39 addresses the "rough-in" stage of construction in which the wiring system is installed and receptacle and lighting outlets placed throughout the dwelling. This chapter covers receptacle outlet spacing, GFCI (ground-fault circuit-interrupter) and AFCI (arc-fault circuit-interrupter) protection, lighting outlet locations, raceway and box fill limitations, box and panel board installation, equipment grounding and flexible cords.

Section E3901 Receptacle Outlets

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E3901.1 General

Outlets for receptacles rated at 125 volts, 15- and 20-amperes shall be provided in accordance with Sections E3901.2 through E3901.11. Receptacle outlets required by this section shall be in addition to any receptacle that is:
  1. Part of a luminaire or appliance;
  2. Located within cabinets or cupboards;
  3. Controlled by a listed wall-mounted control device in accordance with Section E3903.2, Exception 1; or
  4. Located over 5.5 feet (1676 mm) above the floor.
Permanently installed electric baseboard heaters equipped with factory-installed receptacle outlets, or outlets provided as a separate assembly by the baseboard 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. (210.52)

E3901.2 General Purpose Receptacle Distribution

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 Sections E3901.2.1 through E3901.2.4 (see Figure E3901.2).


For SI: 1 foot = 304.8 mm.
FIGURE E3901.2
GENERAL USE RECEPTACLE DISTRIBUTION

E3901.2.1 Spacing

Receptacles shall be installed so that no point measured horizontally along the floor line of any wall space is more than 6 feet (1829 mm), from a receptacle outlet. [210.52(A)(1)]

E3901.2.2 Wall Space

As used in this section, a wall space shall include the following: [210.52(A)(2)]
  1. Any space that is 2 feet (610 mm) or more in width, including space measured around corners, and that is unbroken along the floor line by doorways and similar openings, fireplaces, and fixed cabinets that do not have countertops or similar work surfaces.
  2. The space occupied by fixed panels in exterior walls, excluding sliding panels.
  3. The space created by fixed room dividers such as railings and freestanding bar-type counters.

E3901.2.3 Floor Receptacles

Receptacle outlets in floors shall not be counted as part of the required number of receptacle outlets except where located within 18 inches (457 mm) of the wall. [210.52(A)(3)]

E3901.2.4 Countertop and Similar Work Surface Receptacles Outlets

Receptacles installed for countertop and similar work surfaces as specified in Section E3901.4 shall not be considered as the receptacle outlets required by Section E3901.2. [210.52(A)(4)]

E3901.3 Small Appliance Receptacles

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 Section E3703.2, shall serve all wall and floor receptacle outlets covered by Sections E3901.2 and E3901.4 and those receptacle outlets provided for refrigeration appliances. [210.52(B)(1)]
Exceptions:
  1. In addition to the required receptacles specified by Sections E3901.1 and E3901.2, switched receptacles supplied from a general-purpose 15- or 20-ampere branch circuit as required in Section E3903.2, Exception 1 shall be permitted. [210.52(B)(1) Exception No. 1]
  2. In addition to the required receptacles specified by Section E3901.2, a receptacle outlet to serve a specific appliance shall be permitted to be supplied from an individual branch circuit rated at 15 amperes or greater. [210.52(B)(1) Exception No. 2]

E3901.3.1 Other Outlets Prohibited

The two or more small-appliance branch circuits specified in Section E3901.3 shall serve no other outlets. [210.52(B)(2)]
Exceptions:
  1. A receptacle installed solely for the electrical supply to and support of an electric clock in any of the rooms specified in Section E3901.3. [210.52(B)(2) Exception No.1]
  2. Receptacles installed to provide power for supplemental equipment and lighting on gas-fired ranges, ovens, and counter-mounted cooking units. [210.52(B)(2) Exception No. 2]

E3901.3.2 Limitations

Receptacles installed in a kitchen to serve countertop surfaces shall be supplied by not less 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 Section E3901.3. Additional small-appliance branch circuits shall be permitted to supply receptacle outlets in the kitchen and other rooms specified in Section E3901.3. A small-appliance branch circuit shall not serve more than one kitchen. [210.52(B)(3)]

E3901.4 Countertop and Work Surface Receptacles

In kitchens pantries, breakfast rooms, dining rooms and similar areas of dwelling units, receptacle outlets for countertop and work surfaces that are 12 inches (305 mm) or wider shall be installed in accordance with Sections E3901.4.1 through E3901.4.3 and shall not be considered as the receptacle outlets required in Section E3901.2.
For the purposes of this section, where using multioutlet assemblies, each 12 inches (305 mm) of multioutlet assembly containing two or more receptacles installed in individual or continuous lengths shall be considered to be one receptacle outlet (see Figure E3901.4). [210.52(C)]


For SI: 1 foot = 304.8 mm.
FIGURE E3901.4
COUNTERTOP RECEPTACLES
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E3901.4.1 Wall Spaces

A receptacle outlet shall be installed at each wall countertop and work surface that is 12 inches (305 mm) or wider. Receptacle outlets shall be installed so that no point along the wall line is more than 24 inches (610 mm), measured horizontally, from a receptacle outlet in that space. [210.52(C)(1)]
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 E3901.4.1. [210.52(C)(1) Exception]


For SI: 1 inch = 25.4 mm.

FIGURE E3901.4.1
DETERMINATION OF AREA BEHIND SINK OR RANGE

E3901.4.2 Island and Peninsular Countertops and Work Spaces

Receptacle outlets shall be installed in accordance with the following: [210.52(C)(2)]
  1. At least one receptacle outlet shall be provided for the first 6 feet of length, or fraction thereof, of the countertop or work surface. A minimum of two receptacle outlets shall be provided for any island over 6 feet long.
  2. At least one receptacle outlet shall be located within 2 feet (600 mm) of the outer end of a peninsular countertop or work surface. Additional receptacle outlets shall be permitted to be located as determined by the installer, designer or building owner. The location of the receptacle outlets shall be in accordance with Section E3901.4.3. [210.52(C)(2)(b)]

E3901.4.3 Receptacle Outlet Location

Receptacle outlets rendered not readily accessible by appliances fastened in place, appliance garages, sinks, or rangetops as covered in the exception to Section E3901.4.1, or appliances occupying assigned spaces shall not be considered as these required outlets. Required receptacle outlets shall be located in one or more of the following:
  1. On or above, but not more than 20 inches (508 mm) above, the countertop or work surface.
  2. Receptacle outlet assemblies listed for the use in countertops or work surfaces shall be permitted to be installed in countertops or work surfaces.
  3. Not more than 12 inches (305 mm) below the countertop or work surface. Receptacles installed below a countertop or work surface shall not be located where the countertop or work surface extends more than 6 inches (152 mm) beyond its support base. [210.52(C)(3)]

E3901.5 Appliance Receptacle Outlets

Appliance receptacle outlets installed for specific appliances, such as laundry equipment, shall be installed within 6 feet (1829 mm) of the intended location of the appliance. (210.50(C)]

E3901.6 Bathroom

At least one receptacle outlet shall be installed in bathrooms and such outlet shall be located within 36 inches (914 mm) of the outside edge of each lavatory basin. The receptacle outlet shall be located on a wall or partition that is adjacent to the lavatory basin location, located on the countertop, or installed on the side or face of the basin cabinet. The receptacle shall be located not more than 12 inches (305 mm) below the top of the basin or basin countertop.
Receptacle outlet assemblies installed in countertops shall be listed for the application. [210.52(D)]

E3901.7 Outdoor Outlets

Not less than one receptacle outlet that is readily accessible from grade level and located not more than 6 feet 6 inches (1981 mm) above grade, shall be installed outdoors at the front and back of each dwelling unit having direct access to grade level. Balconies, decks and porches that are accessible from inside within 4 inches (102 mm) horizontally of the dwelling unit shall have at least one receptacle outlet accessible from the balcony, deck or porch. The receptacle shall be located not more than 6 feet 6 inches (1981 mm) above the balcony, deck, or porch surface. [210.52(E)]
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E3901.8 Laundry Areas

Not less than one receptacle outlet shall be installed in areas designated for the installation of laundry equipment.

E3901.9 Basements, Garages and Accessory Buildings

Not less than one receptacle outlet, in addition to any provided for specific equipment, shall be installed in each separate unfinished portion of a basement; in each vehicle bay not more than 5.5 feet (1676 mm) above the floor in attached garages; in each vehicle bay not more than 5.5 feet (1676 mm) above the floor in detached garages that are provided with electric power and in accessory buildings that are provided with electric power. [210.52(G)(1), (2), and (3)]

E3901.10 Hallways

Hallways of 10 feet (3048 mm) or more in length shall have at least one receptacle outlet. The hall length shall be considered the length measured along the centerline of the hall without passing through a doorway. [210.52(H)]

E3901.11 Foyers

Foyers that are not part of a hallway in accordance with Section E3901.10 and that have an area that is greater than 60 square feet (5.57 m2) shall have a receptacle(s) located in each wall space that is 3 feet (914 mm) or more in width. Doorways, door-side windows that extend to the floor, and similar openings shall not be considered as wall space. [210.52(H)]

E3901.12 HVAC Outlet

A 125-volt, single-phase, 15- or 20-ampere-rated receptacle outlet shall be installed at an accessible location for the servicing of heating, air-conditioning and refrigeration equipment. The receptacle shall be located on the same level and within 25 feet (7620 mm) of the heating, air-conditioning and refrigeration equipment. The receptacle outlet shall not be connected to the load side of the HVAC equipment disconnecting means. (210.63)
Exception: A receptacle outlet shall not be required for the servicing of evaporative coolers. (210.63 Exception)

Section E3902 Ground-Fault and Arc-Fault Circuit-Interrupter Protection

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E3902.1 Bathroom Receptacles

125-volt receptacles installed in bathrooms and supplied by single-phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter protection for personnel. [210.8(A)(1)]

E3902.2 Garage and Accessory Building Receptacles

125-volt receptacles installed in garages and grade-level portions of unfinished accessory buildings used for storage or work areas and supplied by single-phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter protection for personnel. [210.8(A)(2)]

E3902.3 Outdoor Receptacles

125-volt receptacles installed outdoors and supplied by single-phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter protection for personnel. [210.8(A)(3)]
Exception: Receptacles as covered in Section E4101.7. [210.8(A)(3) Exception]

E3902.4 Crawl Space Receptacles and Lighting Outlets

Where a crawl space is at or below grade level, 125-volt receptacles installed in such spaces and supplied by single-phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter protection for personnel. Lighting outlets not exceeding 120 volts shall have ground-fault circuit-interrupter protection. [210.8(A)(4), 2108(E)]

E3902.5 Basement Receptacles

125-volt receptacles installed in basements and supplied by single phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter protection for personnel. [210.8(A)(5)]
Exceptions:
  1. A receptacle supplying only a permanently installed fire alarm or burglar alarm system. A receptacle installed in accordance with this exception shall not be considered as meeting the requirement of Section E3901.9. Receptacles installed in accordance with this exception shall not be considered as meeting the requirement of Section E3901.9. [210.8(A)(5) Exception]
  2. Receptacles in walk-out basements are excluded from this requirement.

E3902.6 Kitchen Receptacles

125-volt receptacles that serve countertop surfaces and are supplied by single-phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter protection for personnel. [210.8(A)(6)]

E3902.7 Sink Receptacles

125-volt receptacles that are located within 6 feet (1829 mm) of the top inside edge of the bowl of the sink and supplied by single-phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter protection for personnel. [210.8(A)(7)]

E3902.8 Bathtub or Shower Stall Receptacles

125-volt receptacles that are located within 6 feet (1829 mm) of the outside edge of a bathtub or shower stall and supplied by single-phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter protection for personnel. [210.8(A)(9)]

E3902.9 Laundry Areas

125-volt receptacles installed in laundry areas and supplied by single-phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter protection for personnel. [210.8(A)(10)]

E3902.10 Indoor Damp and Wet Locations

125-volt receptacles installed in indoor damp and wet locations and supplied by single-phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter protection for personnel. [210.8(A)(11)]

E3902.11 Kitchen Dishwasher Branch Circuit

Ground-fault circuit-interrupter protection shall be provided for outlets supplied by branch circuits rated 150 volts or less to ground that supply dishwashers in dwelling unit locations. [422.5 (A)]

E3902.12 Boathouse Receptacles

125-volt receptacles installed in boathouses and supplied by single-phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter protection for personnel. [210.8(A)(8)]

E3902.13 Boat Hoists

Ground-fault circuit-interrupter protection for personnel shall be provided for 240-volt and less outlets that supply boat hoists. [555.9]

E3902.14 Electrically Heated Floors

Ground-fault circuit-interrupter protection for personnel shall be provided for electric heating cables embedded in concrete or poured masonry floors in bathrooms, kitchens and in hydromassage bathtub, spa and hot tub locations. Heating cables installed under floor coverings shall be provided with ground-fault circuit-interrupter protection for personnel. [424.44(E), 424.45(E)]

E3902.15 Crawl Space Lighting Outlets

Lighting outlets not exceeding 120 volts installed in crawl spaces shall have ground-fault circuit-interrupter protection for personnel. [210.8(C)]

E3902.16 Equipment Requiring Servicing

Receptacles installed in accordance with Section E3901.12 shall have ground-fault circuit-interrupter protection. [210.8(E)]

E3902.17 Outdoor Outlets

All outdoor outlets, other than those covered in the exception to Section E3902.3, that are supplied by single-phase branch circuits rated 150 volts to ground or less, 50 amperes or less, shall have ground-fault circuit-interrupter protection for personnel. [210.8(F)]
Exception: Ground-fault circuit-interrupter protection shall not be required on lighting outlets other than those covered in Section E3902.15. [210.8(F) Exception]

E3902.18 Location of Ground-Fault Circuit Interrupters

Ground-fault circuit interrupters shall be installed in a readily accessible location. When determining distance from receptacles, the distance shall be measured as the shortest path the supply cord of an appliance connected to the receptacle would follow without piercing a floor, wall, ceiling, or fixed barrier, or the shortest path without passing through a window. [210.8(A)]

E3902.19 Location of Arc-Fault Circuit Interrupters

Arc-fault circuit interrupters shall be installed in readily accessible locations.

E3902.20 Arc-Fault Circuit Interrupter Protection

In areas other than kitchen and laundry areas, branch circuits that supply 120-volt, single-phase, 15- and 20-ampere outlets installed in family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreations rooms, closets, hallways and similar rooms or areas shall be protected by any of the following: [210.12(A)]
  1. A listed combination-type arc-fault circuit interrupter, installed to provide protection of the entire branch circuit. [210.12(A)(1)]
  2. 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. [210.12(A)(2)]
  3. 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:
    1. The branch-circuit wiring shall be continuous from the branch-circuit overcurrent device to the outlet branch-circuit arc-fault circuit interrupter.
    2. The maximum length of the branch-circuit wiring from the branch-circuit overcurrent device to the first outlet shall not exceed 50 feet (15.2 m) for 14 AWG conductors and 70 feet (21.3 m) for 12 AWG conductors.
    3. The first outlet box on the branch circuit shall be marked to indicate that it is the first outlet on the circuit. [210.12(A)(3)]
  4. 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:
    1. The branch-circuit wiring shall be continuous from the branch-circuit overcurrent device to the outlet branch-circuit arc-fault circuit interrupter.
    2. The maximum length of the branch-circuit wiring from the branch-circuit overcurrent device to the first outlet shall not exceed 50 feet (15.2 m) for 14 AWG conductors and 70 feet (21.3 m) for 12 AWG conductors.
    3. The first outlet box on the branch circuit shall be marked to indicate that it is the first outlet on the circuit.
    4. 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. [210.12(A)(4)]
  5. Where metal raceways, metal wireways, metal auxiliary gutters or Type MC or Type AC cable meeting the applicable requirements of Section E3908.9 with metal boxes, metal conduit bodies and metal enclosures are installed for the portion of the branch circuit between the branch-circuit overcurrent device and the first outlet, a listed outlet branch-circuit type AFCI installed at the first outlet shall be considered as providing protection for the remaining portion of the branch circuit. [210.12(A)(5)]
  6. Where a listed metal or nonmetallic conduit or tubing or Type MC cable is encased in not less than 2 inches (50.8 mm) of concrete for the portion of the branch circuit between the branch-circuit overcurrent device and the first outlet, a listed outlet branch-circuit-type AFCI installed at the first outlet shall be considered as providing protection for the remaining portion of the branch circuit. [210.12(A)(6)]
Exception: AFCI protection shall not be required for an individual branch circuit supplying a fire alarm system where the branch circuit is installed in a metal raceway, metal auxiliary gutter, steel-armored cable, Type MC or Type AC, meeting the requirements of Section E3908.9, with metal boxes, conduit bodies and enclosures.

E3902.21 Arc-Fault Circuit-Interrupter Protection for Branch Circuit Extensions or Modifications

Where branch-circuit wiring is modified, replaced, or extended in any of the areas specified in Section E3902.20, the branch circuit shall be protected by one of the following:
  1. A combination-type AFCI located at the origin of the branch circuit.
  2. An outlet branch-circuit type AFCI located at the first receptacle outlet of the existing branch circuit. [210.12(B)]
Exception: AFCI protection shall not be required where the extension of the existing branch circuit conductors is not more than 6 feet (1.8 m) in length and does not include any additional outlets or devices other than splicing devices. This measurement shall not include the conductors inside an enclosure, cabinet, or junction box. [210.12(B) Exception]

Section E3903 Lighting Outlets

E3903.1 General

Lighting outlets shall be provided in accordance with Sections E3903.2 through E3903.4. [210.70(A)]

E3903.2 Habitable Rooms

At least one lighting outlet controlled by a listed wall-mounted control device shall be installed in every habitable room, kitchen and bathroom. The wall-mounted control device shall be located near an entrance to the room on a wall. [210.70(A)(1)]
Exceptions:
  1. In other than kitchens and bathrooms, one or more receptacles controlled by a listed wall-mounted control device shall be considered equivalent to the required lighting outlet. [210.70(A)(1) Exception No. 1]
  2. Lighting outlets shall be permitted to be controlled by occupancy sensors that are in addition to listed wall-mounted control devices or that are located at a customary wall switch location and equipped with a manual override that will allow the sensor to function as a wall switch. [210.70(A)(1) Exception No. 2]

E3903.3 Additional Locations

At least one lighting outlet controlled by a listed wall-mounted control device shall be installed in hallways, stairways, attached garages, and detached garages with electric power. At least one lighting outlet controlled by a listed wall-mounted control device shall be installed to provide illumination on the exterior side of each outdoor egress door having grade level access, including outdoor egress doors for attached garages and detached garages with electric power. A vehicle door in a garage shall not be considered as an outdoor egress door.

E3903.3.1 Stairway Lighting Outlet Control

Where one or more lighting outlets are installed for interior stairways, there shall be a listed wall-mounted control device at each floor level and landing level that includes an entryway to control the lighting outlets where the stairway between floor levels has six or more risers. Lighting outlets installed to meet this requirement shall not be controlled by the use of listed wall-mounted control devices except where the devices provide the full range of dimming control at each switch location. [210.70(A)(2)]
Exception: In hallways, stairways, and at outdoor egress doors, remote, central, or automatic control of lighting shall be permitted. [210.70(A)(2) Exception]

E3903.4 Storage or Equipment Spaces

In attics, under-floor spaces, utility rooms and basements, at least one lighting outlet shall be installed where these spaces are used for storage or contain equipment requiring servicing. Such lighting outlet shall be controlled by a wall switch or listed wall-mounted control device. A point of control shall be provided at each entry that permits access to the attic or underfloor space, utility room, or basement. Where a lighting outlet is installed for equipment requiring service, the lighting outlet shall be installed at or near the equipment requiring servicing. [210.70(C)]

Section E3904 General Installation Requirements

E3904.1 Electrical Continuity of Metal Raceways and Enclosures

Metal raceways, cable armor and other metal enclosures for conductors shall be mechanically joined together into a continuous electric conductor and shall be connected to all boxes, fittings and cabinets so as to provide effective electrical continuity. Raceways and cable assemblies shall be mechanically secured to boxes, fittings cabinets and other enclosures. (300.10)
Exception: Short sections of raceway used to provide cable assemblies with support or protection against physical damage. (300.10 Exception No. 1)

E3904.2 Mechanical Continuity—Raceways and Cables

Raceways, cable armors and cable sheaths shall be continuous between cabinets, boxes, fittings or other enclosures or outlets. (300.12)
Exception: Short sections of raceway used to provide cable assemblies with support or protection against physical damage. (300.12 Exception No. 1)

E3904.3 Securing and Supporting

Raceways, cable assemblies, boxes, cabinets and fittings shall be securely fastened in place. (300.11)

E3904.3.1 Prohibited Means of Support

Cable wiring methods shall not be used as a means of support for other cables, raceways and nonelectrical equipment. [300.11(D)]

E3904.4 Raceways as Means of Support

Raceways shall be used as a means of support for other raceways, cables or nonelectric equipment only under the following conditions:
  1. Where the raceway or means of support is identified as a means of support; or
  2. Where the raceway contains power supply conductors for electrically controlled equipment and is used to support Class 2 circuit conductors or cables that are solely for the purpose of connection to the control circuits of the equipment served by such raceway; or
  3. Where the raceway is used to support boxes or conduit bodies in accordance with Sections E3906.8.4 and E3906.8.5. [300.11(C)]

E3904.5 Raceway Installations

Raceways shall be installed complete between outlet, junction or splicing points prior to the installation of conductors. (300.18)
Exception: Short sections of raceways used to contain conductors or cable assemblies for protection from physical damage shall not be required to be installed complete between outlet, junction, or splicing points. (300.18 Exception)

E3904.6 Conduit and Tubing Fill

The maximum number of conductors installed in conduit or tubing shall be in accordance with Tables E3904.6(1) through E3904.6(10). (300.17, Chapter 9, Table 1 and Annex C)
TABLE E3904.6(1) (Annex C, Table C.1)
MAXIMUM NUMBER OF CONDUCTORS IN ELECTRICAL METALLIC TUBING (EMT)a
TYPE LETTERS CONDUCTOR SIZE AWG/kcmil TRADE SIZES (inches)
1/2 3/4 1 11/4 11/2 2
RHH, RHW, RHW-2 14 4 7 11 20 27 46
12 3 6 9 17 23 38
10 2 5 8 13 18 30
8 1 2 4 7 9 16
6 1 1 3 5 8 13
4 1 1 2 4 6 10
3 1 1 1 4 5 9
2 1 1 1 3 4 7
1 0 1 1 1 3 5
1/0 0 1 1 1 2 4
2/0 0 1 1 1 2 4
3/0 0 0 1 1 1 3
4/0 0 0 1 1 1 3
TW, THHW, THW, THW-2 14 8 15 25 43 58 96
12 6 11 19 33 45 74
10 5 8 14 24 33 55
8 2 5 8 13 18 30
RHHa, RHWa, RHW-2a 14 6 10 16 28 39 64
12 4 8 13 23 31 51
10 3 6 10 18 24 40
8 1 4 6 10 14 24
RHHa, RHWa, RHW-2a, TW, THW, THHW, THW-2 6 1 3 4 8 11 18
4 1 1 3 6 8 13
3 1 1 3 5 7 12
2 1 1 2 4 6 10
1 1 1 1 3 4 7
1/0 0 1 1 2 3 6
2/0 0 1 1 1 3 5
3/0 0 1 1 1 2 4
4/0 0 0 1 1 1 3
THHN, THWN, THWN-2 14 12 22 35 61 84 138
12 9 16 26 45 61 101
10 5 10 16 28 38 63
8 3 6 9 16 22 36
6 2 4 7 12 16 26
4 1 2 4 7 10 16
3 1 1 3 6 8 13
2 1 1 3 5 7 11
1 1 1 1 4 5 8
1/0 1 1 1 3 4 7
2/0 0 1 1 2 3 6
3/0 0 1 1 1 3 5
4/0 0 1 1 1 2 4
XHH, XHHW, XHHW-2 14 8 15 25 43 58 96
12 6 11 19 33 45 74
10 5 8 14 24 33 55
8 2 5 8 13 18 30
6 1 3 6 10 14 22
4 1 2 4 7 10 16
3 1 1 3 6 8 14
2 1 1 3 5 7 11
1 1 1 1 4 5 8
1/0 1 1 1 3 4 7
2/0 0 1 1 2 3 6
3/0 0 1 1 1 3 5
4/0 0 1 1 1 2 4
For SI: 1 inch = 25.4 mm.
  1. Types RHW and RHW-2 without outer covering.
TABLE E3904.6(2) (Annex C, Table C.2)
MAXIMUM NUMBER OF CONDUCTORS IN ELECTRICAL NONMETALLIC TUBING (ENT)a
TYPE LETTERS CONDUCTOR SIZE AWG/kcmil TRADE SIZES (inches)
1/2 3/4 1 11/4 11/2 2
RHH, RHW, RHW-2 14 3 6 10 19 26 43
12 2 5 9 16 22 36
10 1 4 7 13 17 29
8 1 1 3 6 9 15
6 1 1 3 5 7 12
4 1 1 2 4 6 9
3 1 1 1 3 5 8
2 0 1 1 3 4 7
1 0 1 1 1 3 5
1/0 0 0 1 1 2 4
2/0 0 0 1 1 1 3
3/0 0 0 1 1 1 3
4/0 0 0 1 1 1 2
TW, THHW, THW, THW-2 14 7 13 22 40 55 92
12 5 10 17 31 42 71
10 4 7 13 23 32 52
8 1 4 7 13 17 29
RHHa, RHWa, RHW-2a 14 4 8 15 27 37 61
12 3 7 12 21 29 49
10 3 5 9 17 23 38
8 1 3 5 10 14 23
RHHa, RHWa, RHW-2a, TW, THW, THHW, THW-2 6 1 2 4 7 10 17
4 1 1 3 5 8 13
3 1 1 2 5 7 11
2 1 1 2 4 6 9
1 0 1 1 3 4 6
1/0 0 1 1 2 3 5
2/0 0 1 1 1 3 5
3/0 0 0 1 1 2 4
4/0 0 0 1 1 1 3
THHN, THWN, THWN-2 14 10 18 32 58 80 132
12 7 13 23 42 58 96
10 4 8 15 26 36 60
8 2 5 8 15 21 35
6 1 3 6 11 15 25
4 1 1 4 7 9 15
3 1 1 3 5 8 13
2 1 1 2 5 6 11
THHN, THWN, THWN-2 1 1 1 1 3 5 8
1/0 0 1 1 3 4 7
2/0 0 1 1 2 3 5
3/0 0 1 1 1 3 4
4/0 0 0 1 1 2 4
XHH, XHHW, XHHW-2 14 7 13 22 40 55 92
12 5 10 17 31 42 71
10 4 7 13 23 32 52
8 1 4 7 13 17 29
6 1 3 5 9 13 21
4 1 1 4 7 9 15
3 1 1 3 6 8 13
2 1 1 2 5 6 11
1 1 1 1 3 5 8
1/0 0 1 1 3 4 7
2/0 0 1 1 2 3 6
3/0 0 1 1 1 3 5
4/0 0 0 1 1 2 4
For SI: 1 inch = 25.4 mm.
  1. Types RHW and RHW-2 without outer covering.
TABLE E3904.6(3) (Annex C, Table C.3)
MAXIMUM NUMBER OF CONDUCTORS IN FLEXIBLE METALLIC CONDUIT (FMC)a
TYPE LETTERS CONDUCTOR SIZE AWG/kcmil TRADE SIZES (inches)
1/2 3/4 1 11/4 11/2 2
RHH, RHW, RHW-2 14 3 7 11 17 25 44
12 3 6 9 14 21 37
10 14 5 7 11 17 30
8 1 2 4 6 9 15
6 1 1 3 5 7 12
4 1 1 2 4 5 10
3 1 1 1 3 5 7
2 1 1 1 3 4 7
1 0 1 1 1 2 5
1/0 0 1 1 1 2 4
2/0 0 1 1 1 1 3
3/0 0 0 1 1 1 3
TW, THHW, THW, THW-2 14 9 15 23 36 53 94
12 7 11 18 28 41 72
10 5 8 13 21 30 54
8 3 5 7 11 17 30
RHHa, RHWa, RHW-2a 14 6 10 15 24 35 62
12 5 8 12 19 28 50
10 4 6 10 15 22 39
8 1 4 6 9 13 23
RHHa, RHWa, RHW-2a, TW, THW, THHW, THW-2 6 1 3 4 7 10 18
4 1 1 3 5 7 13
3 1 1 3 4 6 11
2 1 1 2 4 5 10
1 1 1 1 2 4 7
1/0 0 1 1 1 3 6
2/0 0 1 1 1 3 5
3/0 0 1 1 1 2 4
4/0 0 0 1 1 1 3
4/0 0 0 1 1 1 2
THHN, THWN, THWN-2 14 13 22 33 52 76 134
12 9 16 24 38 56 98
10 6 10 15 24 35 62
8 3 6 9 14 20 35
THHN, THWN, THWN-2 6 2 4 6 10 14 25
4 1 2 4 6 9 16
3 1 1 3 5 7 13
2 1 1 3 4 6 11
1 1 1 1 3 4 8
1/0 1 1 1 2 4 7
2/0 0 1 1 1 3 6
3/0 0 1 1 1 2 5
4/0 0 1 1 1 1 4
XHH, XHHW, XHHW-2 14 9 15 23 36 53 94
12 7 11 18 28 41 72
10 5 8 13 21 30 54
8 3 5 7 11 17 30
6 1 3 5 8 12 22
4 1 2 4 6 9 16
3 1 1 3 5 7 13
2 1 1 3 4 6 11
1 1 1 1 3 5 8
1/0 1 1 1 2 4 7
2/0 0 1 1 2 3 6
3/0 0 1 1 1 3 5
4/0 0 1 1 1 2 4
For SI: 1 inch = 25.4 mm.
  1. Types RHW and RHW-2 without outer covering.
TABLE E3904.6(4) (Annex C, Table C.4)
MAXIMUM NUMBER OF CONDUCTORS IN INTERMEDIATE METALLIC CONDUIT (IMC)a
TYPE LETTERS CONDUCTOR SIZE AWG/kcmil TRADE SIZES (inches)
1/2 3/4 1 11/4 11/2 2
RHH, RHW, RHW-2 14 4 8 13 22 30 49
12 4 6 11 18 25 41
10 3 5 8 15 20 33
8 1 3 4 8 10 17
6 1 1 3 6 8 14
4 1 1 3 5 6 11
3 1 1 2 4 6 9
2 1 1 1 3 5 8
1 0 1 1 2 3 5
1/0 0 1 1 1 3 4
2/0 0 1 1 1 2 4
3/0 0 0 1 1 1 3
4/0 0 0 1 1 1 3
TW, THHW, THW, THW-2 14 10 17 27 47 64 104
12 7 13 21 36 49 80
10 5 9 15 27 36 59
8 3 5 8 15 20 33
RHHa, RHWa, RHW-2a 14 6 11 18 31 42 69
12 5 9 14 25 34 56
10 4 7 11 19 26 43
8 2 4 7 12 16 26
RHHa, RHWa, RHW-2a, TW, THW, THHW, THW-2 6 1 3 5 9 12 20
4 1 2 4 6 9 15
3 1 1 3 6 8 13
2 1 1 3 5 6 11
1 1 1 1 3 4 7
1/0 1 1 1 3 4 6
2/0 0 1 1 2 3 5
3/0 0 1 1 1 3 4
4/0 0 1 1 1 2 4
THHN, THWN, THWN-2 14 14 24 39 68 91 149
12 10 17 29 49 67 109
10 6 11 18 31 42 68
8 3 6 10 18 24 39
6 2 4 7 13 17 28
4 1 3 4 8 10 17
3 1 2 4 6 9 15
2 1 1 3 5 7 12
1 1 1 2 4 5 9
1/0 1 1 1 3 4 8
2/0 1 1 1 3 4 6
THHN, THWN, THWN-2 3/0 0 1 1 2 3 5
2/0 0 1 1 1 2 4
XHH, XHHW, XHHW-2 14 10 17 27 47 64 104
12 7 13 21 36 49 80
10 5 9 15 27 36 59
8 3 5 8 15 20 33
6 1 4 6 11 15 24
4 1 3 4 8 11 18
3 1 2 4 7 9 15
2 1 1 3 5 7 12
1 1 1 2 4 5 9
1/0 1 1 1 3 5 8
2/0 1 1 1 3 4 6
3/0 0 1 1 2 3 5
4/0 0 1 1 1 2 4
For SI: 1 inch = 25.4 mm.
  1. Types RHW and RHW-2 without outer covering.
TABLE E3904.6(5) (Annex C, Table C.5)
MAXIMUM NUMBER OF CONDUCTORS IN LIQUID-TIGHT FLEXIBLE NONMETALLIC CONDUIT (FNMC-B)a
TYPE LETTERS CONDUCTOR SIZE AWG/kcmil TRADE SIZES (inches)
3/8 1/2 3/4 1 11/4 11/2 2
RHH, RHW, RHW-2 14 2 4 7 12 21 27 44
12 1 3 6 10 17 22 36
10 1 3 5 8 14 18 29
8 1 1 2 4 7 9 1
6 1 1 1 3 6 7 12
4 0 1 1 2 4 6 9
3 0 1 1 1 4 5 8
2 0 1 1 1 3 4 7
1 0 0 1 1 1 3 5
1/0 0 0 1 1 1 2 4
2/0 0 0 1 1 1 1 3
3/0 0 0 0 1 1 1 3
4/0 0 0 0 1 1 1 2
TW, THHW, THW, THW-2 14 5 9 15 25 44 57 93
12 4 7 12 19 33 43 71
10 3 5 9 14 25 32 53
8 1 3 5 8 14 18 29
RHHa, RHWa, RGW-2a 14 3 6 10 16 29 38 62
12 3 5 8 13 23 30 50
10 1 3 6 10 18 23 39
8 1 1 4 6 11 14 23
RHHa, RHWa, RHW-2a, TW, THW, THHW, THW-2 6 1 1 3 5 8 11 18
4 1 1 1 3 6 8 13
3 1 1 1 3 5 7 11
2 0 1 1 2 4 6 9
1 0 1 1 1 3 4 7
1/0 0 0 1 1 2 3 6
2/0 0 0 1 1 2 3 5
3/0 0 0 1 1 1 2 4
4/0 0 0 0 1 1 1 3
THHN, THWN, THWN-2 14 8 13 22 36 63 81 133
12 5 9 16 26 46 59 97
10 3 6 10 16 29 37 61
8 1 3 6 9 16 21 35
THHN, THWN, THWN-2 6 1 2 4 7 12 15 25
4 1 1 2 4 7 9 15
3 1 1 1 3 6 8 13
2 1 1 1 3 5 7 11
1 0 1 1 1 4 5 8
1/0 0 1 1 1 3 4 7
2/0 0 0 1 1 2 3 6
3/0 0 0 1 1 1 3 5
4/0 0 0 1 1 1 2 4
XHH, XHHW, XHHW-2 14 5 9 15 25 44 57 93
12 4 7 12 19 33 43 71
10 3 5 9 14 25 32 53
8 1 3 5 8 14 18 29
6 1 1 3 6 10 13 22
4 1 1 2 4 7 9 16
3 1 1 1 3 6 8 13
2 1 1 1 3 5 7 11
1 0 1 1 1 4 5 8
1/0 0 1 1 1 3 4 7
2/0 0 0 1 1 2 3 6
3/0 0 0 1 1 1 3 5
4/0 0 0 1 1 1 2 4
For SI: 1 inch = 25.4 mm.
  1. Types RHW and RHW-2 without outer covering.
TABLE E3904.6(6) (Annex C, Table C.6)
MAXIMUM NUMBER OF CONDUCTORS IN LIQUID-TIGHT FLEXIBLE NONMETALLIC CONDUIT (FNMC-A)a
TYPE LETTERS CONDUCTOR SIZE AWG/kcmil TRADE SIZES (inches)
3/8 1/2 3/4 1 11/4 11/2 2
RHH, RHW, RHW-2 14 2 4 7 11 20 27 45
12 1 3 6 9 17 23 38
10 1 3 5 8 13 18 30
8 1 1 2 4 7 9 16
6 1 1 1 3 5 7 13
4 0 1 1 2 4 6 10
3 0 1 1 1 4 5 8
2 0 1 1 1 3 4 7
1 0 0 1 1 1 3 5
1/0 0 0 1 1 1 2 4
2/0 0 0 1 1 1 1 4
3/0 0 0 0 1 1 1 3
4/0 0 0 0 1 1 1 3
TW, THHW, THW, THW-2 14 5 9 15 24 43 58 96
12 4 7 12 19 33 44 74
10 3 5 9 14 24 33 55
8 1 3 5 8 13 18 30
RHHa, RHWa, RHW-2a 14 3 6 10 16 28 38 64
12 3 4 8 13 23 31 51
10 1 3 6 10 18 24 40
8 1 1 4 6 10 14 24
RHHa, RHWa, RHW-2a, TW, THW, THHW, THW-2 6 1 1 3 4 8 11 18
4 1 1 1 3 6 8 13
3 1 1 1 3 5 7 11
2 0 1 1 2 4 6 10
1 0 1 1 1 3 4 7
RHHa, RHWa, RHW-2a, TW, THW, THHW, THW-2 1/0 0 0 1 1 2 3 6
2/0 0 0 1 1 1 3 5
3/0 0 0 1 1 1 2 4
4/0 0 0 0 1 1 1 3
THHN, THWN, THWN-2 14 8 13 22 35 62 83 137
12 5 9 16 25 45 60 100
10 3 6 10 16 28 38 63
8 1 3 6 9 16 22 36
6 1 2 4 6 12 16 26
4 1 1 2 4 7 9 16
3 1 1 1 3 6 8 13
2 1 1 1 3 5 7 11
1 0 1 1 1 4 5 8
1/0 0 1 1 1 3 4 7
2/0 0 0 1 1 2 3 6
3/0 0 0 1 1 1 3 5
4/0 0 0 1 1 1 2 4
XHH, XHHW, XHHW-2 14 5 9 15 24 43 58 96
12 4 7 12 19 33 44 74
10 3 5 9 14 24 33 55
8 1 3 5 8 13 18 30
6 1 1 3 5 10 13 22
4 1 1 2 4 7 10 16
3 1 1 1 3 6 8 14
2 1 1 1 3 5 7 11
1 0 1 1 1 4 5 8
XHH, XHHW, XHHW-2 1/0 0 1 1 1 3 4 7
2/0 0 0 1 1 2 3 6
3/0 0 0 1 1 1 3 5
4/0 0 0 1 1 1 2 4
For SI: 1 inch = 25.4 mm.
  1. Types RHW and RHW-2 without outer covering.
TABLE E3904.6(7) (Annex C, Table C.7)
MAXIMUM NUMBER OF CONDUCTORS IN LIQUID-TIGHT FLEXIBLE METAL CONDUIT (LFMC)a
TYPE LETTERS CONDUCTOR SIZE AWG/kcmil TRADE SIZES (inches)
1/2 3/4 1 11/4 11/2 2
RHH, RHW, RHW-2 14 4 7 12 21 27 44
12 3 6 10 17 22 36
10 3 5 8 14 18 29
8 1 2 4 7 9 15
6 1 1 3 6 7 12
4 1 1 2 4 6 9
3 1 1 1 4 5 8
2 1 1 1 3 4 7
1 0 1 1 1 3 5
1/0 0 1 1 1 2 4
2/0 0 1 1 1 1 3
3/0 0 0 1 1 1 3
4/0 0 0 1 1 1 2
TW, THHW, THW, THW-2 14 9 15 25 44 57 93
12 7 12 19 33 43 71
10 5 9 14 25 32 53
8 3 5 8 14 18 29
RHHa, RHWa, RHW-2a, THHW, THW, THW-2 14 6 10 16 29 38 62
12 5 8 13 23 30 50
10 3 6 10 18 23 39
8 1 4 6 11 14 23
RHHa, RHWa, RHW-2a, TW, THW, THHW, THW-2 6 1 3 5 8 11 18
4 1 1 3 6 8 13
3 1 1 3 5 7 11
2 1 1 2 4 6 9
1 1 1 1 3 4 7
1/0 0 1 1 2 3 6
2/0 0 1 1 2 3 5
3/0 0 1 1 1 2 4
4/0 0 0 1 1 1 3
THHN, THWN, THWN-2 14 13 22 36 63 81 133
12 9 16 26 46 59 97
10 6 10 16 29 37 61
8 3 6 9 16 21 35
6 2 4 7 12 15 25
4 1 2 4 7 9 15
3 1 1 3 6 8 13
2 1 1 3 5 7 11
1 1 1 1 4 5 8
1/0 1 1 1 3 4 7
2/0 0 1 1 2 3 6
3/0 0 1 1 1 3 5
4/0 0 1 1 1 2 4
XHH, XHHW, XHHW-2 14 9 15 25 44 57 93
12 7 12 19 33 43 71
10 5 9 14 25 32 53
8 3 5 8 14 18 29
XHH, XHHW, XHHW-2 6 1 3 6 10 13 22
4 1 2 4 7 9 16
3 1 1 3 6 8 13
2 1 1 3 5 7 11
1 1 1 1 4 5 8
1/0 1 1 1 3 4 7
2/0 0 1 1 2 3 6
3/0 0 1 1 1 3 5
4/0 0 1 1 1 2 4
For SI: 1 inch = 25.4 mm.
  1. Types RHW and RHW-2 without outer covering.
TABLE E3904.6(8) (Annex C, Table C.8)
MAXIMUM NUMBER OF CONDUCTORS IN RIGID METAL CONDUIT (RMC)a
TYPE LETTERS CONDUCTOR SIZE AWG/kcmil TRADE SIZES (inches)
1/2 3/4 1 11/4 11/2 2
RHH, RHW, RHW-2 14 4 7 12 21 28 46
12 3 6 10 17 23 38
10 3 5 8 14 19 31
8 1 2 4 7 10 16
6 1 1 3 6 8 13
4 1 1 2 4 6 10
3 1 1 2 4 5 9
2 1 1 1 3 4 7
1 0 1 1 1 3 5
1/0 0 1 1 1 2 4
2/0 0 1 1 1 2 4
3/0 0 0 1 1 1 3
4/0 0 0 1 1 1 3
TW, THHW, THW, THW-2 14 9 15 25 44 59 98
12 7 12 19 33 45 75
10 5 9 14 25 34 56
8 3 5 8 14 19 31
RHHa, RHWa, RHW-2a 14 6 10 17 29 39 65
12 5 8 13 23 32 52
10 3 6 10 18 25 41
8 1 4 6 11 15 24
RHHa, RHWa, RHW-2a, TW, THW, THHW, THW-2 6 1 3 5 8 11 18
4 1 1 3 6 8 14
3 1 1 3 5 7 12
2 1 1 2 4 6 10
1 1 1 1 3 4 7
1/0 0 1 1 2 3 6
2/0 0 1 1 2 3 5
3/0 0 1 1 1 2 4
4/0 0 0 1 1 1 3
THHN, THWN, THWN-2 14 13 22 36 63 85 140
12 9 16 26 46 62 102
10 6 10 17 29 39 64
8 3 6 9 16 22 37
6 2 4 7 12 16 27
4 1 2 4 7 10 16
3 1 1 3 6 8 14
2 1 1 3 5 7 11
1 1 1 1 4 5 8
THHN, THWN, THWN-2 1/0 1 1 1 3 4 7
2/0 0 1 1 2 3 6
3/0 0 1 1 1 3 5
4/0 0 1 1 1 2 4
XHH, XHHW, XHHW-2 14 9 15 25 44 59 98
12 7 12 19 33 45 75
10 5 9 14 25 34 56
8 3 5 8 14 19 31
6 1 3 6 10 14 23
4 1 2 4 7 10 16
3 1 1 3 6 8 14
2 1 1 3 5 7 12
1 1 1 1 4 5 9
1/0 1 1 1 3 4 7
2/0 0 1 1 2 3 6
3/0 0 1 1 1 3 5
4/0 0 1 1 1 2 4
For SI: 1 inch = 25.4 mm.
  1. Types RHW and RHW-2 without outer covering.
TABLE E3904.6(9) (Annex C, Table C.9)
MAXIMUM NUMBER OF CONDUCTORS IN RIGID PVC CONDUIT, SCHEDULE 80 (PVC-80)a
TYPE LETTERS CONDUCTOR SIZE AWG/kcmil TRADE SIZES (inches)
1/2 3/4 1 11/4 11/2 2
RHH, RHW, RHW-2 14 3 5 9 17 23 39
12 2 4 7 14 19 32
10 1 3 6 11 15 26
8 1 1 3 6 8 13
6 1 1 2 4 6 11
4 1 1 1 3 5 8
3 0 1 1 3 4 7
2 0 1 1 3 4 6
1 0 1 1 1 2 4
1/0 0 0 1 1 1 3
2/0 0 0 1 1 1 3
3/0 0 0 1 1 1 3
4/0 0 0 0 1 1 2
TW, THHW, THW, THW-2 14 6 11 20 35 49 82
12 5 9 15 27 38 63
10 3 6 11 20 28 47
8 1 3 6 11 15 26
RHHa, RHWa, RHW-2a 14 4 8 13 23 32 55
12 3 6 10 19 26 44
10 2 5 8 15 20 34
8 1 3 5 9 12 20
RHHa, RHWa, RHW-2a, TW, THW, THHW, THW-2 6 1 1 3 7 9 16
4 1 1 3 5 7 12
3 1 1 2 4 6 10
2 1 1 1 3 5 8
1 0 1 1 2 3 6
1/0 0 1 1 1 3 5
RHHa, RHWa, RHW-2a, TW, THW, THHW, THW-2 2/0 0 1 1 1 2 4
3/0 0 0 1 1 1 3
4/0 0 0 1 1 1 3
THHN, THWN, THWN-2 14 9 17 28 51 70 118
12 6 12 20 37 51 86
10 4 7 13 23 32 54
8 2 4 7 13 18 31
6 1 3 5 9 13 22
4 1 1 3 6 8 14
3 1 1 3 5 7 12
2 1 1 2 4 6 10
1 0 1 1 3 4 7
1/0 0 1 1 2 3 6
2/0 0 1 1 1 3 5
3/0 0 1 1 1 2 4
4/0 0 0 1 1 1 3
XHH, XHHW, XHHW-2 14 6 11 20 35 49 82
12 5 9 15 27 38 63
10 3 6 11 20 28 47
8 1 3 6 11 15 26
6 1 2 4 8 11 19
XHH, XHHW, XHHW-2 14 6 11 20 35 49 82
12 5 9 15 27 38 63
10 3 6 11 20 28 47
8 1 3 6 11 15 26
6 1 2 4 8 11 19
4 1 1 3 6 8 14
3 1 1 3 5 7 12
2 1 1 2 4 6 10
1 0 1 1 3 4 7
1/0 0 1 1 2 3 6
2/0 0 1 1 1 3 5
3/0 0 1 1 1 2 4
4/0 0 0 1 1 1 3
For SI: 1 inch = 25.4 mm.
  1. Types RHW and RHW-2 without outer covering.
TABLE E3904.6(10) (Annex C, Table C.10)
MAXIMUM NUMBER OF CONDUCTORS IN RIGID PVC CONDUIT SCHEDULE 40 (PVC-40)a
TYPE LETTERS CONDUCTOR SIZE AWG/kcmil TRADE SIZES (inches)
1/2 3/4 1 11/4 11/2 2
RHH, RHW, RHW-2 14 4 7 11 20 27 45
12 3 5 9 16 22 37
10 2 4 7 13 18 30
8 1 2 4 7 9 15
6 1 1 3 5 7 12
4 1 1 2 4 6 10
3 1 1 1 4 5 8
2 1 1 1 3 4 7
1 0 1 1 1 3 5
1/0 0 1 1 1 2 4
2/0 0 0 1 1 1 3
3/0 0 0 1 1 1 3
4/0 0 0 1 1 1 2
TW, THHW, THW, THW-2 14 8 14 24 42 57 94
12 6 11 18 32 44 72
10 4 8 13 24 32 54
8 2 4 7 13 18 30
RHHa, RHWa, RHW-2a 14 5 9 16 28 38 63
12 4 8 13 22 30 50
10 3 6 10 17 24 39
8 1 3 6 10 14 23
RHHa, RHWa, RHW-2a, TW, THW, THHW, THW-2 6 1 2 4 8 11 18
4 1 1 3 6 8 13
3 1 1 3 5 7 11
2 1 1 2 4 6 10
1 0 1 1 3 4 7
1/0 0 1 1 2 3 6
2/0 0 1 1 1 3 5
3/0 0 1 1 1 2 4
4/0 0 0 1 1 1 3
THHN, THWN, THWN-2 14 11 21 34 60 82 135
12 8 15 25 43 59 99
10 5 9 15 27 37 62
8 3 5 9 16 21 36
THHN, THWN, THWN-2 6 1 4 6 11 15 26
4 1 2 4 7 9 16
3 1 1 3 6 8 13
2 1 1 3 5 7 11
1 1 1 1 3 5 8
1/0 1 1 1 3 4 7
2/0 0 1 1 2 3 6
3/0 0 1 1 1 3 5
4/0 0 1 1 1 2 4
XHH, XHHW, XHHW-2 14 8 14 24 42 57 94
12 6 11 18 32 44 72
10 4 8 13 24 32 54
8 2 4 7 13 18 30
6 1 3 5 10 13 22
4 1 2 4 7 9 16
3 1 1 3 6 8 13
2 1 1 3 5 7 11
1 1 1 1 3 5 8
1/0 1 1 1 3 4 7
2/0 0 1 1 2 3 6
3/0 0 1 1 1 3 5
4/0 0 1 1 1 2 4
For SI: 1 inch = 25.4 mm.
  1. Types RHW and RHW-2 without outer covering.

E3904.7 Air Handling-Stud Cavity and Joist Spaces

Where wiring methods having a nonmetallic covering pass through stud cavities and joist spaces used for air handling, such wiring shall pass through such spaces perpendicular to the long dimension of the spaces. [300.22(C) Exception]

Section E3905 Boxes, Conduit Bodies and Fittings

E3905.1 Box, Conduit Body or Fitting—Where Required

A box or conduit body shall be installed at each conductor splice point, outlet, switch point, junction point and pull point except as otherwise permitted in Sections E3905.1.1 through E3905.1.6.
Fittings and connectors shall be used only with the specific wiring methods for which they are designed and listed. (300.15)

E3905.1.1 Equipment

An integral junction box or wiring compartment that is part of listed equipment shall be permitted to serve as a box or conduit body. [300.15(B)]

E3905.1.2 Protection

A box or conduit body shall not be required where cables enter or exit from conduit or tubing that is used to provide cable support or protection against physical damage. A fitting shall be provided on the end(s) of the conduit or tubing to protect the cable from abrasion. [300.15(C)]

E3905.1.3 Integral Enclosure

A wiring device with integral enclosure identified for the use, having brackets that securely fasten the device to walls or ceilings of conventional on-site frame construction, for use with nonmetallic-sheathed cable, shall be permitted in lieu of a box or conduit body. [300.15(E)]

E3905.1.4 Fitting

A fitting identified for the use shall be permitted in lieu of a box or conduit body where such fitting is accessible after installation and does not contain spliced or terminated conductors. [300.15(F)]

E3905.1.5 Buried Conductors

Splices and taps in buried conductors and cables shall not be required to be enclosed in a box or conduit body where installed in accordance with Section E3803.4.

E3905.1.6 Luminaires

Where a luminaire is listed to be used as a raceway, a box or conduit body shall not be required for wiring installed therein. [300.15(J)]

E3905.2 Metal Boxes

Metal boxes shall be grounded and bonded in accordance with Section E3908. (314.4)

E3905.3 Nonmetallic Boxes

Nonmetallic boxes shall be used only with nonmetallic raceways, cabled wiring methods with entirely nonmetallic sheaths, flexible cords and nonmetallic raceways. (314.3)
Exceptions:
  1. Where internal bonding means are provided between all entries, nonmetallic boxes shall be permitted to be used with metal raceways and metal-armored cables. (314.3 Exception No. 1)
  2. Where integral bonding means with a provision for attaching an equipment grounding jumper inside the box are provided between all threaded entries in nonmetallic boxes listed for the purpose, nonmetallic boxes shall be permitted to be used with metal raceways and metal-armored cables. (314.3 Exception No. 2)

E3905.3.1 Nonmetallic-Sheathed Cable Entering Boxes

Where nonmetallic-sheathed cable or other cable assemblies with nonmetallic sheaths are used, the cable assembly, including the sheath, shall extend into the box not less than 1/4 inch (6.4 mm) through a cable knockout opening. The cable sheath shall extend beyond the cable clamp. Wiring methods shall be secured to the boxes. [314.17(B)(2)]
Exception: Where nonmetallic-sheathed cable is used with boxes not larger than a nominal size of 21/4 inches by 4 inches (57 mm by 102 mm) mounted in walls or ceilings, and where the cable is fastened within 8 inches (203 mm) of the box measured along the sheath, and where the sheath extends through a cable knockout not less than 1/4 inch (6.4 mm), securing the cable to the box shall not be required. [314.17(B)(2) Exception]

E3905.3.2 Conductor Rating

Nonmetallic boxes shall be suitable for the lowest temperature-rated conductor entering the box. [314.17(B)(4)]

E3905.4 Minimum Depth of Boxes for Outlets, Devices, and Utilization Equipment

Outlet and device boxes shall have an approved depth to allow equipment installed within them to be mounted properly and without the likelihood of damage to conductors within the box. (314.24)

E3905.4.1 Outlet Boxes Without Enclosed Devices or Utilization Equipment

Outlet boxes that do not enclose devices or utilization equipment shall have an internal depth of not less than 1/2 inch (12.7 mm). [314.24(A)]

E3905.4.2 Utilization Equipment

Outlet and device boxes that enclose devices or utilization equipment shall have a minimum internal depth that accommodates the rearward projection of the equipment and the size of the conductors that supply the equipment. The internal depth shall include that of any extension boxes, plaster rings, or raised covers. The internal depth shall comply with all of the applicable provisions that follow: [314.24(B)]
  1. Large equipment. Boxes that enclose devices or utilization equipment that projects more than 17/8 inches (48 mm) rearward from the mounting plane of the box shall have a depth that is not less than the depth of the equipment plus 1/4 inch (6.4 mm). [314.24(B)(1)]
  2. Conductors larger than 4 AWG. Boxes that enclose devices or utilization equipment supplied by conductors larger than 4 AWG shall be identified for their specific function. Devices or utilization equipment supplied by conductors larger than 4 AWG shall be permitted to be mounted on or in junction and pull boxes larger than 100 cubic inches (1650 cm3) if the spacing at the terminals meets the requirements of Section E3907.9. [314.24(B)(2) and Exception]
  3. Conductors 8, 6, or 4 AWG. Boxes that enclose devices or utilization equipment supplied by 8, 6, or 4 AWG conductors shall have an internal depth that is not less than 21/16 inches (52.4 mm). [314.24(B)(3)]
  4. Conductors 12 or 10 AWG. Boxes that enclose devices or utilization equipment supplied by 12 or 10 AWG conductors shall have an internal depth that is not less than 13/16 inches (30.2 mm). Where the equipment projects rearward from the mounting plane of the box by more than 1 inch (25.4 mm), the box shall have a depth that is not less than that of the equipment plus 1/4 inch (6.4 mm). [314.24(B)(4)]
  5. Conductors 14 AWG and smaller. Boxes that enclose devices or utilization equipment supplied by 14 AWG or smaller conductors shall have a depth that is not less than 15/16 inch (23.8 mm). [314.24(B)(5)]
Exception: Utilization equipment that is listed to be installed with specified boxes shall be permitted. [314.24(B)(1)—(5) Exception]

E3905.5 Boxes Enclosing Flush-Mounted Devices or Flush Equipment

Boxes enclosing flush-mounted devices or flush equipment shall be of such design that the devices or equipment are completely enclosed at the back and all sides and shall provide support for the devices or equipment. Screws for supporting the box shall not be used for attachment of the device or equipment contained therein. (314.19)

E3905.6 Boxes at Luminaire Outlets

Outlet boxes used at luminaire or lampholder outlets shall be designed for the support of luminaires and lampholders and shall be installed as required by Section E3904.3. [314.27(A)]

E3905.6.1 Vertical Surface Outlets

Boxes used at luminaire or lampholder outlets in or on a vertical surface shall be identified and marked on the interior of the box to indicate the maximum weight of the luminaire or lamp holder that is permitted to be supported by the box if other than 50 pounds (22.7 kg). [314.27(A)(1)]
Exception: A vertically mounted luminaire or lampholder weighing not more than 6 pounds (2.7 kg) shall be permitted to be supported on other boxes or plaster rings that are secured to other boxes, provided that the luminaire or its supporting yoke is secured to the box with not fewer than two No. 6 or larger screws. [314.27(A)(1) Exception]

E3905.6.2 Ceiling Outlets

For outlets used exclusively for lighting, the box shall be designed or installed so that a luminaire or lampholder can be attached. Such boxes shall be capable of supporting a luminaire weighing up to 50 pounds (22.7 kg). A luminaire that weighs more than 50 pounds (22.7 kg) shall be supported independently of the outlet box, unless the outlet box is listed for not less than the weight to be supported. The interior of the box shall be marked by the manufacturer to indicate the maximum weight that the box is permitted to support. [314.27(A)(2)]

E3905.6.3 Separable Attachment Fittings

Outlet boxes required in Section E3905.6 shall be permitted to support listed locking support and mounting receptacles used in combination with compatible attachment fittings. The combination shall be identified for the support of equipment within the weight and mounting orientation limits of the listing. Where the supporting receptacle is installed within a box, it shall be included in the fill calculation covered in Section E3905.12.1.

E3905.7 Floor Boxes

Where outlet boxes for receptacles are installed in the floor, such boxes shall be listed specifically for that application. [314.27(B)]

E3905.8 Boxes at Fan Outlets

Outlet boxes and outlet box systems used as the sole support of ceiling-suspended fans (paddle) shall be marked by their manufacturer as suitable for this purpose and shall not support ceiling-suspended fans (paddle) that weigh more than 70 pounds (31.8 kg). For outlet boxes and outlet box systems designed to support ceiling-suspended fans (paddle) that weigh more than 35 pounds (15.9 kg), the required marking shall include the maximum weight to be supported.
Outlet boxes mounted in the ceilings of habitable rooms in a location acceptable for the installation of a ceiling-suspended (paddle) fan shall comply with one of the following:
  1. Listed for sole support of ceiling-suspended (paddle) fans.
  2. An outlet box complying with the applicable requirements of Section E3905.6 and providing access to structural framing capable of supporting of a ceiling-suspended (paddle) fan bracket or equipment. [314.27(C)]

E3905.9 Utilization Equipment

Boxes used for the support of utilization equipment other than ceiling-suspended (paddle) fans shall meet the requirements of Sections E3905.6.1 and E3905.6.2 for the support of a luminaire that is the same size and weight. [314.27(D)]
Exception: Utilization equipment weighing not more than 6 pounds (2.7 kg) shall be permitted to be supported on other boxes or plaster rings that are secured to other boxes, provided that the equipment or its supporting yoke is secured to the box with not fewer than two No. 6 or larger screws. [314.27(D) Exception]

E3905.10 Conduit Bodies and Junction, Pull and Outlet Boxes to Be Accessible

Conduit bodies and junction, pull and outlet boxes shall be installed so that the wiring therein can be accessed without removing any part of the building or structure or, in underground circuits, without excavating sidewalks, paving, earth or other substance used to establish the finished grade. [314.29(A) & (B)]
Exception: Boxes covered by gravel, light aggregate or noncohesive granulated soil shall be listed for the application, and the box locations shall be effectively identified and access shall be provided for excavation. [314.29(B) Exception]

E3905.11 Damp or Wet Locations

In damp or wet locations, boxes, conduit bodies and fittings shall be placed or equipped so as to prevent moisture from entering or accumulating within the box, conduit body or fitting. Boxes, conduit bodies and fittings installed in wet locations shall be listed for use in wet locations.
Where drainage openings are installed in the field in boxes or conduit bodies listed for use in damp or wet locations, such openings shall be approved, not smaller than 1/8 inch (3 mm) and not larger than 1/4 inch (6.4 mm). For listed drain fittings, larger openings are permitted where installed in the field in accordance with the manufacturer's instructions. (314.15)

E3905.12 Number of Conductors in Outlet, Device, and Junction Boxes, and Conduit Bodies

Boxes and conduit bodies shall be of an approved size to provide free space for all enclosed conductors. In no case shall the volume of the box, as calculated in Section E3905.12.1, be less than the box fill calculation as calculated in Section E3905.12.2. The minimum volume for conduit bodies shall be as calculated in Section E3905.12.3. The provisions of this section shall not apply to terminal housings supplied with motors or generators. (314.16)

E3905.12.1 Box Volume Calculations

The volume of a wiring enclosure (box) shall be the total volume of the assembled sections, and, where used, the space provided by plaster rings, domed covers, extension rings, etc., that are marked with their volume in cubic inches or are made from boxes the dimensions of which are listed in Table E3905.12.1. Where a box is provided with one or more securely installed barriers, the volume shall be apportioned to each of the resulting spaces. Each barrier, if not marked with its volume, shall be considered to take up to 0.5 cubic inch (8.2 cm3) if metal, and 1.0 cubic inch (16.4 cm3) if nonmetallic. [314.16(A)]

TABLE E3905.12.1 [Table 314.16(A)]
MAXIMUM NUMBER OF CONDUCTORS IN METAL BOXESa
BOX DIMENSIONS
(inches trade size and type)		 MAXIMUM CAPACITY
(cubic inches)		 MAXIMUM NUMBER OF CONDUCTORSa
18 Awg 16 Awg 14 Awg 12 Awg 10 Awg 8 Awg 6 Awg
4 × 11/4 round or octagonal 12.5 8 7 6 5 5 4 2
4 × 11/2 round or octagonal 15.5 10 8 7 6 6 5 3
4 × 21/8 round or octagonal 21.5 14 12 10 9 8 7 4
4 × 11/4 square 18.0 12 10 9 8 7 6 3
4 × 11/2 square 21.0 14 12 10 9 8 7 4
4 × 21/8 square 30.3 20 17 15 13 12 10 6
411/16 × 11/4 square 25.5 17 14 12 11 10 8 5
411/16 × 11/2 square 29.5 19 16 14 13 11 9 5
411/16 × 21/8 square 42.0 28 24 21 18 16 14 8
3 × 2 × 11/2 device 7.5 5 4 3 3 3 2 1
3 × 2 × 2 device 10.0 6 5 5 4 4 3 2
3 × 2 × 21/4 device 10.5 7 6 5 4 4 3 2
3 × 2 × 21/2 device 12.5 8 7 6 5 5 4 2
3 × 2 × 23/4 device 14.0 9 8 7 6 5 4 2
3 × 2 × 31/2 device 18.0 12 10 9 8 7 6 3
4 × 21/8 × 11/2 device 10.3 6 5 5 4 4 3 2
4 × 21/8 × 17/8 device 13.0 8 7 6 5 5 4 2
4 × 21/8 × 21/8 device 14.5 9 8 7 6 5 4 2
33/4 × 2 × 21/2 masonry box/gang 14.0 9 8 7 6 5 4 2
33/4 × 2 × 31/2 masonry box/gang 21.0 14 12 10 9 8 7 4
For SI: 1 inch = 25.4 mm, 1 cubic inch = 16.4 cm3.
  1. Where volume allowances are not required by Sections E3905.12.2.2 through E3905.12.2.5.

E3905.12.1.1 Standard Boxes

The volumes of standard boxes that are not marked with a cubic-inch capacity shall be as given in Table E3905.12.1. [314.16(A)(1)]

E3905.12.1.2 Other Boxes

Boxes 100 cubic inches (1640 cm3) or less, other than those described in Table E3905.12.1, and nonmetallic boxes shall be durably and legibly marked by the manufacturer with their cubic-inch capacity. Boxes described in Table E3905.12.1 that have a larger cubic inch capacity than is designated in the table shall be permitted to have their cubic-inch capacity marked as required by this section. [314.16(A)(2)]

E3905.12.2 Box Fill Calculations

The volumes in Section E3905.12.2.1 through Section E3905.12.2.5, as applicable, shall be added together. No allowance shall be required for small fittings such as locknuts and bushings. Each space within a box installed with a barrier shall be calculated separately. [314.16(B)]

E3905.12.2.1 Conductor Fill

Each conductor that originates outside the box and terminates or is spliced within the box shall be counted once, and each conductor that passes through the box without splice or termination shall be counted once. Each loop or coil of unbroken conductor having a length equal to or greater than twice that required for free conductors by Section E3406.11.3, shall be counted twice. The conductor fill, in cubic inches, shall be computed using Table E3905.12.2.1. A conductor, no part of which leaves the box, shall not be counted. [314.16(B)(1)]
Exception: An equipment grounding conductor or not more than four fixture wires smaller than No. 14, or both, shall be permitted to be omitted from the calculations where such conductors enter a box from a domed fixture or similar canopy and terminate within that box. [314.16(B)(1) Exception]

TABLE E3905.12.2.1 [Table 314.16(B)]
VOLUME ALLOWANCE REQUIRED PER CONDUCTOR
SIZE OF CONDUCTOR FREE SPACE WITHIN BOX FOR EACH CONDUCTOR (cubic inches)
18 AWG
 1.50
16 AWG
 1.75
14 AWG
 2.00
12 AWG
 2.25
10 AWG
 2.50
8 AWG
 3.00
6 AWG
 5.00
For SI: 1 cubic inch = 16.4 cm3.

E3905.12.2.2 Clamp Fill

Where one or more internal cable clamps, whether factory or field supplied, are present in the box, a single volume allowance in accordance with Table E3905.12.2.1 shall be made based on the largest conductor present in the box. An allowance shall not be required for a cable connector having its clamping mechanism outside of the box.
A clamp assembly that incorporates a cable termination for the cable conductors shall be listed and marked for use with specific nonmetallic boxes. Conductors that originate within the clamp assembly shall be included in conductor fill calculations provided in Section E3905.12.2.1 as though they entered from outside of the box. The clamp assembly shall not require a fill allowance, but, the volume of the portion of the assembly that remains within the box after installation shall be excluded from the box volume as marked in accordance with Section E3905.12.1.2. [314.16(B)(2)]

E3905.12.2.3 Support Fittings Fill

Where one or more fixture studs or hickeys are present in the box, a single volume allowance in accordance with Table E3905.12.2.1 shall be made for each type of fitting based on the largest conductor present in the box. [314.16(B)(3)]

E3905.12.2.4 Device or Equipment Fill

For each yoke or strap containing one or more devices or equipment, a double volume allowance in accordance with Table E3905.12.2.1 shall be made for each yoke or strap based on the largest conductor connected to a device(s) or equipment supported by that yoke or strap. For a device or utilization equipment that is wider than a single 2-inch (51 mm) device box as described in Table E3905.12.1, a double volume allowance shall be made for each ganged portion required for mounting of the device or equipment. [314.16(B)(4)]

E3905.12.2.5 Equipment Grounding Conductor Fill

Where up to four equipment grounding conductors or equipment bonding jumpers enter a box, a single volume allowance in accordance with Table E3905.12.2.1 shall be made based on the largest equipment grounding conductor or equipment bonding jumper entering the box. A one-quarter volume allowance shall be made for each additional equipment grounding conductor or equipment bonding jumper that enters the box, based on the largest equipment grounding conductor or equipment bonding conductor. [314.16(B)(5)]

E3905.12.3 Conduit Bodies

Conduit bodies enclosing 6 AWG conductors or smaller, other than short-radius conduit bodies, shall have a cross-sectional area not less than twice the cross-sectional area of the largest conduit or tubing to which they can be attached. The maximum number of conductors permitted shall be the maximum number permitted by Section E3904.6 for the conduit to which it is attached. [314.16(C)(1)]

E3905.12.3.1 Splices, Taps or Devices

Only those conduit bodies that are durably and legibly marked by the manufacturer with their cubic inch capacity shall be permitted to contain splices, taps or devices. The maximum number of conductors shall be calculated using the same procedure for similar conductors in other than standard boxes. [314.16(C)(2)]

E3905.12.3.2 Short-Radius Conduit Bodies

Conduit bodies such as capped elbows and service-entrance elbows that enclose conductors 6 AWG or smaller and that are only intended to enable the installation of the raceway and the contained conductors, shall not contain splices, taps, or devices and shall be of sufficient size to provide free space for all conductors enclosed in the conduit body. [314.16(C)(3)]

Section E3906 Installation of Boxes, Conduit Bodies and Fittings

E3906.1 Conductors Entering Boxes, Conduit Bodies or Fittings

Conductors entering boxes, conduit bodies or fittings shall be protected from abrasion. (314.17)

E3906.1.1 Insulated Fittings

Where raceways contain 4 AWG or larger insulated circuit conductors and these conductors enter a cabinet, box enclosure, or raceway, the conductors shall be protected in accordance with any of the following: [300.4(G)]
  1. An identified fitting providing a smoothly rounded insulating surface. Conduit bushings constructed wholly of insulating material shall not be used to secure a fitting or raceway.
  2. A listed metal fitting that has smoothly rounded edges.
  3. Separation from the fitting or raceway using an identified insulating material that is securely fastened in place.
  4. Threaded hubs or bosses that are an integral part of a cabinet, box, enclosure, or raceway providing a smoothly rounded or flared entry for conductors.
Insulating fittings or insulating material shall have a temperature rating not less than the insulation temperature rating of the installed conductors. [300.4(G)]

E3906.2 Openings

Openings through which conductors enter shall be closed in a manner identified for the application. [314.17(A)]

E3906.3 Metal Boxes and Conduit Bodies

Where raceway is installed with metal boxes, or conduit bodies, the raceway shall be secured to such boxes and conduit bodies. [314.17(B)(1)]

E3906.4 Unused Openings

Unused openings other than those intended for the operation of equipment, those intended for mounting purposes, or those permitted as part of the design for listed equipment, shall be closed to afford protection substantially equivalent to that of the wall of the equipment. Metal plugs or plates used with nonmetallic boxes or conduit bodies shall be recessed at least 1/4 inch (6.4 mm) from the outer surface of the box or conduit body. [110.12(A)]

E3906.5 Flush-Mounted Installations

Installations within or behind a surface of concrete, tile, gypsum, plaster or other noncombustible material, including boxes employing a flush-type cover or faceplate shall be made so that the front edge of the box, plaster ring, extension ring, or listed extender will be set back from the finished surface not more than 1/4 inch (6.4 mm). Installations within a surface of wood or other combustible material, boxes, plaster rings, extension rings and listed extenders shall extend to the finished surface or project therefrom. (314.20)

E3906.6 Noncombustible Surfaces

Openings in noncombustible surfaces that accommodate boxes employing a flush-type cover or faceplate shall be made so that there are no gaps or open spaces greater than 1/8 inch (3.2 mm) around the edge of the box. (314.21)

E3906.7 Surface Extensions

Surface extensions shall be made by mounting and mechanically securing an extension ring over the box. (314.22)
Exception: A surface extension shall be permitted to be made from the cover of a flush-mounted box where the cover is designed so it is unlikely to fall off, or be removed if its securing means becomes loose. The wiring method shall be flexible for an approved length that permits removal of the cover and provides access to the box interior and shall be arranged so that any bonding or grounding continuity is independent of the connection between the box and cover. (314.22 Exception)

E3906.8 Supports

Boxes and enclosures shall be supported in accordance with one or more of the provisions in Sections E3906.8.1 through E3906.8.6. (314.23)

E3906.8.1 Surface Mounting

An enclosure mounted on a building or other surface shall be rigidly and securely fastened in place. If the surface does not provide rigid and secure support, additional support in accordance with other provisions of Section E3906.8 shall be provided. [314.23(A)]

E3906.8.2 Structural Mounting

An enclosure supported from a structural member or from grade shall be rigidly supported either directly, or by using a metal, polymeric or wood brace. [314.23(B)]

E3906.8.2.1 Nails and Screws

Nails and screws, where used as a fastening means, shall secure boxes by using brackets on the outside of the enclosure, or by using mounting holes in the back or one or more sides of the enclosure, or they shall pass through the interior within 1/4 inch (6.4 mm) of the back or ends of the enclosure. Screws shall not be permitted to pass through the box except where exposed threads in the box are protected by an approved means to avoid abrasion of conductor insulation. Mounting holes made in the field shall be field approved. [314.23(B)(1)]

E3906.8.2.2 Braces

Metal braces shall be protected against corrosion and formed from metal that is not less than 0.020 inch (0.508 mm) thick uncoated. Wood braces shall have a cross section not less than nominal 1 inch by 2 inches (25.4 mm by 51 mm). Wood braces in wet locations shall be treated for the conditions. Polymeric braces shall be identified as being suitable for the use. [314.23(B)(2)]

E3906.8.3 Mounting in Finished Surfaces

An enclosure mounted in a finished surface shall be rigidly secured there to by clamps, anchors, or fittings identified for the application. [314.23(C)]

E3906.8.4 Raceway Supported Enclosures Without Devices or Fixtures

An enclosure that does not contain a device(s), other than splicing devices, or support a luminaire, lampholder or other equipment, and that is supported by entering raceways shall not exceed 100 cubic inches (1640 cm3) in size. The enclosure shall have threaded entries or identified hubs. The enclosure shall be supported by two or more conduits threaded wrenchtight into the enclosure or hubs. Each conduit shall be secured within 3 feet (914 mm) of the enclosure, or within 18 inches (457 mm) of the enclosure if all entries are on the same side of the enclosure. [314.23(E)]
Exception: Rigid metal, intermediate metal, or rigid polyvinyl chloride nonmetallic conduit or electrical metallic tubing shall be permitted to support a conduit body of any size, provided that the conduit body is not larger in trade size than the largest trade size of the supporting conduit or electrical metallic tubing. [314.23(E) Exception]

E3906.8.5 Raceway Supported Enclosures, With Devices or Luminaire

An enclosure that contains a device(s), other than splicing devices, or supports a luminaire, lampholder or other equipment and is supported by entering raceways shall not exceed 100 cubic inches (1640 cm3) in size. The enclosure shall have threaded entries or identified hubs. The enclosure shall be supported by two or more conduits threaded wrench-tight into the enclosure or hubs. Each conduit shall be secured within 18 inches (457 mm) of the enclosure. [314.23(F)]
Exceptions:
  1. Rigid metal or intermediate metal conduit shall be permitted to support a conduit body of any size, provided that the conduit bodies are not larger in trade size than the largest trade size of the supporting conduit. [314.23(F) Exception No. 1]
  2. An unbroken length(s) of rigid or intermediate metal conduit shall be permitted to support a box used for luminaire or lampholder support, or to support a wiring enclosure that is an integral part of a luminaire and used in lieu of a box in accordance with Section E3905.1.1, where all of the following conditions are met:
    1. The conduit is securely fastened at a point so that the length of conduit beyond the last point of conduit support does not exceed 3 feet (914 mm).
    2. The unbroken conduit length before the last point of conduit support is 12 inches (305 mm) or greater, and that portion of the conduit is securely fastened at some point not less than 12 inches (305 mm) from its last point of support.
    3. Where accessible to unqualified persons, the luminaire or lampholder, measured to its lowest point, is not less than 8 feet (2438 mm) above grade or standing area and at least 3 feet (914 mm) measured horizontally to the 8-foot (2438 mm) elevation from windows, doors, porches, fire escapes, or similar locations.
    4. A luminaire supported by a single conduit does not exceed 12 inches (305 mm) in any direction from the point of conduit entry.
    5. The weight supported by any single conduit does not exceed 20 pounds (9.1 kg).
    6. At the luminaire or lampholder end, the conduit(s) is threaded wrenchtight into the box, conduit body, or integral wiring enclosure, or into hubs identified for the purpose. Where a box or conduit body is used for support, the luminaire shall be secured directly to the box or conduit body, or through a threaded conduit nipple not over 3 inches (76 mm) long. [314.23(F) Exception No. 2]

E3906.8.6 Enclosures in Concrete or Masonry

An enclosure supported by embedment shall be identified as being suitably protected from corrosion and shall be securely embedded in concrete or masonry. [314.23(G)]

E3906.9 Covers and Canopies

In completed installations, each box shall have a cover, faceplate, lampholder or luminaire canopy.
Screws used for the purpose of attaching covers or other equipment to the box shall be either machine screws matching the thread gauge or size that is integral to the box or shall be in accordance with the manufacturer's instructions. (314.25)

E3906.10 Covers and Plates

Covers and plates shall be nonmetallic or metal. Metal covers and plates shall be grounded. [314.25(A)]

E3906.11 Exposed Combustible Finish

Combustible wall or ceiling finish exposed between the edge of a fixture canopy or pan and the outlet box shall be covered with noncombustible material where required by Section E4004.2. [314.25(B)]

Section E3907 Cabinets and Panelboards

E3907.1 Space Within Switch and Overcurrent Device Enclosures

The wiring space within enclosures for switches and overcurrent devices shall be permitted for other wiring and equipment in accordance with Sections E3907.1.1 and E3907.1.2. [312.8]

E3907.1.1 Splices, Taps and Feed-Through Conductors

Where the wiring space of enclosures for switches or overcurrent device contains conductors feeding through, spliced, or tapping off to other enclosures, switches, or overcurrent devices, the following conditions shall be met:
  1. The total area of all conductors installed at any cross section of the wiring space shall not exceed 40 percent of the cross-sectional area of that space.
  2. The total area of all conductors, splices and taps installed at any cross section of the wiring space shall not exceed 75 percent of the cross-sectional area of that space.
  3. A warning label shall be applied to the enclosure that identifies the closest disconnecting means for any feed-through conductors. [312.8(A)]

E3907.1.2 Power Monitoring or Energy Management Equipment

Where the wiring space of enclosures for switches or overcurrent devices contains power monitoring or energy management equipment, all of the following conditions shall be met:
  1. The power monitoring or energy management equipment shall be identified as a field installable accessory as part of the listed equipment, or shall be a listed kit evaluated for field installation in switch or overcurrent device enclosures.
  2. The total area of all conductors, splices, taps and equipment at any cross section of the wiring space shall not exceed 75 percent of the cross-sectional area of that space.
  3. Conductors used exclusively for control or instrumentation circuits shall comply with one of the following:
    1. Conductors are installed as Class 1 circuits in accordance with Section 725.49 of NFPA 70.
    2. Conductors smaller than 18 AWG, but not smaller than 22 AWG for a single conductor or 26 AWG for a multiconductor cable, shall be permitted to be used where the conductors and cable assemblies meet all of the following conditions:
      1. Are enclosed within raceways or routed along one or more walls of the enclosure and secured at intervals that do not exceed 10 inches (250 mm).
      2. Are secured within 10 inches (250 mm) of terminations.
      3. Are secured to prevent contact with current-carrying components within the enclosure.
      4. Are rated for the system voltage and not less than 600 volts.
      5. Have a minimum insulation temperature rating of 194°F (90°C).

E3907.2 Damp and Wet Locations

In damp or wet locations, cabinets and panelboards of the surface type shall be placed or equipped so as to prevent moisture or water from entering and accumulating within the cabinet, and shall be mounted to provide an airspace not less than 1/4 inch (6.4 mm) between the enclosure and the wall or other supporting surface. Cabinets installed in wet locations shall be weatherproof. For enclosures in wet locations, raceways and cables entering above the level of uninsulated live parts shall be installed with fittings listed for wet locations. (312.2)
Exception: Nonmetallic enclosures installed on concrete, masonry, tile, or similar surfaces shall not be required to be installed with an airspace between the enclosure and the wall or supporting surface. (312.2 Exception)

E3907.3 Position in Wall

In walls of concrete, tile or other noncombustible material, cabinets and panelboards shall be installed so that the front edge of the cabinet will not set back of the finished surface more than 1/4 inch (6.4 mm). In walls constructed of wood or other combustible material, cabinets shall be flush with the finished surface or shall project therefrom. (312.3)

E3907.4 Repairing Noncombustible Surfaces

Noncombustible surfaces that are broken or incomplete shall be repaired so that there will not be gaps or open spaces greater than 1/8 inch (3.2 mm) at the edge of the cabinet or cutout box employing a flush-type cover. (312.4)

E3907.5 Unused Openings

Unused openings, other than those intended for the operation of equipment, those intended for mounting purposes, and those permitted as part of the design for listed equipment, shall be closed to afford protection substantially equivalent to that of the wall of the equipment. Metal plugs and plates used with nonmetallic cabinets shall be recessed at least 1/4 inch (6.4 mm) from the outer surface. Unused openings for circuit breakers and switches shall be closed using identified closures, or other approved means that provide protection substantially equivalent to the wall of the enclosure. (110.12(A)]

E3907.6 Conductors Entering Cabinets

Conductors entering cabinets and panelboards shall be protected from abrasion and shall comply with Section E3906.1.1. (312.5)

E3907.7 Openings to Be Closed

Openings through which conductors enter cabinets, panelboards and meter sockets shall be closed in an approved manner. [312.5(A)]

E3907.8 Cables

Where cables are used, each cable shall be secured to the cabinet, panelboard, cutout box or meter socket enclosure. [312.5(C)]

Exception: Cables with entirely nonmetallic sheaths shall be permitted to enter the top of a surface-mounted enclosure through one or more sections of rigid raceway not less than 18 inches (457 mm) nor more than 10 feet (3048 mm) in length, provided all the following conditions are met:
  1. Each cable is fastened within 12 inches (305 mm), measured along the sheath, of the outer end of the raceway.
  2. The raceway extends directly above the enclosure and does not penetrate a structural ceiling.
  3. A fitting is provided on each end of the raceway to protect the cable(s) from abrasion and the fittings remain accessible after installation.
  4. The raceway is sealed or plugged at the outer end using approved means so as to prevent access to the enclosure through the raceway.
  5. The cable sheath is continuous through the raceway and extends into the enclosure beyond the fitting not less than 1/4 inch (6.4 mm).
  6. The raceway is fastened at its outer end and at other points in accordance with Section E3802.1.
  7. The allowable cable fill for conduit or tubing shall not exceed that permitted by Table E3907.8 and shall be considered as a complete conduit or tubing system. A multiconductor cable having two or more conductors shall be treated as a single conductor for calculating the percentage of conduit fill area. For cables that have elliptical cross sections, the cross-sectional area calculation shall be based on the major diameter of the ellipse as a circle diameter. [312.5(C) Exception]
TABLE E3907.8 (Chapter 9, Table 1)
PERCENT OF CROSS SECTION OF CONDUIT AND TUBING FOR CONDUCTORS
NUMBER OF CONDUCTORS MAXIMUM PERCENT OF CONDUIT AND TUBING AREA FILLED BY CONDUCTORS
1
 53
2
 31
Over 2
 40

E3907.9 Wire-Bending Space Within an Enclosure Containing a Panelboard

Wire-bending space within an enclosure containing a panelboard shall comply with the requirements of Sections E3907.9.1 through E3907.9.3.

E3907.9.1 Top and Bottom Wire-Bending Space

The top and bottom wire-bending space for a panelboard enclosure shall be sized in accordance with Table E3907.9.1(1) based on the largest conductor entering or leaving the enclosure. [408.55 (A)]

Exceptions:
  1. For a panelboard rated at 225 amperes or less and designed to contain not more than 42 overcurrent devices, either the top or bottom wire-bending space shall be permitted to be sized in accordance with Table E3907.9.1(2). For the purposes of this exception, a 2-pole or a 3-pole circuit breaker shall be considered as two or three overcurrent devices, respectively. [408.55(A) Exception No. 1]
  2. For any panelboard, either the top or bottom wire-bending space shall be permitted to be sized in accordance with Table E3907.9.1(2) where the wire-bending space on at least one side is sized in accordance with Table E3907.9.1(1) based on the largest conductor to be terminated in any side wire-bending space. [408.55(A) Exception No. 2]
  3. Where the panelboard is designed and constructed for wiring using only a single 90-degree bend for each conductor, including the grounded circuit conductor, and the wiring diagram indicates and specifies the method of wiring that must be used, the top and bottom wire-bending space shall be permitted to be sized in accordance with Table E3907.9.1(2). [408.55(A) Exception No. 3]
  4. Where there are no conductors terminated in that space, either the top or the bottom wire-bending space, shall be permitted to be sized in accordance with Table E3907.9.1(2). [408.55(A) Exception No. 4]
TABLE E3907.9.1(1) [Table 312.6(B)]
MINIMUM WIRE-BENDING SPACE AT TERMINALS (see Note 1)
WIRE SIZE (AWG or kcmil) WIRES PER TERMINAL
All other conductors Compact stranded AA-8000 aluminum alloy conductors
(see Note 3)		 One (see Note 2) Two
inches mm inches mm
14-10 12-8 Not specified Not specified — —
8 6 11/2 38.1 — —
6 4 2 50.8 — —
4 2 3 76.2 — —
3 1 3 76.2 — —
2 1/0 31/2 88.9 — —
1 2/0 41/2 114 — —
1/0 3/0 51/2 140 51/2 140
2/0 4/0 6 152 6 152
3/0 250 61/2a 165a 61/2a 165a
4/0 300 7b 178b 71/2c 190c
250 350 81/2d 216d 81/2d 229d
300 400 10e 254e 10d 254d
350 500 12e 305e 12c 305c
400 600 13e 330e 13c 330c
500 700-750 14e 356e 14c 356c
600 800-900 15e 381e 16c 406c
700 1,000 16e 406e 18c 457c
Notes:
  1. Bending space at terminals shall be measured in a straight line from the end of the lug or wire connector in a direction perpendicular to the enclosure wall.
  2. For removable and lay-in wire terminals intended for only one wire, bending space shall be permitted to be reduced by the following number of inches (millimeters):
    1. 1/2inch (12.7 mm)
    2. 1 inch (25.4 mm)
    3. 11/2 inches (38.1 mm)
    4. 2 inches (50.8 mm)
    5. 3 inches (76.2 mm)
  3. This column shall be permitted to determine the required wire-bending space for compact stranded aluminum conductors in sizes up to 1,000 kcmil and manufactured using AA-8000 series electrical grade aluminum alloy conductor material.
TABLE E3907.9.1(2) [Table 312.6(A)]
MINIMUM WIRE-BENDING SPACE AT TERMINALS AND MINIMUM WIDTH OF WIRING GUTTERS (see Note 1)
ALL OTHER CONDUCTORS COMPACT STRANDED AA-8000 ALUMINUM ALLOY CONDUCTORS
(see Note 2)		 WIRES PER TERMINAL
One Two
inches mm inches mm
14-10 12-8 Not specified Not specified — —
8-6 6-4 11/2 38.1 — —
4-3 2-1 2 50.8 — —
2 1/0 21/2 63.5 — —
1 2/0 3 76.2 — —
1/0-2/0 3/0-4/0 31/2 88.9 5 127
3/0-4/0 250-300 4 102 6 152
250 350 41/2 114 6 152
300-350 400-500 5 127 8 203
400-500 600-750 6 152 8 203
600-700 800-1000 8 203 10 254
750-900 — 8 203 12 305
1000-1250 — 10 254 — —
1500-2000 — 12 305 — —
Notes:
  1. Bending space at terminals shall be measured in a straight line from the end of the lug or wire connector (in the direction that the wire leaves the terminal) to the wall, barrier, or obstruction.
  2. This column shall be permitted to be used to determine the minimum wire-bending space for compact stranded aluminum conductors in sizes up to 1000 kcmil and manufactured using AA-8000 series electrical grade aluminum alloy conductor material in accordance with 310.106(B). The minimum width of the wire gutter space shall be determined using the all other conductors value in this table.

E3907.9.2 Side Wire-Bending Space

Side wire-bending space shall be in accordance with Table E3907.9.1(2) based on the largest conductor to be terminated in that space. [408.55(B)]

E3907.9.3 Back Wire-Bending Space

The distance between the center of the rear entry and the nearest termination for the entering conductors shall be not less than the distance given in Table E3907.9.1(1). Where a raceway or cable entry is in the wall of the enclosure, opposite a removable cover, the distance from that wall to the cover shall be permitted to comply with the distance required in Table E3907.9.1(2). [408.55 (C)]

Section E3908 Grounding and Bonding

E3908.1 Metal Enclosures

Metal enclosures of conductors, devices and equipment shall be connected to the equipment grounding conductor. (250.86)

Exceptions:
  1. Short sections of metal enclosures or raceways used to provide cable assemblies with support or protection against physical damage. (250.86 Exception No. 2)
  2. Metal components that are installed in an underground installation of rigid nonmetallic conduit and are isolated from possible contact by a minimum cover of 18 inches (457 mm) to any part of the metal components or that are isolated from possible contact by encasement in not less than 2 inches (51 mm) of concrete. (250.86 Exception No. 3)

E3908.2 Equipment Fastened in Place or Connected by Permanent Wiring Methods (Fixed)

Exposed, normally noncurrent-carrying metal parts of fixed equipment supplied by or enclosing conductors or components that are likely to become energized shall be connected to the equipment grounding conductor where any of the following conditions apply:
  1. Where within 8 feet (2438 mm) vertically or 5 feet (1524 mm) horizontally of earth or grounded metal objects and subject to contact by persons;
  2. Where located in a wet or damp location and not isolated; or
  3. Where in electrical contact with metal. (250.110)

E3908.3 Specific Equipment Fastened in Place (Fixed) or Connected by Permanent Wiring Methods

Exposed, normally noncurrent-carrying metal parts of the following equipment and enclosures shall be connected to an equipment grounding conductor:
  1. Luminaires as provided in Chapter 40. [250.112(J)]
  2. Motor-operated water pumps, including submersible types. Where a submersible pump is used in a metal well casing, the well casing shall be connected to the pump circuit equipment grounding conductor. [250.112(L) & (M)]

E3908.4 Effective Ground-Fault Current Path

Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a low-impedance circuit facilitating the operation of the overcurrent device or ground detector for high-impedance grounded systems. Such circuit shall be capable of safely carrying the maximum ground-fault current likely to be imposed on it from any point on the wiring system where a ground fault might occur to the electrical supply source. [250.(A)(5)]

E3908.5 Earth as a Ground-Fault Current Path

The earth shall not be considered as an effective ground-fault current path. [250.4(A)(5)]

E3908.6 Line-Side Grounded (Neutral) Conductor

A grounded circuit conductor shall be permitted to be connected to noncurrent-carrying metal parts of equipment, raceways, and other enclosures at any of the following locations:
  1. On the supply side or within the enclosure of the ac service disconnecting means.
  2. On the supply side or within the enclosure of the main disconnecting means for separate buildings as provided in Section E3607.3.2. [250.142 (A) (1) & (2)]

E3908.7 Load-Side Grounded (Neutral) Conductor

A grounded conductor shall not be connected to normally noncurrent-carrying metal parts of equipment, to equipment grounding conductor(s), or be reconnected to ground on the load side of the service disconnecting means. [250.24(A)(5)]

E3908.8 Load-Side Equipment

A grounded circuit conductor shall not be used for grounding noncurrent-carrying metal parts of equipment on the load side of the service disconnecting means. [250.142(B)]

E3908.9 Types of Equipment Grounding Conductors

The equipment grounding conductor run with or enclosing the circuit conductors shall be one or more or a combination of the following:
  1. A copper, aluminum or copper-clad aluminum conductor. This conductor shall be solid or stranded; insulated, covered or bare; and in the form of a wire or a busbar of any shape. [250.118(1)]
  2. Rigid metal conduit. [250.118(2)]
  3. Intermediate metal conduit. [250.118(3)]
  4. Electrical metallic tubing. [250.118(4)]
  5. Armor of Type AC cable in accordance with Section E3908.4. [250.118(8)]
  6. Type MC cable that provides an effective ground-fault current path in accordance with one or more of the following:
    1. It contains an insulated or uninsulated equipment grounding conductor in compliance with Item 1 of this section.
    2. The combined metallic sheath and uninsulated equipment grounding/bonding conductor of interlocked metal tape-type MC cable that is listed and identified as an equipment grounding conductor.
    3. The metallic sheath or the combined metallic sheath and equipment grounding conductors of the smooth or corrugated tube-type MC cable that is listed and identified as an equipment grounding conductor. [250.118(10)]
  7. Other electrically continuous metal raceways and auxiliary gutters. [250.118(13)]
  8. Surface metal raceways listed for grounding. [250.118(14)]

E3908.9.1 Flexible Metal Conduit

Flexible metal conduit shall be permitted as an equipment grounding conductor where all of the following conditions are met:
  1. The conduit is terminated in listed fittings.
  2. The circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.
  3. The size of the conduit does not exceed trade size 11/4.
  4. The combined length of flexible metal conduit and flexible metallic tubing and liquid-tight flexible metal conduit in the same ground return path does not exceed 6 feet (1829 mm).
If used to connect equipment where flexibility is necessary to minimize the transmission of vibration from equipment or to provide flexibility for equipment that requires movement after installation, an equipment grounding conductor shall be installed. [250.118(5)]

E3908.9.2 Liquid-Tight Flexible Metal Conduit

Liquid-tight flexible metal conduit shall be permitted as an equipment grounding conductor where all of the following conditions are met:
  1. The conduit is terminated in listed fittings.
  2. For trade sizes 3/8 through 1/2 (metric designator 12 through 16), the circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.
  3. For trade sizes 3/4 through 11/4 (metric designator 21 through 35), the circuit conductors contained in the conduit are protected by overcurrent devices rated at not more than 60 amperes and there is no flexible metal conduit, flexible metallic tubing, or liquid-tight flexible metal conduit in trade sizes 3/8 inch or 1/2 inch (9.5 mm through 12.7 mm) in the ground fault current path.
  4. The combined length of flexible metal conduit and flexible metallic tubing and liquid-tight flexible metal conduit in the same ground return path does not exceed 6 feet (1829 mm).
If used to connect equipment where flexibility is necessary to minimize the transmission of vibration from equipment or to provide flexibility for equipment that requires movement after installation, an equipment grounding conductor shall be installed. [250.118(6)]

E3908.9.3 Nonmetallic Sheathed Cable (Type NM)

In addition to the insulated conductors, the cable shall have an insulated, covered, or bare equipment grounding conductor. Equipment grounding conductors shall be sized in accordance with Table E3908.13. (334.108)

E3908.10 Equipment Fastened in Place or Connected by Permanent Wiring Methods

Noncurrent-carrying metal parts of equipment, raceways and other enclosures, where required to be grounded, shall be grounded by one of the following methods: (250.134)
  1. By any of the equipment grounding conductors permitted by Sections E3908.9 through E3908.9.3. [250.134(A)]
  2. By an equipment grounding conductor contained within the same raceway, cable or cord, or otherwise run with the circuit conductors. Equipment grounding conductors shall be identified in accordance with Section E3407.2. [250.134(B)]

E3908.11 Methods of Equipment Grounding

Fixtures and equipment shall be considered grounded where mechanically connected to an equipment grounding conductor as specified in Sections E3908.9 through E3908.9.3. Wire type equipment grounding conductors shall be sized in accordance with Section E3908.13. (250 Part VII)

E3908.12 Equipment Grounding Conductor Installation

Where an equipment grounding conductor consists of a raceway, cable armor or cable sheath or where such conductor is a wire within a raceway or cable, it shall be installed in accordance with the provisions of this chapter and Chapters 34 and 38 using fittings for joints and terminations approved for installation with the type of raceway or cable used. All connections, joints and fittings shall be made tight using suitable tools. [250.120(A)]

E3908.12.1 Aluminum and Copper-Clad Aluminum Equipment Grounding Conductors

Equipment grounding conductors of bare, covered, or insulated aluminum or copper-clad aluminum shall comply with the following:
  1. Unless part of a suitable Chapter 38 cable wiring method, bare or covered conductors shall not be installed where subject to corrosive conditions or be installed in direct contact with concrete, masonry or the earth.
  2. Terminations made within outdoor enclosures that are listed and identified for the environment shall be permitted within 18 inches (457 mm) of the bottom of the enclosure.
  3. Aluminum or copper-clad aluminum conductors external to buildings or enclosures shall not be terminated within 18 inches (457 mm) of the earth, unless terminated within a listed wire connector system. [250.120(B)]

E3908.13 Equipment Grounding Conductor Size

Copper, aluminum and copper-clad aluminum equipment grounding conductors of the wire type shall be not smaller than shown in Table E3908.13, but they shall not be required to be larger than the circuit conductors supplying the equipment. Where a raceway or a cable armor or sheath is used as the equipment grounding conductor, as provided in Section E3908.9, it shall comply with Section E3908.4. Where ungrounded conductors are increased in size for any reason other than as required in Section E3705.2 or E3705.3, wire-type equipment grounding conductors shall be increased in size proportionally according to the circular mil area of the ungrounded conductors. [250.122(A) and (B)]
TABLE E3908.13 (Table 250.122)
EQUIPMENT GROUNDING CONDUCTOR SIZING
RATING OR SETTING OF AUTOMATIC OVERCURRENT DEVICE IN CIRCUIT AHEAD OF EQUIPMENT, CONDUIT, ETC., NOT EXCEEDING THE FOLLOWING RATINGS (amperes) MINIMUM SIZE
Copper wire No. (AWG) Aluminum or copper-clad aluminum wire No. (AWG)
15 14 12
20 12 10
60 10 8
100 8 6
200 6 4
300 4 2
400 3 1

E3908.13.1 Multiple Circuits

A single equipment grounding conductor shall be permitted to be installed for multiple circuits that are installed in the same raceway, cable or trench. It shall be sized in accordance with Table E3908.13 for the largest overcurrent device protecting circuit conductors in the raceway, cable or trench. [250.122(C)]

E3908.14 Continuity of Equipment Grounding Conductors and Attachment to Boxes

Where circuit conductors are spliced within a box or terminated on equipment within or supported by a box, all wire-type equipment grounding conductors associated with any of those circuit conductors shall be connected within the box or to the box with devices suitable for the use in accordance with Section E3406.13.1. Connections depending solely on solder shall not be used. Splices shall be made in accordance with Section E3406.10 except that insulation shall not be required. The arrangement of grounding connections shall be such that the disconnection or removal of a receptacle, luminaire or other device fed from the box will not interfere with or interrupt the grounding continuity. [250.8(B), 250.148(A) and (B)]

E3908.15 Connecting Receptacle Grounding Terminal to an Equipment Grounding Conductor

An equipment bonding jumper, sized in accordance with Table E3908.13 based on the rating of the overcurrent device protecting the circuit conductors, shall be used to connect the grounding terminal of a grounding-type receptacle to a metal box that is connected to an equipment grounding conductor except as permitted by of the following: (250.146)
  1. Surface-mounted box. Where a metal box is mounted on the surface, the direct metal-to-metal contact between the device yoke or strap to the box shall be permitted to provide the required effective ground fault current path. At least one of the insulating washers shall be removed from receptacles that do not have a contact yoke or device to ensure direct metal-to-metal contact. Direct metal-to-metal contact for providing continuity applies to cover-mounted receptacles where the box and cover combination are listed as providing satisfactory continuity between the box and the receptacle. A listed exposed work cover shall be considered to be the grounding and bonding means where the device is attached to the cover with at least two fasteners that are permanent, such as a rivet or have a thread locking or screw locking means and where the cover mounting holes are located on a flat non-raised portion of the cover. [250.146(A)]
  2. Contact devices or yokes. Contact devices or yokes designed and listed for the purpose shall be permitted in conjunction with the supporting screws to establish equipment bonding between the device yoke and flush-type boxes. [250.146(B)]
  3. Floor boxes. Floor boxes designed for and listed as providing satisfactory continuity between the box and the device shall be permitted. [250.146(C)]

E3908.16 Metal Boxes

A connection used for no other purpose shall be made between the metal box and the equipment grounding conductor(s) in accordance with Section E3406.14.1. [250.148(C)]

E3908.17 Nonmetallic Boxes

One or more equipment grounding conductors brought into a nonmetallic outlet box shall be arranged to allow connection of any fittings or devices installed in that box to an equipment grounding conductor. [250.148(D)]

E3908.18 Clean Surfaces

Nonconductive coatings such as paint, lacquer and enamel on equipment to be grounded or bonded shall be removed from threads and other contact surfaces to ensure good electrical continuity or the equipment shall be connected by means of fittings designed so as to make such removal unnecessary. (250.12)

E3908.19 Bonding Other Enclosures

Metal raceways, cable armor, cable sheath, enclosures, frames, fittings and other metal noncurrent-carrying parts that serve as equipment grounding conductors, with or without the use of supplementary equipment grounding conductors, shall be effectively bonded where necessary to ensure electrical continuity and the capacity to conduct safely any fault current likely to be imposed on them. Any nonconductive paint, enamel and similar coating shall be removed at threads, contact points and contact surfaces, or connections shall be made by means of fittings designed so as to make such removal unnecessary. [250.96(A)]

E3908.20 Size of Equipment Bonding Jumper on Load Side of an Overcurrent Device

The equipment bonding jumper on the load side of an overcurrent devices shall be sized, as a minimum, in accordance with Table E3908.13, but shall not be required to be larger than the circuit conductors supplying the equipment. An equipment bonding conductor shall be not smaller than No. 14 AWG.
A single common continuous equipment bonding jumper shall be permitted to connect two or more raceways or cables where the bonding jumper is sized in accordance with Table E3908.13 for the largest overcurrent device supplying circuits therein. [250.102(D) and 250.122]

E3908.21 Installation Equipment Bonding Jumper

Bonding jumpers or conductors and equipment bonding jumpers shall be installed either inside or outside of a raceway or an enclosure in accordance with Sections E3908.21.1 and E3908.21.2. [250.102(E)]

E3908.21.1 Inside Raceway or Enclosure

Where installed inside a raceway or enclosure, equipment bonding jumpers and bonding jumpers or conductors shall comply with the requirements of Sections E3407.2 and E3908.14. [250.102(E)(1)]

E3908.21.2 Outside a Raceway or an Enclosure

Where installed outside of a raceway or enclosure, the length of the bonding jumper or conductor or equipment bonding jumper shall not exceed 6 feet (1829 mm) and shall be routed with the raceway or enclosure. [250.102(E)(2)]
Equipment bonding jumpers and supply-side bonding jumpers installed for bonding grounding electrodes and installed at outdoor pole locations for the purpose of bonding or grounding isolated sections of metal raceways or elbows installed in exposed risers of metal conduit or other metal raceway, shall not be limited in length and shall not be required to be routed with a raceway or enclosure. [250.102(E)(2) Exception]

E3908.21.3 Protection

Bonding jumpers or conductors and equipment bonding jumpers shall be installed in accordance with Section E3610.2. [250.102(E)(3)]

Section E3909 Flexible Cords and Flexible Cables

E3909.1 Where Permitted

Flexible cords and flexible cables shall be used only for the connection of appliances where the fastening means and mechanical connections of such appliances are designed to permit ready removal for maintenance, repair or frequent interchange and the appliance is listed for flexible cord connection. Flexible cords, flexible cables, cord sets and power supply cords shall not be installed as a substitute for the fixed wiring of a structure; shall not be run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings or floors; shall not be concealed behind walls, floors, ceilings or located above suspended or dropped ceilings; and shall not be attached to building surfaces. (400.10 and 400.12)

E3909.2 Loading and Protection

The ampere load of flexible cords serving fixed appliances shall be in accordance with Table E3909.2. This table shall be used in conjunction with applicable end use product standards to ensure selection of the proper size and type. Where flexible cord is approved for and used with a specific listed appliance, it shall be considered to be protected where applied within the appliance listing requirements. [240.4, 240.5(A), 240.5(B)(1), 400.5, and 400.16]

TABLE E3909.2 [Table 400.5(A)(1)]
MAXIMUM AMPERE LOAD FOR FLEXIBLE CORDS
CORD SIZE (AWG) CORD TYPES S, SE, SEO, SJ, SJE, SJEO, SJO, SJOO, SJT, SJTO, SJTOO, SO, SOO, SRD, SRDE, SRDT, ST, STD, SV, SVO, SVOO, SVTO, SVTOO
Maximum ampere load
Three current-carrying conductors Two current-carrying conductors
18 7 10
16
10
13
14
15
18
12
20
25

E3909.3 Splices

Flexible cord shall be used only in continuous lengths without splices or taps. (400.13)

E3909.4 Attachment Plugs

Where used in accordance with Section E3909.1, each flexible cord shall be equipped with an attachment plug and shall be energized from a receptacle outlet. [400.10(B)]