Resolución 2535: adopta el Código Eléctrico Nacional, versión 1993. (Sustituye el Anejo A del Reglamento 4435)

520-53. Construction and Feeders. Portable switchboards and feeders for use on stages shall comply with (a) through (p) below. (a) Enclosure. Portable switchboards shall be placed within an enclosure of substantial construction, which shall be permitted to be so arranged that the enclosure is open during operation. Enclosures of wood shall be completely lined with sheet metal of not less than No. 24 MSG and shall be well-galvanized, enameled, or otherwise properly coated to prevent corrosion or be of a corrosion-resistant material. (b) Energized Parts. There shall not be exposed energized parts within the enclosure. Exception: For dimmer faceplates as provided in (e) below. (c) Switches and Circuit Breakers. All switches and circuit breakers shall be of the externally operable, enclosed type. (d) Circuit Protection. Overcurrent devices shall be provided in each ungrounded conductor of every circuit supplied through the switchboard. Enclosures shall be provided for all overcurrent devices in addition to the switchboard enclosure. (e) Dimmers. The terminals of dimmers shall be provided with enclosures, and dimmer faceplates shall be so arranged that accidental contact cannot be readily made with the faceplate contacts. (f) Interior Conductors. All conductors other than busbars within the switchboard enclosure shall be stranded. Conductors shall be approved for an operating temperature at least equal to the approved operating temperature of the dimming devices used in the switchboard and in no case less than the following: (1) resistance-type dimmers, 200°C (392°F); or (2) reactor-type, autotransformer, and solid-state dimmers, 125°C (257°F). All control wiring shall comply with Article 725. Each conductor shall have an ampacity not less than the rating of the circuit breaker, switch, or fuse that it supplies. Circuit interrupting and bus bracing shall be in accordance with Sections 110-9 and 110-10. Switchboards with inadequate short-circuit withstand rating shall be protected on the line side by current-limiting devices. The short-circuit withstand rating shall be marked on the switchboard. ARTICLE 520 - THEATERS AND SIMILAR LOCATIONS 70-571 Exception: Conductors for pilot light circuits having overcurrent protection of not over 20 amperes. Conductors shall be enclosed in metal wireways or be securely fastened in position and shall be bushed where they pass through metal. (g) Pilot Light. A pilot light shall be provided within the enclosure and shall be so connected to the circuit supplying the board that the opening of the master switch will not cut off the supply to the lamp. This lamp shall be on an individual branch circuit having overcurrent protection rated or set at not over 15 amperes. (h) Supply Conductors. The supply to a portable switchboard shall be by means of listed extra-hard usage cords or cables. The supply cords or cable shall terminate within the switchboard enclosure, in an externally operable fused master switch or circuit breaker, or in a connector assembly identified for the purpose. The supply cords or cable (and connector assembly) shall have sufficient ampacity to carry the total load connected to the switchboard and shall be protected by overcurrent devices. Single-conductor portable supply cable sets shall not be smaller than No. 2 conductors. The equipment grounding conductor shall not be smaller than No. 6 conductor. The single-conductor cables for a supply shall be of the same length, type, size, and be grouped together, but not bundled. The equipment grounding conductor shall be permitted to be of a different type, provided it meets the other requirements of this section, and it shall be permitted to be reduced in size as permitted by Section 250-95. Grounded (neutral) and equipment grounding conductors shall be identified in accordance with Sections 200-6, 250-57(b), and 310-12. Grounded conductors shall be permitted to be identified by marking at least the first 6 inches (152.4 mm) from both ends of each length of conductor with white or natural gray. Equipment grounding conductors shall be permitted to be identified by marking at least the first 6 inches (152.4 mm) from both ends of each length of conductor with green or green with yellow stripes. Where more than one nominal voltage exists within the same premises, each ungrounded system conductor shall be identified by system. Exception No. 1: Supply Conductors Not Over 10 Feet (3.05 m) Long. In cases where supply conductors do not exceed 10 feet (3.05 m) in length between supply and switchboard or supply and a subsequent overcurrent device, the ampacity of the supply conductors shall be at least one-quarter of the ampacity of the supply overcurrent protection device where all of the following conditions are met: a. The supply conductors shall terminate in a single overcurrent protection device that will limit the load to the ampacity of the supply conductors. This single overcurrent device shall be permitted to supply additional overcurrent devices on its load side. b. The supply conductors shall not penetrate walls, floors, or ceilings or be run through doors or traffic areas. The supply conductors shall be adequately protected from physical damage. c. The supply conductors shall be suitably terminated in an approved manner. d. Conductors shall be continuous without splices or connectors. e. Conductors shall not be bundled. f. Conductors shall be supported above the floor in an approved manner. 70-572 NATIONAL ELECTRICAL CODE Exception No. 2: Supply Conductors Not Over 20 Feet (6.1 m) Long. In cases where supply conductors do not exceed 20 feet (6.1 m) in length between supply and switchboard or supply and a subsequent overcurrent protection device, the ampacity of the supply conductors shall be at least one-half the rating of the supply overcurrent protection device where all of the following conditions are met: a. The supply conductors shall terminate in a single overcurrent protection device that will limit the load to the ampacity of the supply conductors. This single overcurrent device shall be permitted to supply additional overcurrent devices on its load side. b. The supply conductors shall not penetrate walls, floors, or ceilings or be run through doors or traffic areas. The supply conductors shall be adequately protected from physical damage. C. The supply conductors shall be suitably terminated in an approved manner. d. The supply conductors shall be supported in an approved manner at least 7 feet (2.13 m) above the floor except at terminations. e. The supply conductors shall not be bundled. f. -Tap conductors shall be in unbroken lengths. (i) Cable Arrangement. Cables shall be protected by bushings where they pass through enclosures and shall be so arranged that tension on the cable will not be transmitted to the connections. Where power conductors pass through metal, the requirements of Section 300-20 shall apply. (j) Number of Supply Interconnections. Where connectors are used in a supply conductor, there shall be a maximum number of three interconnections (mated connector pairs) where the total length from supply to switchboard does not exceed 100 feet (30.5 m). In cases where the total length from supply to switchboard exceeds 100 feet (30.5 m), one additional interconnection shall be permitted for each additional 100 feet (30.5 m) of supply conductor. (k) 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: (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: ARTICLE 520 - THEATERS AND SIMILAR LOCATIONS 70-573 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. (I) Protection of Supply Conductors and Connectors. All supply conductors and connectors shall be protected against physical damage by an approved means. This protection shall not be required to be raceways. (m) Flanged Surface Inlets. Flanged surface inlets (recessed plugs) that are used to accept the power shall be rated in amperes. (n) Terminals. Terminals to which stage cables are connected shall be so located as to permit convenient access to the terminals. (o) Supply Neutral Terminal. In portable switchboard equipment designed for use with 3-phase, 4-wire with ground supply, the supply neutral terminal, its associated busbar, or equivalent wiring, or both, shall have an ampacity equal to twice the ampacity of the largest ungrounded supply terminal. The power supply lines for portable switchboards shall be sized considering the neutral as a current-carrying conductor. Where single-conductor feeder cables, not installed in raceways, are used on multiphase circuits, the grounded neutral conductor shall have an ampacity of 130 percent of the ungrounded circuit conductors feeding the portable switchboard. Exception: Where portable switchboard equipment is specifically constructed and identified to be internally converted in the field, in an approved manner, from use with a balanced 3-phase, 4-wire with ground supply to a balanced single-phase, 3-wire with ground supply, the supply neutral terminal and its associated busbar, equivalent wiring, or both, shall have an ampacity equal to that of the largest ungrounded singlephase supply terminal. (p) Qualified Personnel. The routing of portable supply conductors, the making and breaking of supply connectors and other supply connections, and the energization and deenergization of supply services shall be performed by qualified personnel, and portable switchboards shall be so marked, indicating this requirement in a permanent and conspicuous manner. Exception: Connection of a portable switchboard to a permanently installed supply receptacle outlet, that supply receptacle outlet being protected for its rated ampacity by an overcurrent device of not greater than 150 amps, and where the receptacle outlet, interconnection, and switchboard further: a. Employ listed multipole connectors suitable for the purpose for every supply interconnection, and b. Prevent access to all supply connections by the general public, and C. Employ listed extra-hard usage multiconductor cords or cables with an ampacity suitable for the type of load and not less than the ampere rating of the connectors. 70-574 NATIONAL ELECTRICAL CODE E. Stage Equipment - Portable 520-61. Arc Lamp Fixtures. 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. 520-62. Portable Plugging Boxes. Portable plugging boxes shall comply with (a) through (e) below. (a) Enclosure. The construction shall be such that no current-carrying part will be exposed. (b) Receptacles and Overcurrent Protection. Receptacles shall comply with Section 520-45 and shall have branch-circuit overcurrent protection in the box. Fuses and circuit breakers shall be protected against physical damage. Cords or cables supplying pendant receptacles shall be listed for extra-hard usage. (c) Busbars and Terminals. Busbars shall have an ampacity equal to the sum of the ampere ratings of all the circuits connected to the busbar. Lugs shall be provided for the connection of the master cable. (d) Flanged Surface Inlets. Flanged surface inlets (recessed plugs) that are used to accept the power shall be rated in amperes. (e) Cable Arrangement. Cables shall be adequately protected where they pass through enclosures and be so arranged that tension on the cable will not be transmitted to the terminations. 520-63. Bracket Fixture Wiring. (a) Bracket Wiring. Brackets for use on scenery shall be wired internally, and the fixture stem shall be carried through to the back of the scenery where a bushing shall be placed on the end of the stem. Exception: Externally wired brackets or other fixtures shall be permitted where wired with cords designed for hard usage that extend through scenery and without joint or splice in canopy of fixture back and terminate in an approved-type stage connector located, where practical, within 18 inches (457 mm) of the fixture. (b) Mounting. Fixtures shall be securely fastened in place. 520-64. Portable Strips. Portable strips shall be constructed in accordance with the requirements for border lights and proscenium side lights in