RECREATIONAL VEHICLES, PARKS

70-605 with or without switches and/or automatic overcurrent-protective devices for the control of light, heat, or power circuits of small individual as well as aggregate capacity; designed to be placed in a cabinet or cutout box placed in or against a wall or partition and accessible only from the front. Frame: Chassis rail and any welded addition thereto of metal thickness of 16 MSG or greater. Low Voltage: An electromotive force rated 24 volts, nominal, or less, supplied from a transformer, converter, or battery. Motor Home: A vehicular unit designed to provide temporary living quarters for recreational, camping, or travel use built on or permanently attached to a self-propelled motor vehicle chassis or on a chassis cab or van that is an integral part of the completed vehicle. (See "Recreational Vehicle.") Power-Supply Assembly: The conductors, including ungrounded, grounded, and equipment grounding conductors, the connectors, attachment plug caps, and all other fittings, grommets, or devices installed for the purpose of delivering energy from the source of electrical supply to the distribution panel within the recreational vehicle. Recreational Vehicle: A vehicular-type unit primarily designed as temporary living quarters for recreational, camping, or travel use, which either has its own motive power or is mounted on or drawn by another vehicle. The basic entities are: travel trailer, camping trailer, truck camper, and motor home. Recreational Vehicle Park. A plot of land upon which two or more recreational vehicle sites are located, established, or maintained for occupancy by recreational vehicles of the general public as temporary living quarters for recreation or vacation purposes. Recreational Vehicle Site. A plot of ground within a recreational vehicle park intended for the accommodation of either a recreational vehicle, tent, or other individual camping unit on a temporary basis. Recreational Vehicle Site Feeder Circuit Conductors. The conductors from the park service equipment to the recreational vehicle site supply equipment. Recreational Vehicle Site Supply Equipment. The necessary equipment, usually a power outlet, consisting of a circuit breaker or switch and fuse and their accessories, located near the point of entrance of supply conductors to a recreational vehicle site and intended to constitute the disconnecting means for the supply to that site. Recreational Vehicle Stand. That area of a recreational vehicle site intended for the placement of a recreational vehicle. Transformer: A device that, when used, will raise or lower the voltage of alternating current of the original source. 70-606 NATIONAL ELECTRICAL CODE Travel Trailer: A vehicular unit mounted on wheels, designed to provide temporary living quarters for recreational, camping, or travel use, of such size or weight as not to require special highway movement permits when towed by a motorized vehicle, and of gross trailer area less than 320 square feet (29.77 sq m). (See "Recreational Vehicle.") Truck Camper: A portable unit constructed to provide temporary living quarters for recreational, travel, or camping use, consisting of a roof, floor, and sides, designed to be loaded onto and unloaded from the bed of a pick-up truck. (See "Recreational Vehicle.") 551-3. Other Articles. Wherever the requirements of other articles of this Code and Article 551 differ, the requirements of Article 551 shall apply. 551-4. General Requirements. (a) Not Covered. A recreational vehicle not used for the purposes as defined in Section 551-2 shall not be required to meet the provisions of Part A pertaining to the number or capacity of circuits required. It shall, however, meet all other applicable requirements of this article if the recreational vehicle is provided with an electrical installation intended to be energized from a 120- or 120/240-volt, nominal, ac power-supply system. (b) Systems. This article covers battery and direct-current power I (24-volts or less) systems, combination electrical systems, generator installations, and 120- or 120/240-volt, nominal, systems. B. Low-Voltage Systems 551-10. Low-Voltage Systems. (a) Low-Voltage Circuits. Low-voltage circuits furnished and installed by the recreational vehicle manufacturer, other than those related to braking and cranking/ignition, are 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) Copper conductors shall be used for low-voltage circuits. Exception: Metal chassis or frame shall be permitted as the return path to the source of supply. Connections to the chassis or frame shall be made (1) in an accessible location, (2) by means of copper conductors and copper or copper alloy terminals of the solderless type identified for the size of wire used, and (3) mechanically secure. (2) Conductors shall conform to the requirements for Type HDT, SGT, SGR, or Type SXL or shall have insulation in accordance with Table 310-13 or the equivalent. Conductor sizes No. 6 through 18 or SAE shall be listed. (FPN): See SAE Standard J1128-1975 for Types HDT and SXL and SAE Standard J1127-1980 for Types SGT and SGR. (3) Single-wire, low-voltage conductors shall be of the stranded type. (4) All insulated, low-voltage conductors shall be surface marked at intervals no greater than 4 feet (1.22 m) as follows: ARTICLE 551 - RECREATIONAL VEHICLES, PARKS 70-607 a. Listed conductors shall be marked as required by the listing agency. b. SAE conductors shall be marked with the name or logo of the manufacturer, specification designation, and wire gage. c. Other conductors shall be marked with the name or logo of the manufacturer, temperature rating, wire gage, conductor material, and insulation thickness. (c) Low-Voltage Wiring Methods. (1) 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 need not be so protected. Wiring shall be routed away from sharp edges, moving parts, or heat sources. (2) 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 SO spliced or joined as 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) Battery and direct-current circuits shall be physically separated by at least a 1/2-inch (12.7-mm) 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 terminals shall be accessible for service. The surface on which ground terminals make contact shall be cleaned and free from oxide or paint, or shall be electrically connected through use of a cadmium, tin, or zinc-plated internal-external toothed lockwasher or lockring 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 when attaching to aluminum structures. (5) The chassis-grounding terminal of the battery shall be bonded to the vehicle chassis with a minimum No. 8 copper conductor or equivalent. In the event the power lead from the battery exceeds No. 8, then the bonding conductor shall be of an equal size. (d) Battery Installations. Storage batteries subject to the provisions of this Code shall be securely attached to the vehicle and installed in an area vapor-tight to the interior and ventilated directly to the exterior of the vehicle. Where batteries are installed in a compartment, the compartment shall be ventilated with openings having a minimum area of 1.7 square inches (1100 sq mm) at both the top and at the bottom. Where compartment doors are equipped for ventilation, the openings shall be within 1 inch (25.4 mm) of the top and bottom. Batteries shall not be installed in a compartment containing spark- or flame-producing equipment, except that they shall be permitted to be installed in the engine generator compartment if the only charging source is from the engine generator. 70-608 NATIONAL ELECTRICAL CODE (e) Overcurrent Protection. (1) Low-voltage circuit wiring shall be protected by overcurrentprotective devices rated not in excess of the ampacity of copper conductors, as follows: 551-10(e)1 Wire Size 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) 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. (FPN): For further information, see Society of Automotive Engineers (SAE) Standard for Electric Fuses (Cartridge Type), ANSI/SAE J554(b)-1981; Standard for Blade Type Electric Fuses, SAE J1284; and Underwriters Laboratories Inc. Standard for Automotive Glass Tube Fuses, UL 275-1986. (3) Higher current-consuming, direct-current appliances such as pumps, compressors, heater blowers, and similar motor-driven appliances shall be installed in accordance with themanufacturer's instructions. Motors that are controlled by automatic switching or by latching-type manual switches shall be protected in accordance with Section 430-32(c). (4) The overcurrent-protective device shall be installed in an accessible location on the vehicle within 18 inches (457 mm) of the point where the power supply connects to the vehicle circuits. If located outside the recreational vehicle, the device shall be protected against weather and physical damage. Exception: External low-voltage supply shall be permitted to be fused within 18 inches (457 mm) after entering the vehicle or after leaving a metal raceway. (f) Switches. Switches shall have a direct-current rating not less than the connected load. (g) Lighting Fixtures. All low-voltage interior lighting fixtures shall be listed. Exception: Fixtures rated 4 watts or less, employing lamps rated 1.2 watts or less. (h) Cigarette Lighter Receptacles. Twelve-volt receptacles that will accept and energize cigarette lighters shall be installed in a noncombustible outlet box, or the assembly shall be identified by the manufacturer of the product as thermally protected. ARTICLE 551 - RECREATIONAL VEHICLES, PARKS 70-609 C. Combination Electrical Systems 551-20. Combination Electrical Systems. (a) General. Vehicle wiring suitable for connection to a battery or direct-current supply source shall be permitted to be connected to a 120- volt source, provided that the entire wiring system and equipment are rated and installed in full conformity with Parts A, C, D, E, and F requirements covering 120-volt electrical systems. Circuits fed from alternatingcurrent transformers shall not supply direct-current appliances. (b) Voltage Converters (120-Volt Alternating Current to Low-Voltage Direct Current). The 120-volt alternating current side of the voltage converter shall be wired in full conformity with Parts A, C, D, E, and F requirements for 120-volt electrical systems. Exception: Converters supplied as an integral part of a listed appliance shall not be subject to the above. All converters and transformers shall be listed for use in recreation vehicles and designed or equipped to provide over-temperature protection. To determine the converter rating, the following formula shall be applied to the total connected load, including average battery charging rate, of all 12-volt equipment: The first 20 amperes of load at 100 percent; plus The second 20 amperes of load at 50 percent; plus All load above 40 amperes at 25 percent. Exception: A low-voltage appliance that is controlled by a momentary switch (normally "open") that has no means for holding in the "closed" position shall not be considered as a "connected load" when determining the required converter rating. Momentarily energized appliances shall be limited to those used to prepare the vehicle for occupancy or travel. (c) Bonding Voltage Converter Enclosures. The noncurrent-carrying metal enclosure of the voltage converter shall be bonded to the frame of the vehicle with a No. 8 copper conductor minimum or equivalent. The grounding conductor for the battery and the metal enclosure shall be permitted to be the same conductor. (d) Dual-Voltage Fixtures or Appliances. Fixtures or appliances having both 120-volt and low-voltage connections shall be listed for dual voltage. (e) Autotransformers. Autotransformers shall not be used. (f) Receptacles and Plug Caps. Where a recreational vehicle is equipped with a 120-volt or 120/240-volt alternating-current system, a lowvoltage system, or both, receptacles and plug caps of the low-voltage system shall differ in configuration from those of the 120- or 120/240-volt system. Where a vehicle equipped with a battery or direct-current system has an external connection for low-voltage power, the connector shall have a configuration that will not accept 120-volt power. D. Other Power Sources 551-30. Generator Installations. (a) Mounting. Generators shall be mounted in such a manner as to be effectively bonded to the recreational vehicle chassis. 70-610 NATIONAL ELECTRICAL CODE (b) Generator Protection. Equipment shall be installed to ensure that the current-carrying conductors from the engine generator and from an outside source are not connected to a vehicle circuit at the same time. Receptacles used as disconnecting means shall be accessible (as applied to wiring methods) and capable of interrupting their rated current without hazard to the operator. (c) Installation of Storage Batteries and Generators. Storage batteries and internal-combustion-driven generator units (subject to the provisions of this Code) shall be secured in place to avoid displacement from vibration and road shock. (d) Ventilation of Generator Compartments. Compartments accommodating internal-combustion-driven generator units shall be provided with ventilation in accordance with instructions provided by the manufacturer of the generator unit. (FPN): For generator compartment construction requirements, see the Standard on Recreational Vehicles, NFPA 501C-1990. (e) Supply Conductors. The supply conductors from the engine generator to the first termination on the vehicle shall be of the stranded type and be installed in listed flexible conduit. The point of first termination shall be in a (1) panelboard, (2) junction box with a blank cover, (3) junction box with a receptacle, (4) enclosed transfer switch, or (5) receptacle assembly listed in conjunction with the generator. The panelboard or junction box with a receptacle shall be installed within the vehicle's interior and within 18 inches (457 mm) of the compartment wall but not inside the compartment. A junction box with a blank cover shall be mounted on the compartment wall and shall be permitted inside or outside the compartment. A receptacle assembly listed in conjunction with the generator shall be mounted in accordance with its listing. Overcurrent protection in accordance with Section 240-3 shall be provided for supply conductors as an integral part of a listed generator or shall be located within 18 inches (457 mm) of their point of entry into the vehicle. 551-31. Multiple Supply Source. (a) Multiple Supply Sources. Where a multiple supply system consisting of an alternate power source and a power-supply cord is installed, the feeder from the alternate power source shall be protected by an overcurrent-protective device. Installation shall be in accordance with Sections 551-30(a) and (b) and 551-40. (b) Calculation of Loads. Calculation of loads shall be in accordance with Section 551-42. (c) Multiple Supply Sources Capacity. The multiple supply sources shall not be required to be of the same capacity. (d) Alternate Power Sources Exceeding 30 Amperes. If an alternate power source exceeds 30 amperes, 120 volts, nominal, it shall be permissible to wire it as a 120-volt, nominal, system or a 120/240-volt, nominal, system, provided an overcurrent-protective device of the proper rating is installed in the feeder. ARTICLE 551 - RECREATIONAL VEHICLES, PARKS 70-611 (e) Power-Supply Assembly Not Less than 30 Amperes. The external power-supply assembly shall be permitted to be less than the calculated load but not less than 30 amperes and shall have overcurrent protection not greater than the capacity of the external power-supply assembly. 551-32. Other Sources. Other sources of ac power such as inverters or motor generators shall be listed for use in recreational vehicles and shall be installed in accordance with the terms of the listing. Other sources of ac power shall be wired in full conformity with the requirements in Parts A, C, D, E, and F of this article covering 120-volt electrical systems. 551-33. Alternate Source Restriction. Transfer equipment, if not integral with the listed power source, shall be installed to ensure that the currentcarrying conductors from other sources of ac power and from an outside source are not connected to the vehicle circuit at the same time. E. Nominal 120- or 120/240-Volt Systems 551-40. 120- or 120/240-Volt, Nominal, Systems. (a) General Requirements. The electrical equipment and material of recreational vehicles indicated for connection to a wiring system rated 120 volts, nominal, 2-wire with ground, or a wiring system rated 120/240 volts, nominal, 3-wire with ground, shall be listed and installed in accordance with the requirements of Parts A, C, D, E, and F. (b) Materials and Equipment. Electrical materials, devices, appliances, fittings, and other equipment installed, intended for use in, or attached to the recreational vehicle shall be listed. All products shall be used only in the manner in which they have been tested and found suitable for the intended use. (c) Ground-Fault Circuit-Interrupter Protection. The internal wiring of a recreational vehicle having only one 15- or 20-ampere branch circuit as permitted in Sections 551-42(a) and (b) shall have ground-fault circuitinterrupter protection for personnel. The ground-fault circuit-interrupter shall be installed at the point where the power supply assembly terminates within the recreational vehicle. Where a separable cord set is not employed, the ground-fault circuit-interrupter shall be permitted to be an integral part of the attachment plug of the power supply assembly. The ground-fault circuit-interrupter shall provide protection also under the conditions of an open grounded circuit conductor, interchanged circuit con- I ductors, or both. 551-41. Receptacle Outlets Required. (a) Spacing. Receptacle outlets shall be installed at wall spaces 2 feet (610 mm) wide or more so that no point along the floor line is more than 6 feet (1.83 m), measured horizontally, from an outlet in that space. Exception No. 1: Bath and hall areas. Exception No. 2: Wall spaces occupied by kitchen cabinets, wardrobe cabinets, built-in furniture, behind doors that may open fully against a wall surface, or similar facilities. 70-612 NATIONAL ELECTRICAL CODE (b) Location. Receptacle outlets shall be installed: (1) Adjacent to counter tops in the kitchen [at least one on each side of the sink if counter tops are on each side and are 12 inches (305 mm) or over in width]. (2) Adjacent to the refrigerator and gas range space, except where a gas-fired refrigerator or cooking appliance, requiring no external electrical connection, is factory-installed. (3) Adjacent to counter top spaces of 12 inches (305 mm) or more in width that cannot be reached from a receptacle required in Section 551- 41(b)(1) by a cord of 6 feet (1.83 m) without crossing a traffic area, cooking appliance, or sink. (c) Ground-Fault Circuit-Interrupter Protection. Where provided, each 120-volt, single-phase, 15- or 20-ampere receptacle outlet shall have ground-fault circuit-interrupter protection for personnel in the following locations: (1) Adjacent to a bathroom lavatory. [The receptacle outlet shall be a minimum of 24 inches (610 mm) from the compartment floor.] (2) Within 6 feet (1.83 m) of any lavatory or sink. Exception: Receptacles installed for appliances in dedicated spaces, such as for dishwashers, disposals, refrigerators, freezers, and laundry equipment. (3) In the area occupied by a toilet, shower, tub, or any combination thereof. (4) On the exterior of the vehicle. Exception: Receptacles that are located inside of an access panel that is installed on the exterior of the vehicle to supply power for an installed appliance shall not be required to have ground-fault circuit-interrupter protection. The receptacle outlet shall be permitted in a listed lighting fixture. A receptacle outlet shall not be installed in a tub or combination tub-shower compartment. Exception: Where ground-fault circuit-interrupter protection is provided in accordance with Section 551-40(c). (d) Face-Up Position. A receptacle shall not be installed in a face-up position in any counter top or similar horizontal surfaces within the living area. 551-42. Branch Circuits Required. Each recreational vehicle containing a 120-volt electrical system shall contain one of the following: (a) One 15-Ampere Circuit. One 15-ampere circuit to supply lights, receptacle outlets, and fixed appliances. Such recreational vehicles shall be equipped with one 15-ampere switch and fuse or 15-ampere circuit breaker. (b) One 20-Ampere Circuit. One 20-ampere circuit to supply lights, receptacle outlets, and fixed appliances. Such recreational vehicles shall be equipped with one 20-ampere switch and fuse or 20-ampere circuit breaker. ARTICLE 551 - RECREATIONAL VEHICLES, PARKS 70-613 (c) Two or More 15- or 20-Ampere Circuits. Two or more 15- or 20-ampere circuits to supply lights, receptacle outlets, and fixed appliances. Such recreational vehicles shall be equipped with a 30-ampere rated main power supply assembly. (FPN): See Section 210-23(a) for permissible loads. See Section 551-45(c) for main disconnect and overcurrent protection requirements. (d) Power-Supply Assembly. A 40- or 50-ampere power-supply assembly that shall be calculated in accordance with the following method: (1) Lighting. If electric lighting is provided either directly or indirectly (through a voltage converter) by the 120-volt or 120/240-volt system, calculate lighting wattage at 3 volt-amperes per square foot using exterior dimensions (exclusive of hitch and cab) as follows: Length (feet) X width (feet) X 3 = lighting volt-amperes. (2) Small Appliance. Number of circuits times 1,500 volt-amperes for each 20-ampere appliance receptacle circuit, e.g., Number of Circuits X 1,500 = small appliance volt-amperes. (3) Total. Lighting volt-amperes plus small appliance volt-amperes = total volt-amperes. (4) First 3,000 total volt-amperes at 100 percent plus remainder at 35 percent = volt-amperes to be divided by voltage to obtain current (amperes) per leg. Amperes per Leg A B Lighting and small appliance current (amperes) per leg [from (d) above] = (5) Add nameplate amperes for motors and heater loads (exhaust fans, air conditioners,* electric, gas, or oil heating*). Also include anticipated loads in above categories where prewired outlets or circuits are installed for other than factory-installed major appliances. *Omit smaller of heating or air-conditioning load, except include any motor common to both functions. (6) Add 25 percent of amperes of largest motor in E = (7) Add nameplate amperes of the following appliances. Include anticipated loads where prewired outlets or circuits are installed for other than factory-installed major appliances. Where the number of appliances is four or more, use 75 percent of total. Disposal Water Heater Wall-Mounted Ovens Cooking Units TOTAL = 70-614 NATIONAL ELECTRICAL CODE (8) Add amperes for freestanding range as distinguished from separate ovens and cooking units. Derive from following table by dividing voltamperes by 240 volts. 551-42(8) Nameplate Use Range Rating (watts) (volt-amperes) (Freestanding range as 0 thru 10,000 80 percent of rating distinguished from Over 10,000 thru 12,500 8,000 separate oven and Over 12,500 thru 13,500 8,400 cooking units Over 13,500 thru 14,500 8,800 Over 14,500 thru 15,500 9,200 Over 15,500 thru 16,500 9,600 Over 16,500 thru 17,500 10,000 551-43. Branch-Circuit Protection. (a) Rating. The branch-circuit overcurrent devices shall be rated: (1) Not more than the circuit conductors; and (2) Not more than 150 percent of the rating of a single appliance rated 13.3 amperes or more and supplied by an individual branch circuit; but (3) Not more than the overcurrent protection size marked on an air conditioner or other motor-operated appliances. (b) Protection for Smaller Conductors. A 20-ampere fuse or circuit breaker shall be permitted for protection for fixture leads, cords, or small appliances, and No. 14 tap conductors, not over 6 feet (1.83 m) long for recessed lighting fixtures. (c) 15-Ampere Receptacle Considered Protected by 20 Amperes. If more than one outlet or load is on a branch circuit, a 15-ampere receptacle shall be permitted to be protected by a 20-ampere fuse or circuit breaker. 551-44. Power-Supply Assembly. (a) 15-Ampere Main Power-Supply Assembly. Recreational vehicles wired in accordance with Section 551-42(a) shall use a listed 15-ampere, or larger, main power-supply assembly. (b) 20-Ampere Main Power-Supply Assembly. Recreational vehicles wired in accordance with Section 551-42(b) shall use a listed 20-ampere, or larger, main power-supply assembly. (c) 30-Ampere Main Power-Supply Assembly. Recreational vehicles wired in accordance with Section 551-42(c) shall use a listed 30-ampere, or larger, main power-supply assembly. (d) 40- or 50-Ampere Power-Supply Assembly. In accordance with Section 551-42(d), any recreational vehicle with a rating in excess of 30 amperes, 120 volts, shall use a listed 40-ampere or 50-ampere, 120/240-volt power-supply assembly. ARTICLE 551 - RECREATIONAL VEHICLES, PARKS 70-615 Exception No. 1: Where the calculated load of the recreational vehicle exceeds 30 amperes, 120 volts, a second power-supply cord shall be permitted. Where a two-cord supply system is installed, they shall not be interconnected on either the line side or the load side. The grounding circuits and grounding means shall be electrically interconnected. Exception No. 2: For a dual-supply source consisting of a generator and a power-supply cord, see Section 551-31. 551-45. Distribution Panelboard. (a) Listed and Appropriately Rated. A listed and appropriately rated distribution panelboard or other equipment specifically listed for the purpose shall be used. The grounded conductor termination bar shall be insulated from the enclosure as provided in Section 551-54(c). An equipment grounding terminal bar shall be attached inside the metal enclosure of the panelboard. (b) Location. The distribution panelboard shall be installed in a readily accessible location. Working clearance for the panelboard shall be no less than 24 inches (610 mm) wide and 30 inches (762 mm) deep. Exception No. 1: Where the panelboard cover is exposed to the inside aisle space, then one of the working clearance dimensions shall be permitted to be reduced to a minimum of 22 inches (559 mm). A panelboard is considered exposed where the panelboard cover is within 2 inches (50.8 mm) of the aisle's finished surface. Exception No. 2: Compartment doors used for access to a generator shall be permitted to be equipped with a locking system. (c) Dead-Front Type. The distribution panelboard shall be of the deadfront type and shall consist of one or more circuit breakers or Type S fuseholders. A main disconnecting means shall be provided where fuses are used or where more than two circuit breakers are employed. A main overcurrent protective device not exceeding the power-supply assembly rating shall be provided where more than two branch circuits are employed. 551-46. Means for Connecting to Power Supply. (a) Assembly. The power-supply assembly or assemblies shall be factory-supplied or factory-installed and be of one of the types as specified herein: (1) Separable. Where a separable power-supply assembly consisting of a cord with a female connector and molded attachment plug cap is provided, the vehicle shall be equipped with a permanently mounted, flanged surface inlet (male, recessed-type motor-base attachment plug) wired directly to the distribution panelboard by an approved wiring method. The attachment plug cap shall be of a listed type. (2) Permanently Connected. Each power-supply assembly shall be connected directly to the terminals of the distribution panelboard or conductors within a junction box and provided with means to prevent strain from being transmitted to the terminals. The ampacity of the conductors between each junction box and the terminals of each distribution panelboard shall be at least equal to the ampacity of the power-supply cord. The 70-616 NATIONAL ELECTRICAL CODE supply end of the assembly shall be equipped with an attachment plug of the type described in Section 551-46(c). Where the cord passes through the walls or floors, it shall be protected by means of conduit and bushings or equivalent. The cord assembly shall have permanent provisions for protection against corrosion and mechanical damage while the vehicle is in transit. (b) Cord. The cord exposed usable length shall be measured from the point of entrance to the recreational vehicle or the face of the flanged surface inlet (motor-base attachment plug) to the face of the attachment plug at the supply end. The cord exposed usable length, measured to the point of entry on the vehicle exterior, shall be a minimum of 23 feet (7.0 m) where the point of entrance is at the side of the vehicle, or shall be a minimum 28 feet (8.5 m) where the point of entrance is at the rear of the vehicle. Where the cord entrance into the vehicle is more than 3 feet (0.9 m) above the ground, the minimum cord lengths above shall be increased by the vertical distance of the cord entrance heights above 3 feet (0.9 m). (FPN): See Section 551-46(e). (c) Attachment Plugs. (1) Recreational vehicles having only one 15-ampere branch circuit as I permitted by Section 551-42(a) shall have an attachment plug that shall be 2-pole, 3-wire, grounding type, rated 15 amperes, 125 volts, conforming to the configuration shown in Figure 551-46(c). (FPN): Complete details of this configuration can be found in American National Standard ANSI C73.11-1972. (2) Recreational vehicles having only one 20-ampere branch circuit as permitted in Section 551-42(b) shall have an attachment plug that shall be 2-pole, 3-wire, grounding type, rated 20 amperes, 125 volts, conforming to the configuration shown in Figure 551-46(c). (FPN): Complete details of this configuration can be found in American National Standard ANSI C73.12-1972. (3) Recreational vehicles wired in accordance with Section 551-42(c) shall have an attachment plug that shall be 2-pole, 3-wire, grounding type, rated 30 amperes, 125 volts, conforming to the configuration shown in Figure 551-46(c) intended for use with units rated at 30 amperes, 125 volts. (FPN): Complete details of this configuration can be found in American National Standard Dimensions of Caps, Plugs and Receptacles, ANSI C73.13-1972. (4) Recreational vehicles having a power-supply assembly rated 40 amperes or 50 amperes as permitted by Section 551-42(d) shall have a 3-pole, 4-wire, grounding-type attachment plug rated 50 amperes, 125/250 volts, conforming to the configuration shown in Figure 551-46(c). (FPN): Complete details of this configuration can be found in American National Standard Dimensions of Caps, Plugs and Receptacles, ANSI C73.17-1972. (d) Labeling at Electrical Entrance. Each recreational vehicle shall have permanently affixed to the exterior skin, at or near the point of entrance of the power-supply cord(s), a label 3 inches (76 mm) by 13/4 inches (44.5 mm) minimum size, made of etched, metal-stamped or embossed brass, stainless steel, or anodized or alclad aluminum not less than 0.020 inch ARTICLE 551 - RECREATIONAL VEHICLES, PARKS 70-617 Receptacles Caps G 125-volt, 20-amp, W 2-pole, 3-wire, grounding type OG 20 amp I H W G 125-volt, 15-amp, W 2-pole, 3-wire, grounding type 125-volt, 2-pole, 3-wire, grounding type G G 30 amp I W W 125-volt, 2-pole, 3-wire, grounding type G G 50 amp Y[] X X Y I W W 125/250-volt, 3-pole, 4-wire, grounding type Figure 551-46(c). Configurations for Grounding-type Receptacles and Attachment Plug Caps Used for Recreational Vehicle Supply Cords and Recreatonal Vehicle Lots. (508 micrometers) thick, or other suitable material [e.g., 0.005-inch (127-micrometer) thick plastic laminate], that reads, as appropriate, either: "This connection is for 110-125 volt ac, 60 Hz ampere supply," or "This connection is for 120/240 volt ac, 3-pole, 4-wire 60 Hz ampere supply." The correct ampere rating shall be marked in the blank space. (e) Location. The point of entrance of a power-supply assembly shall be located within 15 feet (4.57 m) of the rear, on the left (road) side or at the rear, left of the longitudinal center of the vehicle, within 18 inches (457 mm) of the outside wall. Exception No. 1: A recreational vehicle equipped with only a listed flex- I ible drain system or a side-vent drain system shall be permitted to have the electrical point of entrance located on either side, provided the drain(s) for the plumbing system is (are) located on the same side. Exception No. 2: A recreational vehicle shall be permitted to have the electrical point of entrance located more than 15 feet (4.57 m) from the 70-618 NATIONAL ELECTRICAL CODE rear. Where this occurs, the distance beyond the 15-foot (4.57-m) dimension shall be added to the cord's minimum length as specified in 551-46(b). 551-47. Wiring Methods. (a) Wiring Systems. Rigid metal conduit, intermediate metal conduit, electrical metallic tubing, rigid nonmetallic conduit, flexible metal conduit, Type MC cable, Type MI cable, Type AC cable, and nonmetallic-sheathed cable shall be permitted. An equipment grounding means shall be provided in accordance with Section 250-91. (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) Nonmetallic Boxes. Nonmetallic boxes shall be acceptable only with nonmetallic-sheathed cable or rigid nonmetallic conduit. (d) 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. (e) Mounting. Wall and ceiling boxes shall be mounted in accordance with Article 370. 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 1¹/2-inch (38-mm) minimum width backing around the box and of a thickness of ¹/₂ inch (12.7 mm) or greater (actual) glued to the wall panel shall be considered as approved means for mounting outlet boxes. (f) Sheath Armor. The sheath of nonmetallic-sheathed cable, metal-clad cable, and Type AC cable shall be continuous between outlet boxes and other enclosures. (g) Protected. Metal-clad, Type AC, or nonmetallic-sheathed cables shall be permitted to pass through the centers of the wide side of 2-inch by 4-inch wood studs. However, they shall be protected where they pass through 2-inch by 2-inch wood studs or at other wood studs or frames where the cable would be less than 1½ inches (38 mm) from the inside or outside surface. Steel plates on each side of the cable, or a steel tube, with not less than No. 16 MSG wall thickness, shall be installed to protect the cable. These plates or tubes shall be securely held in place. Where nonmetallic-sheathed cables pass through punched, cut, or drilled slots or holes in metal members, the cable shall be protected by bushings or grommets securely fastened in the opening prior to installation of the cable. (h) Bends. No bend shall have a radius of less than five times the cable diameter. (i) Cable Supports. Where connected with cable connectors or clamps, cables shall be supported within 12 inches (305 mm) of outlet boxes, distribution panelboards, and splice boxes on appliances. Supports shall be provided every 4½ feet (1.37 m) at other places. ARTICLE 551 - RECREATIONAL VEHICLES, PARKS 70-619 (j) Nonmetallic Box Without Cable Clamps. Nonmetallic-sheathed cables shall be supported within 8 inches (203 mm) of a nonmetallic outlet box without cable clamps. Exception: Where wiring devices with integral enclosures are employed with a loop of extra cable to permit future replacement of the device, the cable loop shall be considered as an integral portion of the device. (k) Physical Damage. Where subject to physical damage, exposed nonmetallic cable shall be protected by covering boards, guard strips, raceways, or other means. (I) Metal Faceplates. Metal faceplates shall be of ferrous metal not less than 0.030 inch (762 micrometers) in thickness or of nonferrous metal not less than 0.040 inch (1.02 mm) in thickness. Nonmetallic faceplates shall be listed. (m) Metal Faceplates Effectively Grounded. Where metal faceplates are used, they shall be effectively grounded. (n) Moisture or Physical Damage. Where outdoor or underchassis wiring is 120 volts, nominal, or over and is exposed to moisture or physical damage, the wiring shall be protected by rigid metal conduit, intermediate metal conduit, or by electrical metallic tubing or rigid nonmetallic conduit that is closely routed against frames and equipment enclosures or other raceway or cable identified for the application. (o) 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, fault-current withstanding, and shall be capable of enduring the vibration and shock occurring in recreational vehicles. (p) Method of Connecting Expandable Units. (1) 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 conform to all provisions of Article 400 and shall be considered as a permitted use under