MOTION PICTURE STUDIOS

70-577 530-2. Definitions. 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. 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. B. Stage or Set 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 protective signaling 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 and cables. Splices or taps shall be permitted in 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 feet (1.83 m) from the contactor, in addition to remote-control switches. Exception: A single externally operable switch shall be permitted to simultaneously disconnect all the contactors on any one location board, where located at a distance of not more than 6 feet (1.83 m) from the location board. 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. 70-578 NATIONAL ELECTRICAL CODE (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 - Short-Time Rating.* General. Automatic overcurrent protective devices (circuit breakers or fuses) for motion picture studio stage set lighting and the stage cables for such stage set lighting shall be as given in (a) through (f) below. (FPN): Note: * Special consideration is given to motion picture studios and similar locations, because filming periods are of short duration of 20 minutes. (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 overcurrent 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 310. Short-term ratings shall not be permitted when equipment is operated for periods in excess of 20 minutes. (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.