(M) Metal Faceplates Grounded. Where metal faceplates are used, they shall be grounded.

(N) 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, or by electrical metallic

tubing, rigid nonmetallic conduit, or Type MI cable, that is closely routed against frames and equipment enclosures or other raceway or cable identified for the application.

(0) 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 recreational vehicles.

(P) Method of Connecting Expandable Units. The method of connecting expandable units to the main body of the vehicle shall comply with 551.47(P)(1) or (P)(2):

(1) Cord-and-Plug-Connected. Cord-and-plug connec tions shall comply with (a) through (d).

(a) 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 vehicle by means of an 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
400.7. Where the attachment plug and cord are
located within the vehicle's interior, use of plastic
thermoset or elastomer parallel cord Type SPT-3, SP-
3, or SPE shall be permitted.

(b) Where the receptacle provided for connection

of the cord to the main circuit is located on the
outside of the vehicle, 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 vehicle shall be identified for outdoor use.

(c) Unless removable or stored within the vehicle

interior, the cord assembly shall have permanent
provisions for protection against corrosion and
mechanical damage while the vehicle is in transit.

(d) The attachment plug and cord shall be

installed so as not to permit exposed live attachment
plug pins.

(2) Direct Wired. 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 vehicle by means of flexible cord installed in accordance with 551.47(P)(2)(a) through (P)(2)(e) 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 600 mm (24 in.)

before terminating at an outlet or junction box.

(d) Where concealed, the flexible cord shall be in- stalled in nonflexible