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(A) Low-Voltage Circuits
Low-voltage circuits furnished and installed by the park trailer manufacturer, other than those related to braking, shall be subject to this Code. Circuits supplying lights subject to federal or state regulations shall comply with applicable government regulations and this Code.
(B) Low-Voltage Wiring
(1) Material
Copper conductors shall be used for low-voltage circuits.
Exception: A metal chassis or frame shall be permitted as the return path to the source of supply.
(2) Conductor Types
Conductors shall conform to the requirements for Type GXL, HDT, SGT, SGR, or Type SXL or shall have insulation in accordance with Table 310.4(A) or the equivalent. Conductor sizes 6 AWG through 18 AWG or SAE shall be listed. Single-wire, low-voltage conductors shall be of the stranded type.
Informational Note: See SAE J1128-2015, Low Voltage Primary Cable, for Types GXL, HDT, and SXL, and SAE J1127-2015, Low Voltage Battery Cable, for Types SGT and SGR.
(3) Marking
All insulated low-voltage conductors shall be surface marked at intervals not greater than 1.2 m (4 ft) as follows:
  1. Listed conductors shall be marked as required by the listing agency.
  2. SAE conductors shall be marked with the name or logo of the manufacturer, specification designation, and wire gauge.
  3. Other conductors shall be marked with the name or logo of the manufacturer, temperature rating, wire gauge, conductor material, and insulation thickness.
(C) Low-Voltage Wiring Methods
(1) Physical Protection
Conductors shall be protected against physical damage and shall be secured. Where insulated conductors are clamped to the structure, the conductor insulation shall be supplemented by an additional wrap or layer of equivalent material, except that jacketed cables shall not be required to be so protected. Wiring shall be routed away from sharp edges, moving parts, or heat sources.
(2) Splices
Conductors shall be spliced or joined with splicing devices that provide a secure connection or by brazing, welding, or soldering with a fusible metal or alloy. Soldered splices shall first be spliced or joined to be mechanically and electrically secure without solder, and then soldered. All splices, joints, and free ends of conductors shall be covered with an insulation equivalent to that on the conductors.
(3) Separation
Battery and other low-voltage circuits shall be physically separated by at least a 13-mm (1/2-in.) gap or other approved means from circuits of a different power source. Acceptable methods shall be by clamping, routing, or equivalent means that ensure permanent total separation. Where circuits of different power sources cross, the external jacket of the nonmetallic-sheathed cables shall be deemed adequate separation.
(4) Ground Connections
Ground connections to the chassis or frame shall be made in an accessible location and shall be mechanically secure. Ground connections shall be by means of copper conductors and copper or copper-alloy terminals of the solderless type identified for the size of wire used. The surface on which ground terminals make contact shall be cleaned and be free from oxide or paint or shall be electrically connected through the use of a cadmium, tin, or zinc-plated internal/external-toothed lockwasher or locking terminals. Ground terminal attaching screws, rivets or bolts, nuts, and lockwashers shall be cadmium, tin, or zinc-plated except rivets shall be permitted to be unanodized aluminum where attaching to aluminum structures.
The chassis-grounding terminal of the battery shall be connected to the unit chassis with a minimum 8 AWG copper conductor. In the event the unbonded lead from the battery exceeds 8 AWG, the bonding conductor size shall be not less than that of the unbonded lead.
(D) Battery Installations
Storage batteries subject to this Code shall be securely attached to the unit and installed in an area vaportight to the interior and ventilated directly to the exterior of the unit. Where batteries are installed in a compartment, the compartment shall be ventilated with openings having a minimum area of 1100 mm2 (1.7 in.2) at both the top and at the bottom. Where compartment doors are equipped for ventilation, the openings shall be within 50 mm (2 in.) of the top and bottom. Batteries shall not be installed in a compartment containing spark- or flame-producing equipment.
(E) Overcurrent Protection
(1) Rating
Low-voltage circuit wiring shall be protected by overcurrent protective devices rated not in excess of the ampacity of copper conductors, in accordance with Table 552.10(E)(1).
Table 552.10(E)(1) Low-Voltage Overcurrent Protection
Wire Size (AWG) Ampacity Wire Type
18 6 Stranded only
16 8 Stranded only
14 15 Stranded or solid
12 20 Stranded or solid
10 30 Stranded or solid
(2) Type
Circuit breakers or fuses shall be of an approved type, including automotive types. Fuseholders shall be clearly marked with maximum fuse size and shall be protected against shorting and physical damage by a cover or equivalent means.
Informational Note: For further information, see ANSI/SAE J554-1987, Standard for Electric Fuses (Cartridge Type); SAE J1284-1988, Standard for Blade Type Electric Fuses; and UL 275-2005, Standard for Automotive Glass Tube Fuses.
(3) Appliances
Appliances such as pumps, compressors, heater blowers, and similar motor-driven appliances shall be installed in accordance with the manufacturer's instructions.
Motors that are controlled by automatic switching or by latching-type manual switches shall be protected in accordance with 430.32(B).
(4) Location
The overcurrent protective device shall be installed in an accessible location on the unit within 450 mm (18 in.) of the point where the power supply connects to the unit circuits. If located outside the park trailer, the device shall be protected against weather and physical damage.
Exception: External low-voltage supply shall be permitted to have the overcurrent protective device within 450 mm (18 in.) after entering the unit or after leaving a metal raceway.
(F) Switches
Switches shall have a dc rating not less than the connected load.
(G) Luminaires
All low-voltage interior luminaires rated more than 4 watts, employing lamps rated more than 1.2 watts, shall be listed.

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552.10 Special Occupancies, Low-Voltage Systems
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