The provisions of Article 552 of NFPA 70 are adopted by reference with the following modification:
1. Revise section 552.48 to read:
"Wiring Methods.
(A) Wiring Systems. Cables and raceways shall be installed in accordance with the permissible Chapter 3 wiring methods, except as otherwise specified in this article. An equipment grounding means shall be provided in accordance with 250.118.
(B) Conduit and Tubing. Where rigid metal conduit or intermediate metal conduit is terminated at an enclosure with a locknut and bushing connection, two locknuts shall be provided, one inside and one outside of the enclosure. All cut ends of conduit and tubing shall be reamed or otherwise finished to remove rough edges.
(C) Boxes. In walls and ceilings constructed of wood or other combustible material, boxes and fittings shall be flush with the finished surface or project therefrom.
(D) Mounting. Wall and ceiling boxes shall be mounted in accordance with Article 314.
Exception No. 1: Snap-in-type boxes or boxes provided with special wall or ceiling brackets that securely fasten boxes in walls or ceilings shall be permitted.
Exception No. 2: A wooden plate providing a 1-1/2 in. minimum width backing around the box and of a thickness of 1/2 in. or greater (actual) attached directly to the wall panel shall be considered as approved means for mounting outlet boxes.
(E) Raceway and Cable Continuity. Raceways and cable, shall be continuous between outlet boxes and other enclosures.
(F) Protected. Electrical metallic tubing shall be permitted to pass through the centers of the wide side of 2x4 wood studs. However, they shall be protected where they pass through 2x2 wood studs or at other wood studs or frames where the cable or tubing would be less than 31.8 mm (1-1/4 in.) from the inside or outside surface. Steel plates on each side of the cable or tubing or a steel tube, with not less than 0.053 in. wall thickness, shall be installed to protect the cable or tubing.
(G) Cable Supports. Where connected with cable connectors or clamps, cables shall be secured and supported within 305 mm (12 in.) of outlet boxes, panelboards, and splice boxes on appliances. Supports and securing shall be provided at intervals not exceeding 1.37 m (4.5 ft) at other places.
(H) Physical Damage. Where subject to physical damage, exposed nonmetallic cable shall be installed in metal raceways.
(I) Receptacle Faceplates. Metal faceplates shall comply with 406.5(A). Nonmetallic faceplates shall comply with 406.5(C).
(J) Metal Faceplates Grounded. Where metal faceplates are used, they shall be grounded.
(K) Moisture or Physical Damage. Where outdoor or under-chassis wiring is 120 volts, nominal, or over and is exposed to moisture or physical damage, the wiring shall be protected by rigid metal conduit, by intermediate metal conduit, by electrical metallic tubing, or by Type MI cable that is closely routed against frames and equipment enclosures or other raceway or cable identified for the application.
(L) Component Interconnections. Fittings and connectors that are intended to be concealed at the time of assembly shall be listed and identified for the interconnection of building components. Such fittings and connectors shall be equal to the wiring method employed in insulation, temperature rise, and fault- current withstanding, and shall be capable of enduring the vibration and shock occurring in park trailers.
(M) Method of Connecting Expandable Units. The method of connecting expandable units to the main body of the park trailer shall comply with the following as applicable:
(1) Cord-and-Plug Connected. Cord-and-plug connections shall comply with 552.48(M)(1)(a) through (M)(1)(d).
(a) The portion of a branch circuit that is installed in an expandable unit shall be permitted to be connected to the portion of the branch circuit in the main body of the vehicle by means of a flexible cord or attachment plug and cord listed for hard usage. The cord and its connections shall comply with all provisions of Article 400 and shall be considered as a permitted use under 400.10.
(b) Where the receptacle provided for connection of the cord to the main circuit is located on the outside of the park trailer, it shall be protected with a ground-fault circuit interrupter for personnel and be listed for wet locations. A cord located on the outside of a park trailer shall be identified for outdoor use.
(c) Unless removable or stored within the park trailer interior, the cord assembly shall have permanent provisions for protection against corrosion and mechanical damage while the park trailer is in transit.
(d) The attachment plug and cord shall be installed so as not to permit exposed live attachment plug pins.
(2) Direct Wires Connected. That portion of a branch circuit that is installed in an expandable unit shall be permitted to be connected to the portion of the branch circuit in the main body of the park trailer by means of flexible cord installed in accordance with 552.48(M)(2)(a) through (M)(2)(f) or other approved wiring method.
(a) The flexible cord shall be listed for hard usage and for use in wet locations.
(b) The flexible cord shall be permitted to be exposed on the underside of the vehicle.
(c) The flexible cord shall be permitted to pass through the interior of a wall or floor assembly or both a maximum concealed length of 610 mm (24 in.) before terminating at an outlet or junction box.
(d) Where concealed, the flexible cord shall be installed in nonflexible conduit or tubing that is continuous from the outlet or junction box inside the park trailer to a weatherproof outlet box, junction box, or strain relief fitting listed for use in wet locations that is located on the underside of the park trailer. The outer jacket of flexible cord shall be continuous into the outlet or junction box.
(e) Where the flexible cord passes through the floor to an exposed area inside of the park trailer, it shall be protected by means of conduit and bushings or equivalent.
(f) Where subject to physical damage, the flexible cord shall be protected with RMC, IMC, Schedule 80 PVC, reinforced thermosetting resin conduit (RTRC) listed for exposure to physical damage, or other approved means and shall extend at least 6 in. above the floor. A means shall be provided to secure the flexible cord where it enters the park trailer.
(N) Prewiring for Air-Conditioning Installation. Prewiring installed for the purpose of facilitating future air-conditioning installation shall comply with the applicable portions of this article and the following:
(1) An overcurrent protective device with a rating compatible with the circuit conductors shall be installed in the distribution panelboard and wiring connections completed.
(2) The load end of the circuit shall terminate in a junction box with a blank cover or other listed enclosure. Where a junction box with a blank cover is used, the free ends of the conductors shall be adequately capped or taped.
(3) A safety label with the signal word WARNING in minimum 1/4 in. high letters and body text in minimum 1/8 in. high letters on a contrasting background. The safety label shall be affixed on or adjacent to the junction box and shall read:
AIR-CONDITIONING CIRCUIT. THIS CONNECTION IS FOR AIR CONDITIONERS RATED 110 – 125-VOLT AC, 60 HZ, ___ AMPERES MAXIMUM. DO NOT EXCEED CIRCUIT RATING. EXCEEDING THE CIRCUIT RATING MAY CAUSE A FIRE AND RESULT IN DEATH OR SERIOUS INJURY.
An ampere rating, not to exceed 80 percent of the circuit rating, shall be legibly marked in the blank space.
(4) The circuit shall serve no other purpose.
(O) Prewiring for Other Circuits. Prewiring installed for the purpose of installing other appliances or devices shall comply with the applicable portions of this article and the following:
(1) An overcurrent protection device with a rating compatible with the circuit conductors shall be installed in the panelboard with wiring connections completed.
(2) The load end of the circuit shall terminate in a junction box with a blank cover or a device listed for the purpose. Where a junction box with blank cover is used, the free ends of the conductors shall be adequately capped or taped.
(3) A safety label with the signal word WARNING in minimum 1/4 in. high letters and body text in minimum 1/8 in. high letters on a contrasting background. The safety label shall be affixed to the junction box or device listed for the purpose and shall read:
THIS CONNECTION IS FOR ____ RATED ____ VOLT AC, 60 HZ, ____ AMPERES MAXIMUM. DO NOT EXCEED THE CIRCUIT RATING. EXCEEDING THE CIRCUIT RATING MAY CAUSE A FIRE AND RESULT IN DEATH OR SERIOUS INJURY.
The intended appliance type shall be legibly marked in the first blank space. An ampere rating not to exceed 80 percent of the circuit rating shall be legibly marked in the second blank space."