MOTION PICTURE STUDIOS

70-579 (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 lights, stand lamps, and fixtures, where 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 Feeder Conductors for Television Studio Sets. (a) General. It shall be permissible to apply the demand factors listed in Table 530-19(a) to that 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. Table 530-19(a). Demand Factors for Stage Set Lighting Portion of Stage Set Lighting Feeder Demand Load to Which Demand Factor Factor Applied (volt-amperes) 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% (b) Portable Feeders. A demand factor of 50 percent of maximum possible connected load shall be permitted for all portable feeders. 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. Single-Pole Separable Connectors. Where single-pole portable cable connectors are used, they shall be listed and of the locking type. The use of such connectors shall comply with at least one of the following conditions: 70-580 NATIONAL ELECTRICAL CODE (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 that 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. 530-22. 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. D. Viewing, Cutting, and Patching Tables 530-41. Lamps at Tables. Only composition or metal-sheathed, porcelain, keyless lampholders equipped with suitable means to guard lamps from physical damage and from film and film scrap shall be used at patching, viewing, and cutting tables. E. Cellulose Nitrate Film Storage Vaults 530-51. Lamps in Cellulose Nitrate Film Storage Vaults. Lamps in cellulose nitrate film storage vaults shall be installed in rigid fixtures of the glass enclosed and gasketed type. Lamps shall be controlled by a switch having a pole in each ungrounded conductor. This switch shall be located outside of the vault and provided with a pilot light to indicate whether the switch is on or off. This switch shall disconnect from all sources of supply all ungrounded conductors terminating in any outlet in the vault. 530-52. Motors and Other Equipment in Cellulose Nitrate Film Storage Vaults. Except as permitted in Section 530-51, no receptacles, outlets, electric motors, heaters, portable lights, or other portable electric equipment shall be located in cellulose nitrate film storage vaults.