Heads up: There are no amended sections in this chapter.
Part I General
This article covers the installation of conductors, equipment, and field wiring for electric signs, retrofit kits, and outline lighting, regardless of voltage. All installations and equipment using neon tubing, such as signs, decorative elements, skeleton tubing, or art forms, are covered by this article.
LED Sign Illumination System. A complete lighting system for use in signs and outline lighting consisting of light-emitting diode (LED) light sources, power supplies, wire, and connectors to complete the installation.
Neon Tubing. Electric-discharge luminous tubing, including cold cathode luminous tubing, that is manufactured into shapes to illuminate signs, form letters, parts of letters, skeleton tubing, outline lighting, other decorative elements, or art forms and filled with various inert gases.
Photovoltaic (PV) Powered Sign. A complete sign powered by solar energy consisting of all components and subassemblies for installation either as an off-grid stand-alone, on-grid interactive, or non-grid interactive system.
Section Sign. A sign or outline lighting system, shipped as subassemblies, that requires field-installed wiring between the subassemblies to complete the overall sign. The subassemblies are either physically joined to form a single sign unit or are installed as separate remote parts of an overall sign.
Sign Body. A portion of a sign that may provide protection from the weather but is not an electrical enclosure.
Fixed, mobile, or portable electric signs, section signs, outline lighting, photovoltaic (PV) powered signs, and retrofit kits, regardless of voltage, shall be listed, provided with installation instructions, and installed in conformance with that listing, unless otherwise approved by special permission.
Field-installed skeleton tubing shall not be required to be listed where installed in conformance with this Code.
- The retrofitted sign shall be marked that the illumination system has been replaced.
- The marking shall include the kit providers and installer's name, logo, or unique identifier.
- Signs equipped with tubular light-emitting diode lamps powered by the existing sign sockets shall include a label alerting the service personnel that the sign has been modified. The label shall meet the requirements of 110.21(B). The label shall also include a warning not to install fluorescent lamps and shall also be visible during relamping.
Signs and outline lighting systems with lampholders for incandescent lamps shall be marked to indicate the maximum allowable lamp wattage per lampholder. The markings shall be permanently installed, in letters at least 6 mm (1/4 in.) high, and shall be located where visible during relamping.
Each commercial building and each commercial occupancy accessible to pedestrians shall be provided with at least one outlet in an accessible location at each entrance to each tenant space for sign or outline lighting system use. The outlet(s) shall be supplied by a branch circuit rated at least 20 amperes that supplies no other load. Service hallways or corridors shall not be considered accessible to pedestrians.
Wiring methods used to supply signs shall comply with 600.5(C)(1), (C)(2), and (C)(3).
Metal or nonmetallic poles used to support signs shall be permitted to enclose supply conductors, provided the poles and conductors are installed in accordance with 410.30(B).
Each sign and outline lighting system, feeder conductor(s), or branch circuit(s) supplying a sign, outline lighting system, or skeleton tubing shall be controlled by an externally operable switch or circuit breaker that opens all ungrounded conductors and controls no other load. The switch or circuit breaker shall open all ungrounded conductors simultaneously on multi-wire branch circuits in accordance with 210.4(B). Signs and outline lighting systems located within fountains shall have the disconnect located in accordance with 680.13.
Exception No. 1: A disconnecting means shall not be required for an exit directional sign located within a building.
Exception No. 2: A disconnecting means shall not be required for cord-connected signs with an attachment plug.
The disconnect shall be located at the point the feeder circuit or branch circuit(s) supplying a sign or outline lighting system enters a sign enclosure, a sign body, or a pole in accordance with 600.5(C)(3). The disconnect shall open all ungrounded conductors where it enters the enclosure of the sign or pole.
Exception No. 1: A disconnect shall not be required for branch circuit(s) or feeder conductor(s) passing through the sign where enclosed in a Chapter 3 listed raceway or metal-jacketed cable identified for the location.
Exception No. 2: A disconnect shall not be required at the point of entry to a sign enclosure or sign body for branch circuit(s) or feeder conductor(s) that supply an internal panelboard(s) in a sign enclosure or sign body. The conductors shall be enclosed in a Chapter 3 listed raceway or metal-jacketed cable identified for the location. A field-applied permanent warning label that is visible during servicing shall be applied to the raceway at or near the point of entry into the sign enclosure or sign body. The warning label shall comply with 110.21(B) and state the following: "Danger. This raceway contains energized conductors." The marking shall include the location of the disconnecting means for the energized conductor(s). The disconnecting means shall be capable of being locked in the open position in accordance with 110.25.
The disconnecting means shall be within sight of the sign or outline lighting system that it controls. Where the disconnecting means is out of the line of sight from any section that is able to be energized, the disconnecting means shall be lockable in accordance with 110.25. A permanent field-applied marking identifying the location of the disconnecting means shall be applied to the sign in a location visible during servicing. The warning label shall comply with 110.21(B).
The following shall apply for signs or outline lighting systems operated by electronic or electromechanical controllers located external to the sign or outline lighting system:
- The disconnecting means shall be located within sight of the controller or in the same enclosure with the controller.
- The disconnecting means shall disconnect the sign or outline lighting system and the controller from all ungrounded supply conductors.
- The disconnecting means shall be designed such that no pole can be operated independently and shall be lockable in accordance with 110.25.
Metal equipment of signs, outline lighting, and skeleton tubing systems shall be grounded by connection to the equipment grounding conductor of the supply branch circuit(s) or feeder using the types of equipment grounding conductors specified in 250.118.
Metal parts of a building shall not be permitted as a secondary return conductor or an equipment grounding conductor.
Metal parts and equipment of signs and outline lighting systems shall be bonded together and to the associated transformer or power-supply equipment grounding conductor of the branch circuit or feeder supplying the sign or outline lighting system and shall meet the requirements of 250.90.
Listed flexible metal conduit or listed liquidtight flexible metal conduit that encloses the secondary circuit conductor from a transformer or power supply for use with neon tubing shall be permitted as a bonding means if the total accumulative length of the conduit in the secondary circuit does not exceed 30 m (100 ft).
Where listed nonmetallic conduit is used to enclose the secondary circuit conductor from a transformer or power supply and a bonding conductor is required, the bonding conductor shall be installed separate and remote from the nonmetallic conduit and be spaced at least 38 mm (11/2 in.) from the conduit when the circuit is operated at 100 Hz or less or 45 mm (13/4 in.) when the circuit is operated at over 100 Hz.
Signs or outline lighting installed inside a fountain shall have all metal parts bonded to the equipment grounding conductor of the branch circuit for the fountain recirculating system. The bonding connection shall be as near as practicable to the fountain and shall be permitted to be made to metal piping systems that are bonded in accordance with 680.53.
Sheet copper or aluminum shall be at least 0.51 mm (0.020 in.) thick. Sheet steel shall be at least 0.41 mm (0.016 in.) thick.
Signs and outline lighting systems shall be installed so that adjacent combustible materials are not subjected to temperatures in excess of 90°C (194°F).
The spacing between wood or other combustible materials and an incandescent or HID lamp or lampholder shall not be less than 50 mm (2 in.).
Signs and outline lighting system equipment for wet location use, other than listed watertight type, shall be weatherproof and have drain holes, as necessary, in accordance with the following:
The manufacturer of portable or mobile signs shall provide listed ground-fault circuit-interrupter protection for personnel. The ground-fault circuit interrupter shall be an integral part of the attachment plug or shall be located in the power-supply cord within 300 mm (12 in.) of the attachment plug.
Neon and secondary circuit wiring of 1000 volts or less shall comply with 600.31.
Where the installation complies with 600.33 and the power source provides a Class 2 output that complies with 600.24, either of the following wiring methods shall be permitted as determined by the installation instructions and conditions.
Ballasts, transformers, electronic power supplies, and Class 2 power sources shall be permitted to be located in attics and soffits, provided there is an access door at least 900 mm × 562.5 mm (36 in. × 221/2 in.) and a passageway of at least 900 mm (3 ft) high × 600 mm (2 ft) wide with a suitable permanent walkway at least 300 mm (12 in.) wide extending from the point of entry to each component. At least one lighting outlet containing a switch or controlled by a wall switch shall be installed in such spaces. At least one point of control shall be at the usual point of entry to these spaces. The lighting outlet shall be provided at or near the equipment requiring servicing.
Ballasts, transformers, electronic power supplies, and Class 2 power sources shall be permitted to be located above suspended ceilings, provided that their enclosures are securely fastened in place and not dependent on the suspended-ceiling grid for support. Ballasts, transformers, and electronic power supplies installed in suspended ceilings shall not be connected to the branch circuit by flexible cord.
Transformers and electronic power supplies other than the following shall have secondary-circuit ground-fault protection:
Transformers and electronic power supplies shall have a secondary-circuit current rating of not more than 300 mA.
Secondary circuit outputs shall not be connected in parallel or in series.
Part II Field-Installed Skeleton Tubing, Outline Lighting, and Secondary Wiring
Conductors shall be installed using any wiring method included in Chapter 3 suitable for the conditions.
Conductors shall be listed, insulated, and not smaller than 18 AWG.
Conductors shall be installed so they are not subject to physical damage.
Bushings shall be used to protect wires passing through an opening in metal.
Conductors shall be installed in rigid metal conduit, intermediate metal conduit, liquidtight flexible nonmetallic conduit, flexible metal conduit, liquidtight flexible metal conduit, electrical metallic tubing, metal enclosures; on insulators in metal raceways; or in other equipment listed for use with neon secondary circuits over 1000 volts.
Conduit or tubing shall contain only one conductor.
Conduit or tubing shall be a minimum of metric designator 16 (trade size 1/2).
Other than at the location of connection to a metal enclosure or sign body, nonmetallic conduit or flexible nonmetallic conduit shall be spaced no less than 38 mm (11/2 in.) from grounded or bonded parts when the conduit contains a conductor operating at 100 Hz or less, and shall be spaced no less than 45 mm (13/4 in.) from grounded or bonded parts when the conduit contains a conductor operating at more than 100 Hz.
Metal parts of a building shall not be permitted as a secondary return conductor or an equipment grounding conductor.
Conductors shall be insulated, listed as gas tube sign and ignition cable type GTO, rated for 5, 10, or 15 kV, not smaller than 18 AWG, and have a minimum temperature rating of 105°C (221°F).
Conductors shall be so installed that they are not subject to physical damage.
Insulators and bushings for conductors shall be listed for use with neon secondary circuits over 1000 volts.
The insulation on all conductors shall extend not less than 65 mm (21/2 in.) beyond the metal conduit or tubing.
All other sections of secondary circuit conductor in a neon tube circuit shall be as short as practicable.
Class 2 cable listed for the application that complies with Table 600.33(A)(1) or Table 600.33(A)(2) for substitutions shall be installed on the load side of the Class 2 power source. The conductors shall have an ampacity not less than the load to be supplied and shall not be sized smaller than 18 AWG.
|Non-concealed spaces inside buildings||Y||Y||Y||Y||Y||Y||Y|
|Concealed spaces inside buildings that are not used as plenums or risers||Y||Y||Y||Y||Y||Y||Y|
|Environmental air spaces plenums- or risers||N||N||N||N||Y||Y||N|
|Y = Permitted. N = Not Permitted.|
Class 2 Cable Substitutions
Class 2 Cable Substitutions
|Cable Type||Permitted Substitutions|
|CL3R||CMP, CL3P, CMR|
|CL2R||CMP, CL3P, CL2P, CMR, CL3R|
|CL3||CMP, CL3P, CMR, CL3R, CMG, CM, PLTC|
|CL2||CMP, CL3P, CL2P, CMR, CL3R, CL2R, CMG, CM, PLTC, CL3|
|CL3X||CMP, CL3P, CMR, CL3R, CMG, CM, PLTC, CL3, CMX|
|CL2X||CMP, CL3P, CL2P, CMR, CL3R, CL2R, CMG, CM, PLTC, CL3, CL2, CMX, CL3X|
CL2 or CL3, PLTC, or any listed applicable cable for general use shall be installed within and on buildings or structures.
In other locations, any listed applicable cable permitted in 600.33(A)(1), (A)(2), (A)(3), and (A)(4) and Table 600.33(A)(1) and (A)(2) shall be permitted to be used as follows:
- CL2P or CL3P — Ducts, plenums, or other spaces used for environmental air
- CL2R or CL3R — Vertical shafts and risers
- Substitutions from Table 600.33(A)(2)
Secondary wiring shall be installed in accordance with (B)(1) and (B)(2).
- Wiring shall be installed and supported in a neat and workmanlike manner. Cables and conductors installed exposed on the surface of ceilings and sidewalls shall be supported by the building structure in such a manner that the cable is not damaged by normal building use. The cable shall be supported and secured at intervals not exceeding 1.8 m (6 ft). Such cables shall be supported by straps, staples, hangers, cable ties, or similar fittings designed and installed so as not to damage the cable. The installation shall also comply with 300.4(D).
- Connections in cable and conductors shall be made with listed insulating devices and be accessible after installation. Where made in a wall, connections shall be enclosed in a listed box.
Where subject to physical damage, the conductors shall be protected and installed in accordance with 300.4.
Wiring from a photovoltaic panel or wiring external to the PV sign body shall be:
Tubing shall be supported by listed tube supports. The neon tubing shall be supported within 150 mm (6 in.) from the electrode connection.
A spacing of not less than 6 mm (1/4 in.) shall be maintained between the tubing and the nearest surface, other than its support.
Neon secondary conductor(s) shall be supported not more than 150 mm (6 in.) from the electrode connection to the tubing.
Manufactured Wiring System. A system containing component parts that are assembled in the process of manufacture and cannot be inspected at the building site without damage or destruction to the assembly and used for the connection of luminaires, utilization equipment, continuous plug-in type busways, and other devices.
Manufactured wiring systems and associated components shall be listed.
Informational Note: ANSI/UL 183, Standard for Manufacturing Wiring Systems, is a safety standard for manufactured wiring systems.
Manufactured wiring systems shall be permitted in accessible and dry locations and in ducts, plenums, and other air-handling spaces where listed for this application and installed in accordance with 300.22.
Exception No. 1: In concealed spaces, one end of tapped cable shall be permitted to extend into hollow walls for direct termination at switch and outlet points.
Exception No. 2: Manufactured wiring system assemblies installed outdoors shall be listed for use in outdoor locations.
Manufactured wiring system types shall not be permitted where limited by the applicable article in Chapter 3 for the wiring method used in its construction.
Cable shall be one of the following:
- Listed Type AC cable containing nominal 600-volt, 8 to 12 AWG insulated copper conductors with a bare or insulated copper equipment grounding conductor equivalent in size to the ungrounded conductor.
- Listed Type MC cable containing nominal 600-volt, 8 to 12 AWG insulated copper conductors with a bare or insulated copper equipment grounding conductor equivalent in size to the ungrounded conductor.
- Listed Type MC cable containing nominal 600-volt, 8 to 12 AWG insulated copper conductors with a grounding conductor and armor assembly listed and identified for grounding in accordance with 250.118(10). The combined metallic sheath and grounding conductor shall have a current-carrying capacity equivalent to that of the ungrounded copper conductor.
Conduit shall be listed flexible metal conduit or listed liquidtight flexible conduit containing nominal 600-volt, 8 to 12 AWG insulated copper conductors with a bare or insulated copper equipment grounding conductor equivalent in size to the ungrounded conductor.
Exception No. 1 to (1) and (2): A luminaire tap, no longer than 1.8 m (6 ft) and intended for connection to a single luminaire, shall be permitted to contain conductors smaller than 12 AWG but not smaller than 18 AWG.
Exception No. 2 to (1) and (2): Listed manufactured wiring assemblies containing conductors smaller than 12 AWG shall be permitted for remote-control, signaling, or communication circuits.
Exception No. 3 to (2): Listed manufactured wiring systems containing unlisted flexible metal conduit of noncircular cross section or trade sizes smaller than permitted by 348.20(A), or both, shall be permitted where the wiring systems are supplied with fittings and conductors at the time of manufacture.
Flexible cord suitable for hard usage, with minimum 12 AWG conductors, shall be permitted as part of a listed factory-made assembly not exceeding 1.8 m (6 ft) in length when making a transition between components of a manufactured wiring system and utilization equipment not permanently secured to the building structure. The cord shall be visible for the entire length, shall not be subject to physical damage, and shall be provided with identified strain relief.
Busways shall be listed continuous plug-in type containing factory-mounted, bare or insulated conductors, which shall be copper or aluminum bars, rods, or tubes. The busway shall be provided with an equipment ground. The busway shall be rated nominal 600 volts, 20, 30, or 40 amperes. Busways shall be installed in accordance with 368.12, 368.17(D), and 368.30.
Receptacles and connectors shall be of the locking type, uniquely polarized and identified for the purpose, and shall be part of a listed assembly for the appropriate system. All connector openings shall be designed to prevent inadvertent contact with live parts or capped to effectively close the connector openings.
Other component parts shall be listed for the appropriate system.
This article covers electrical equipment, lighting accessories, and wiring systems used to connect, contained within, or installed on office furnishings.
Office Furnishing. Cubicle panels, partitions, study carrels, workstations, desks, shelving systems, and storage units that may be mechanically and electrically interconnected to form an office furnishing system.
Wiring systems shall be identified as suitable for providing power for lighting accessories and utilization equipment used within office furnishings. A wired partition shall not extend from floor to ceiling.
Exception: Where permitted by the authority having jurisdiction, these relocatable wired partitions shall be permitted to extend to, but shall not penetrate, the ceiling.
These assemblies shall be installed and used only as provided for by this article.
All conductors and connections shall be contained within wiring channels of metal or other material identified as suitable for the conditions of use. Wiring channels shall be free of projections or other conditions that might damage conductor insulation.
The electrical connection between office furnishings shall be a flexible assembly identified for use with office furnishings or shall be permitted to be installed using flexible cord, provided that all the following conditions are met:
- The cord is extra-hard usage type with 12 AWG or larger conductors, with an insulated equipment grounding conductor.
- The office furnishings are mechanically contiguous.
- The cord is not longer than necessary for maximum positioning of the office furnishing but is in no case to exceed 600 mm (2 ft).
- The cord is terminated at an attachment plug-and-cord connector with strain relief.
A means for secure attachment or support shall be provided.
Where cord and plug connection is provided, it shall comply with all of the following:
- The cord length shall be suitable for the intended application but shall not exceed 2.7 m (9 ft) in length.
- The cord shall not be smaller than 18 AWG.
- The cord shall contain an equipment grounding conductor, except as specified in 605.6(B)(4).
- Cords on the load side of a listed Class 2 power source shall not be required to contain an equipment grounding conductor.
- The cord shall be of the hard usage type, except as specified in 605.6(B)(6).
- A cord provided on a listed Class 2 power source shall be of the type provided with the listed luminaire assembly or of the type specified in 725.130 and 725.127.
- Connection by other means shall be identified as suitable for the conditions of use.
Individual office furnishings of the freestanding type, or groups of individual office furnishings that are electrically connected, are mechanically contiguous, and do not exceed 9.0 m (30 ft) when assembled, shall be permitted to be connected to the building electrical system by a single flexible cord and plug, provided that all of the conditions of 605.9(A) through (D) are met.
The receptacle(s) supplying power shall be on a separate circuit serving only the office furnishing and no other loads and shall be located not more than 300 mm (12 in.) from the office furnishing that is connected to it.
An individual office furnishing or groups of interconnected individual office furnishings shall not contain more than 13 15-ampere, 125-volt receptacles. For purposes of this requirement, a receptacle is considered (1) up to two (simplex) receptacles provided within a single enclosure and that are within 0.3 m (1 ft) of each other or (2) one duplex receptacle.
Part I General
This article covers the installation of electrical equipment and wiring used in connection with cranes, monorail hoists, hoists, and all runways.
Informational Note: For further information, see ASME B30, Safety Standards for Cableways, Cranes, Derricks, Hoists, Hooks, Jacks, and Slings.
Where a crane, hoist, or monorail hoist operates over readily combustible material, the resistors shall be located as permitted in the following:
Part II Wiring
Where multiconductor cable is used with a suspended pushbutton station, the station shall be supported in some satisfactory manner that protects the electrical conductors against strain.
Where flexibility is required for power or control to moving parts, listed festoon cable or a cord suitable for the purpose shall be permitted, provided the following apply:
A bushing shall be permitted to be used in lieu of a box at the end of a rigid metal conduit, intermediate metal conduit, or electrical metallic tubing where the raceway terminates at unenclosed controls or similar equipment, including contact conductors, collectors, resistors, brakes, power-circuit limit switches, and dc split-frame motors.
Conductors shall comply with Table 310.104(A) unless otherwise permitted in 610.13(A) through (D).
A conductor(s) exposed to external heat or connected to resistors shall have a flame-resistant outer covering or be covered with flame-resistant tape individually or as a group.
The allowable ampacities of conductors shall be as shown in Table 610.14(A).
Table 610.14(A) Ampacities of Insulated Copper Conductors Used with Short-Time Rated Crane and Hoist Motors. Based on Ambient Temperature of 30°C (86°F).
|Maximum Operating Temperature||Up to Four Simultaneously Energized Conductors in Raceway or Cable1||Up to Three ac2 or Four dc1 Simultaneously Energized Conductors in Raceway or Cable||Maximum Operating Temperature|
|75°C (167°F)||90°C (194°F)||125°C (257°F)|
|Size (AWG or kcmil)||Types MTW, RHW, THW, THWN, XHHW, USE, ZW||Types TA, TBS, SA, SIS, PFA, FEP, FEPB, RHH, THHN, XHHW, Z, ZW||Types FEP, FEPB, PFA, PFAH, SA, TFE, Z, ZW||Size (AWG or kcmil)|
|60 Min||30 Min||60 Min||30 Min||60 Min||30 Min|
|AMPACITY CORRECTION FACTORS|
|Ambient Temperature (°C)||For ambient temperatures other than 30°C (86°F), multiply the ampacities shown above by the appropriate factor shown below.||Ambient Temperature (°F)|
|Note: Other insulations shown in Table 310.104(A) and approved for the temperature and location shall be permitted to be substituted for those shown in Table 610.14(A). The allowable ampacities of conductors used with 15-minute motors shall be the 30-minute ratings increased by 12 percent.|
|1 For 5 to 8 simultaneously energized power conductors in raceway or cable, the ampacity of each power conductor shall be reduced to a value of 80 percent of that shown in this table.|
|2 For 4 to 6 simultaneously energized 125°C (257°F) ac power conductors in raceway or cable, the ampacity of each power conductor shall be reduced to a value of 80 percent of that shown in this table.|
Where the secondary resistor is separate from the controller, the minimum size of the conductors between controller and resistor shall be calculated by multiplying the motor secondary current by the appropriate factor from Table 610.14(B) and selecting a wire from Table 610.14(A).
Secondary Conductor Rating Factors
Secondary Conductor Rating Factors
|Time in Seconds||Ampacity of Wire in Percent of Full-Load Secondary Current|
Contact wires shall have an ampacity not less than that required by Table 610.14(A) for 75°C (167°F) wire, and in no case shall they be smaller than as shown in Table 610.14(D).
Minimum Contact Conductor Size Based on Distance Between Supports
Minimum Contact Conductor Size Based on Distance Between Supports
|Minimum Size of Wire (AWG)||Maximum Distance Between End Strain Insulators or Clamp-Type Intermediate Supports|
|6||9.0 m (30 ft) or less|
|4||18 m (60 ft) or less|
|2||Over 18 m (60 ft)|
For one motor, 100 percent of motor nameplate full-load ampere rating shall be used.
For multiple motors on a single crane or hoist, the minimum ampacity of the power supply conductors shall be the nameplate full-load ampere rating of the largest motor or group of motors for any single crane motion, plus 50 percent of the nameplate full-load ampere rating of the next largest motor or group of motors, using that column of Table 610.14(A) that applies to the longest time-rated motor.
Additional loads, such as heating, lighting, and air conditioning, shall be provided for by application of the appropriate sections of this Code.
Each crane, monorail, or hoist shall be provided with a visible nameplate marked with the manufacturer's name, rating in volts, frequency, number of phases, and circuit amperes as calculated in 610.14(E) and (F).
Where a crane or hoist is operated by more than one motor, a common-return conductor of proper ampacity shall be permitted.
Part III Contact Conductors
Contact conductors shall comply with 610.21(A) through (H).
Main contact conductors carried along runways shall be supported on insulating supports placed at intervals not exceeding 6.0 m (20 ft) unless otherwise permitted in 610.21(F).
Such conductors shall be separated at not less than 150 mm (6 in.), other than for monorail hoists where a spacing of not less than 75 mm (3 in.) shall be permitted. Where necessary, intervals between insulating supports shall be permitted to be increased up to 12 m (40 ft), the separation between conductors being increased proportionately.
Bridge wire contact conductors shall be kept at least 65 mm (21/2 in.) apart, and, where the span exceeds 25 m (80 ft), insulating saddles shall be placed at intervals not exceeding 15 m (50 ft).
Conductors along runways and crane bridges, that are of the rigid type specified in 610.13(B) and not contained within an approved enclosed assembly, shall be carried on insulating supports spaced at intervals of not more than 80 times the vertical dimension of the conductor, but in no case greater than 4.5 m (15 ft), and spaced apart sufficiently to give a clear electrical separation of conductors or adjacent collectors of not less than 25 mm (1 in.).
Monorail, tram rail, or crane runway tracks shall be permitted as a conductor of current for one phase of a 3-phase, ac system furnishing power to the carrier, crane, or trolley, provided all of the following conditions are met:
- The conductors supplying the other two phases of the power supply are insulated.
- The power for all phases is obtained from an insulating transformer.
- The voltage does not exceed 300 volts.
- The rail serving as a conductor shall be bonded to the equipment grounding conductor at the transformer and also shall be permitted to be grounded by the fittings used for the suspension or attachment of the rail to a building or structure.
All sections of contact conductors shall be mechanically joined to provide a continuous electrical connection.
Collectors shall be designed so as to reduce to a minimum sparking between them and the contact conductor; and, where operated in rooms used for the storage of easily ignitible combustible fibers and materials, they shall comply with 503.155.
Part IV Disconnecting Means
A disconnecting means that has a continuous ampere rating not less than that calculated in 610.14(E) and (F) shall be provided between the runway contact conductors and the power supply. The disconnecting means shall comply with 430.109. This disconnecting means shall be as follows:
- Readily accessible and operable from the ground or floor level
- Lockable open in accordance with 110.25
- Open all ungrounded conductors simultaneously
- Placed within view of the runway contact conductors
Exception: The runway conductor disconnecting means for electrolytic cell lines shall be permitted to be placed out of view of the runway contact conductors where either of the following conditions are met:
- Where a location in view of the contact conductors is impracticable or introduces additional or increased hazards to persons or property
- In industrial installations, with written safety procedures, where conditions of maintenance and supervision ensure that only qualified persons service the equipment
A disconnecting means in compliance with 430.109 shall be provided in the leads from the runway contact conductors or other power supply on all cranes and monorail hoists. The disconnecting means shall be lockable open in accordance with 110.25.
Where a monorail hoist or hand-propelled crane bridge installation meets all of the following, the disconnecting means shall be permitted to be omitted:
- The unit is controlled from the ground or floor level.
- The unit is within view of the power supply disconnecting means.
- No fixed work platform has been provided for servicing the unit.
Means shall be provided at the operating station to open the power circuit to all motors of the crane or monorail hoist.
Part V Overcurrent Protection
The runway supply conductors and main contact conductors of a crane or monorail shall be protected by an overcurrent device(s) that shall not be greater than the largest rating or setting of any branch-circuit protective device plus the sum of the nameplate ratings of all the other loads with application of the demand factors from Table 610.14(E).
Crane, hoist, and monorail hoist motor branch circuits shall be protected by fuses or inverse-time circuit breakers that have a rating in accordance with Table 430.52. Where two or more motors operate a single motion, the sum of their nameplate current ratings shall be considered as that of a single motor.
Each motor, motor controller, and branch-circuit conductor shall be protected from overload by one of the following means:
- A single motor shall be considered as protected where the branch-circuit overcurrent device meets the rating requirements of 610.42.
- Overload relay elements in each ungrounded circuit conductor, with all relay elements protected from short circuit by the branch-circuit protection.
- Thermal sensing devices, sensitive to motor temperature or to temperature and current, that are thermally in contact with the motor winding(s). Hoist functions shall be considered to be protected if the sensing device limits the hoist to lowering only during an overload condition. Traverse functions shall be considered to be protected if the sensing device limits the travel in both directions for the affected function during an overload condition of either motor.
Where two or more motors drive a single trolley, truck, or bridge and are controlled as a unit and protected by a single set of overload devices with a rating equal to the sum of their rated full-load currents, a hoist or trolley shall be considered to be protected if the sensing device is connected in the hoist's upper limit switch circuit so as to prevent further hoisting during an overtemperature condition of either motor.