National Electrical Code


A. General

530-1. Scope.

The requirements of this article shall apply to television studios and motion picture studios using either film or electronic cameras, except as provided in Section 520-1, and exchanges, factories, laboratories, stages, or portion of the building in which film or tape more than 7/8 in. (22 mm) in width is exposed, developed, printed, cut, edited, rewound, repaired, or stored.

(FPN): For methods of protecting against cellulose nitrate film hazards, see Standard for the Storage and Handling of Cellulose Nitrate Motion Picture Film, NFPA 40-1994

530-2 Definitions.

AC Power Distribution Box (AC Plugging Box, Scatter Box): An ac distribution center or box that contains one or more grounded, polarized receptacles, that may contain overcurrent protection devices.

Bull Switch: An externally-operated wall mounted safety switch, which may or may not contain overcurrent protection, that is designed for the connection of portable cables and cords.

Location (Shooting Location): A place outside a motion picture studio where a production or part of it is filmed or recorded.

Location Board (Deuce Board): Portable equipment containing a lighting contactor or contactors and overcurrent protection designed for remote control of stage lighting.

Motion Picture Studio (Lot): A building or group of buildings and other structures designed, constructed, or permanently altered for use by the entertainment industry for the purpose of motion picture or television production.

Portable Equipment: Equipment intended to be moved from one place to another.

Plugging Box: A dc device consisting of one or more 2-pole, 2-wire, nonpolarized ungrounded receptacles intended to be used on dc circuits only.

Single-Pole Separable Connector: A device that is installed at the ends of portable, flexible, single-conductor cable that is used to establish connection or disconnection between two cables or one cable and a single-pole, panel-mounted separable connector.

Spider (Cable Splicing Block): A device that contains busbars that are insulated from each other for the purpose of splicing or distributing power to portable cables and cords that are terminated with single-pole busbar connectors.

Stage Effect (Special Effect): An electrical or electromechanical piece of equipment used to simulate a distinctive visual or audible effect such as wind machines, lightning simulators, sunset projectors, and the like.

Stage Property: An article or object used as a visual element in a motion picture or television production, except painted backgrounds (scenery) and costumes.

Stage Set: A specific area set up with temporary scenery and properties designed and arranged for a particular scene in a motion picture or television production.

Stand Lamp (Work Light): A portable stand that contains a general-purpose lighting fixture or lampholder with guard for the purpose of motion picture, television, or commercial production.

530-11. Permanent Wiring.

The permanent wiring shall be Type MC cable, Type MI cable, or in approved raceways.

Exception: Communications circuits, sound-recording and reproducing circuits, Class 2 and Class 3 remote-control or signaling circuits and power-limited fire alarm circuits shall be permitted to be wired in accordance with Articles 640, 725, 760, and 800.

530-12. Portable Wiring.

The wiring for stage set lighting, stage effects, electric equipment used as stage properties, and other wiring not fixed as to location shall be done with approved flexible cords used to supply stage properties where such are made with approved devices and the circuit is protected at not more than 20 amperes. Such cables and cords shall not be fastened by staples or nailing.

530-13. Stage Lighting and Effects Control.

Switches used for studio stage set lighting and effects (on the stages and lots and on location) shall be of the externally operable type. Where contactors are used as the disconnecting means for fuses, an individual externally operable switch, such as a tumbler switch, for the control of each contactor shall be located at a distance of not more than 6 ft (1.83 m) from the contactor, in addition to remote-control switches.

530-14. Plugging Boxes.

Each receptacle of dc plugging boxes shall be rated at not less than 30 amperes.

530-15. Enclosing and Guarding Live Parts.

(a) Live Parts. Live parts shall be enclosed or guarded to prevent accidental contact by persons and objects.

(b) Switches. All switches shall be of the externally operable type.

(c) Rheostats. Rheostats shall be placed in approved cases or cabinets that enclose all live parts, having only the operating handles exposed.

(d) Current-Carrying Parts. Current-carrying parts of bull-switches, location boards, spiders, and plugging boxes shall be so enclosed, guarded, or located that persons cannot accidentally come into contact with them or bring conductive material into contact with them.

530-16. Portable Lamps.

Portable lamps and work lights shall be equipped with flexible cords, composition or metal-sheathed porcelain sockets, and substantial guards.

Exception: Portable lamps used as properties in a motion picture set or television stage set, on a studio stage or lot, or on location.

530-17. Portable Arc Lamp Fixtures.

(a) Portable Carbon Arc Lamps. Portable carbon arc lamps shall be substantially constructed. The arc shall be provided with an enclosure designed to retain sparks and carbons and to prevent persons or materials from coming into contact with the arc or bare live parts. The enclosures shall be ventilated. All switches shall be of the externally-operable type.

(b) Portable Noncarbon Arc Electric-Discharge Lamp Fixtures. Portable noncarbon arc lamp fixtures, including enclosed arc lamp fixtures, and associated ballasts shall be listed. Interconnecting cord sets, and interconnecting cords and cables, shall be extra-hard usage type and listed.

530-18. Overcurrent Protection.

General. Automatic overcurrent protective devices (circuit breakers or fuses) for motion picture studios stage set lighting and the stage cables for such stage set lighting shall be as given in (a) through (f) below. The maximum ampacity allowed on a given conductor, cable, or cord size shall be as given in applicable tables of Article 310 and 400.

(a) Stage Cables. Stage cables for stage set lighting shall be protected by means of overcurrent devices set at not more than 400 percent of the ampacity given in applicable tables of Articles 310 and 400.

(b) Feeders. In buildings used primarily for motion picture production, the feeders from the substations to the stages shall be protected by means of overcurrent devices (generally located in the substation) having suitable ampere rating. The overcurrent devices shall be permitted to be multipole or single-pole gang-operated. No pole or over current device shall be required in the neutral conductor. The overcurrent device setting for each feeder shall not exceed 400 percent of the ampacity of the feeder, as given in applicable tables of Article 300.

(c) Location Boards. Overcurrent protection (fuses or circuit breakers) shall be provided at the location boards. Fuses in the location boards shall have an ampere rating of not over 400 percent of the ampacity of the cables between the location boards and the plugging boxes.

(d) Plugging Boxes. Cables and cords supplied through plugging boxes shall be of copper. Cables and cords smaller than No. 8 shall be attached to the plugging box by means of a plug containing two cartridge fuses or a 2-pole circuit breaker. The rating of the fuses or the setting of the circuit breaker shall not be over 400 percent of the rated ampacity of the cables or cords as given in applicable tables of Articles 310 and 400. Plugging boxes shall not be permitted on ac systems.

(e) AC Power Distribution Boxes. AC power distribution boxes used on sound stages and shooting locations shall contain connection receptacles of a polarized grounding type.

(f) Lighting. Work light, stand lamps and fixtures, rated 1,000 watts or less and connected to dc plugging boxes, shall be by means of plugs containing two cartridge fuses not larger than 20 amperes, or they shall be permitted to be connected to special outlets on circuits protected by fuses or circuit breakers rated at not over 20 amperes. Plug fuses shall not be used unless they are on the load side of the fuse or circuit breakers on the location boards.

530-19. Sizing of Feeders Conductors for Television Studio Sets.

(a) General. It shall be permissible to apply the demand factors listed inTable 530-19(a) to the portion of the maximum possible connected load for studio or stage set lighting for all permanently installed feeders between substations and stages and to all permanently installed feeders between the main stage switchboard and stage distribution centers or location boards.

(b) Portable Feeders. A demand factor of 50 percent of maximum possible connected load shall be permitted for all portable feeders.

Table 520-19(a). Demand Factors for Stage Set Lighting

Portion of Stage Set Lighting Load to Which Demand Factor Applied (volt-amperes) Feeder Demand Factor
First 50,000 or less at 100%
From 50,001 to 100,000 at 75%
From 100,001 to 200,000 at 60%
Remaining over 200,000 at 50%

530-20. Grounding.

Type MC cable, Type MI cable, metal raceways, and all noncurrent-carrying metal parts of appliances, devices, and equipment shall be grounded as specified in Article 250. This shall not apply to pendant and portable lamps, to stage lighting and stage sound equipment, nor to other portable and special stage equipment operating at not over 150 volts dc to ground.

530-21. Plugs and Receptacles.

(a) Rating. Plug and receptacles shall be rated in amperes. The voltage rating of the plugs and receptacles shall not be less than the circuit voltage. Plug and receptacle ampere ratings for ac circuits shall not be less than the feeder or branch circuit over current device ampere rating. Table 210-21(b)(2) shall not apply.

(b) Interchangeability. Plugs and receptacles used in portable professional motion picture and television equipment shall be permitted to be interchangeable for ac or dc use on the same premises provided they are listed for ac/dc use and marked in a suitable manner to identify the system to which they are connected.

530-22 Single-Pole Separable Connectors.

Where ac single-pole portable cable connectors are used, they shall be listed and of the locking type. Where paralleled sets of current carrying single-pole separable connectors are provided as input devices, they shall be prominently labeled with a warning indicating the presence of internal parallel connections. The use of such connectors shall comply with at least one of the following conditions:

(1) Connection and disconnection of connectors are only possible where the supply connectors are interlocked to the source and it is not possible to connect or disconnect connectors when the supply is energized.

(2) Line connectors are of the listed sequential-interlocking type so that load connectors shall be connected in the following sequence.

(a) Equipment grounding conductor connection.

(b) Grounded circuit conductor connection, if provided.

(c) Ungrounded conductor connection, and that disconnection shall be in the reverse order.

(3) A caution notice shall be provided adjacent to the line connectors indicating the plug connection shall be in the following order:

(a) Equipment grounding conductor connectors.

(b) Grounded circuit conductor connectors, if provided.

(c) Ungrounded conductor connectors, and that disconnection shall be in the reverse order.

530-23. Branch Circuits.

A branch circuit of any size supplying one or more receptacles shall be permitted to supply stage set lighting loads.

C. Dressing Rooms.

530-31. Dressing Rooms.

Fixed wiring in dressing rooms shall be installed in accordance with wiring methods covered in Chapter 3. Wiring for portable dressing rooms shall be approved.