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(continued)
(j) Testing for leakage. Before setting the system in operation, tank installations and piping shall be checked for oil leaks with fuel oil of the same grade that will be burned in the appliance. No other material shall be used for testing oil tanks and piping. Tanks shall be filled to maximum capacity for the final check for oil leakage.
280.707. Heat Producing Appliances.
(a) Heat-producing appliances and vents, roof jacks and chimneys necessary for their installation in mobile homes shall be listed or certified by a nationally recognized testing agency for use in mobile homes.
(1) A mobile home shall be provided with a comfort heating system. (i) When a mobile home is manufactured to contain a heating appliance, the heating appliance shall be installed by the manufacturer of the mobile home in compliance with applicable sections of this subpart. (ii) When a mobile home is manufactured for field application of an external heating or combination heating/cooling appliance, preparation of the mobile home for this external application shall comply with the applicable sections of this part.

(2) After the effective date specified herein gas and oil burning comfort heating appliances shall have a flue loss of not more than that specified below, and a thermal efficiency of not less than that specified in nationally recognized standards. (See 280.703)

Maximum allowable
Effective date: flue loss
Jan. 1, 1977 25 percent
Jan. 1, 1976 30 percent


(b) Fuel-burning heat-producing appliances and refrigeration appliances, except ranges and ovens, shall be of the vented type and vented to the outside.
(c) Fuel-burning appliances shall not be converted from one fuel to another fuel unless converted in accordance with the terms of their listing and the appliance manufacturer's instructions.
(d) Performance Efficiency.

(1) All automatic electric storage water heats shall have a standby loss not exceeding 443 watts/meter<>2 (4 watts/Ft 2) of tank surface area effective January 1, 1977. The method of test for standby loss shall be as described in Section 4.3.1. of ANSI C72.1-72.
(2) All gas and oil-fired automatic storage water heaters shall have a recovery efficiency, E, and a standby loss, S, as described below, effective January 1, 1977. The method of test of E, and S shall be as described in Section 2.7 of ANSI Z21.10.1-1974, except that for oil-fired units, CF=1.0, Q=total gallons of oil consumed and H=total heating value of oil in Btu/gallon.

Storage capacity Recovery Standby Loss
in gallons efficiency
Less than 25 At least 75 percent Not more than 7.5 percent
25 up to 35 do Not more than 7 percent
35 or more do Not more than 8 percent


(e) Each space heating, cooling or combination heating and cooling system shall be provided with at least one readily adjustable automatic control for regulation of living space temperature. The controll shall be placed a minimum of 3 feet from the vertical edge of the appliance compartment door. It shall be located on an exterior wall or on a wall separating the appliance compartment from a habitable room.
280.708.
(a) Clothes dryers.
(1) Clothes dryers shall be exhausted to the outside by a moisture-lint exhaust duct and termination fitting. Such termination fittings for gas dryers shall be listed or certified as components of the dryer.
(2) A clothes dryer moisture-lint exhaust duct shall not be connected to any other duct, vent or chimney.
(3) The exhaust duct shall not terminate beneath the mobile home.
(4) Moisture-lint exhaust ducts shall not be connected with sheet metal screws or other fastening devices which extend into the interior of the duct.

(b) Gas clothes dryer. A mobile home may be provided with 'stubbed in' equipment at the factory to supply a gas clothes dryer for future installation by the owner provided it complies with the following provisions:
(1) The 'stubbed in' gas outlet shall be provided with a shutoff valve, the outlet of which is closed by threaded pipe plug or cap.
(2) The 'stubbed in' gas outlet shall be permanently labeled to identify it for use only as the supply connection for a gas clothes dryer.
(3) A moisture-lint exhaust duct system shall be roughed in by the manufacturer at the time of original installation. The moisture-lint exhaust system shall comply with provisions of 280.708(a)(1) through (4).
(c) Electric clothes dryers. Electric clothes dryers shall be exhausted to the outside in accordance with the appliance manufacturer's instructions. When a receptacle is installed to supply an electric clothes dryer for future installation by the owner, the moisture-lint exhaust system shall comply with provisions of 280.708(a)(1) through (4).
280.709. Installation of Appliances.
(a) The installation of each appliance shall conform to the terms of its listing and the manufacturer's instructions. The installer shall leave the manufacturer's instructions attached to the appliance. Every appliance shall be secured in place to avoid displacement. For the purpose of servicing and replacement, each appliance shall be both accessible and removable.
(b) Heat-appliances shall be so located that no doors, drapes, or other such material can be placed or/swing closer to the front of the appliance than the clearances specified on the labeled appliances.
(c) Clearances between heat-producing appliances and adjacent surfaces shall not be less than specified in the terms of their listing. Clearance spaces shall be framed in or guarded to prevent creation of storage space within the clearance specified.
(d) All fuel-burning appliances, except ranges, ovens, illuminating appliances, clothes dryers, solid fuel-burning fireplaces and solid fuel-burning fireplace stoves, shall be installed to provide for the complete separation of the combustion system from the interior atmosphere of the mobile home. Combustion air inlets and flue gas outlets shall be listed or certified as components of the appliance. The required separation may be obtained by:
(1) The installation of direct vent system (sealed combustion system) appliance, or
(2) The installation of appliances within enclosures so as to separate the appliance combustion system and venting system from the interior atmosphere of the mobile home. There shall be any door, removable access panel, or other opening into the enclosure from the inside of the mobile home. Any opening for ducts, piping, wiring, etc., shall be sealed.
(e) A forced air appliance and its return-air system shall be designed and installed so that negative pressure created by the air-circulating fan cannot affect its or another appliance's combustion air supply or act to mix products of combustion with circulation air.
(1) The air circulating fan or a furnace installed in an enclosure with another fuel-burning appliance shall be operable only when any door or panel covering an opening in the furnace fan compartment or in a return air plenum or duct is in the closed position. This does not apply if both appliances are direct vent system (sealed combustion system) appliances.
(2) If a warm air appliance is installed within an enclosure to conform to 280.709(d)(2), each warm-air outlet and each return air inlet shall extend to the exterior of the enclosure. Ducts, if used for that purpose, shall not have any opening within the enclosure and shall terminate at a location exterior to the enclosure.
(3) Cooling coils installed as a portion of, or in connection with, any forced-air furnace shall be installed on the downstream side unless the furnace is specially otherwise listed.
(4) An air conditioner evaporator section shall not be located in the air discharge duct or plenum of any forced-air furnace unless the mobile home manufacturer has complied with certification required in 280.511.
(5) If a cooling coil is installed with a forced-air furnace, the coil shall be installed in accordance with its listing. When a furnace-coil unit has a limited listing, the installation must be in accordance with that listing.
(6) When an external heating appliance or combination cooling/heating appliance is to be applied to a mobile home, the manufacturer shall make provision for proper location of the connection to the mobile home supply system and return air system of the external ducts connected to the appliance.
(7) The installation of a self contained air conditioner comfort cooling appliance shall meet the following requirements: (i) The installation on a duct common with an installed heating appliance shall require the installation of an automatic damper or other means to prevent the cooled air from passing through the heating appliance unless the heating appliance is certified or listed for such application and the supply system is intended for such an application. (ii) The installation shall prevent the flow of heated air into the external cooling appliance and its connecting ducts to the mobile home supply and return air system during the operation of the heating appliance installed in the mobile home. (iii) The installation shall prevent simultaneous operation of the heating and cooling appliances.
(f) Vertical clearance above cooking top. Ranges shall have a vertical clearance above the cooking top of not less than 24 inches. (see 280.204)
(g) Solid fuel-burning factory-built fireplaces and fireplace stoves listed for use in mobile homes may be installed in mobile homes provided they and their installation conform to the following paragraphs. A fireplace or fireplace stove shall not be considered as a heating facility for determining compliance with Subpart F.
(1) A solid fuel-burning fireplace or fireplace stove shall be equipped with integral door(s) or shutter(s) designed to close the fireplace or fireplace stove fire chamber opening and shall include complete means for venting through the roof, a combustion air inlet, a hearth extension, and means to securely attach the fireplace or the fireplace stove to the mobile home structure. The installation shall conform to the following paragraphs (g)(1)(i) to (vii) inclusive: (i) A listed factory-built chimney designed to be attached directly to the fireplace or fireplace stove shall be used. The listed factory built chimney shall be equipped with and contain as of of its listing a termination device(s) and a spark arrester(s). (ii) A fireplace or fireplace stove, air intake assembly, hearth extension and the chimney shall be installed in accordance with the terms of their listings and their manufacturer's instructions. (iii) The combustion air inlet shall conduct the air directly into the fire chamber and shall be designed to prevent material from the hearth dropping onto the area beneath the mobile home. (iv) The fireplace or fireplace stove shall not be installed in a sleeping room. (v) Hearth extension shall be of noncombutible material not less than 3/8-inch thick. The hearth shall extend at least 16 inches in front of and at least 8 inches beyond each side of the fireplace or fireplace stove opening. Furthermore the hearth shall extend over the entire surface beneath a fireplace stove and beneath an elevated or overhanging fireplace. (vi) The label on each solid fuel-burning fireplace and solid fuel-burning fireplace stove shall include the following wording: For use with solid fuel only. (vii) The chimney shall extend at least three feet above the part of the roof through which it passes and at least two feet above the highest elevation of any part of the mobile home within 10 feet of the chimney. Portions of the chimney and termination that exceed an elevation of 13-1/2 ft. above ground level may be designed to be removed for transporting the mobile home.
280.710. Venting, Ventilation and Combustion Air.
(a) The venting as required by 280.707(b) shall be accomplished by one or more of the methods given in (1) and (2) below:
(1) An integral venting system listed or certified as part of the appliance.
(2) A venting system consisting entirely of listed components, including roof jack, installed in accordance with the terms of the appliance listed and the appliance manufacturer's instructions.
(b) Venting and combustion air systems shall be installed in accordance with the following:
(1) Component shall be securely assembled and properly aligned using the method shown in the appliance manufacturer's instructions.
(2) Draft hood connectors shall be firmly attached to draft hood outlets or flue collars by sheet metal screws or by equivalent effective mechanical fasteners.
(3) Every joint of a vent, vent connector, exhaust duct and combustion air intake shall be secure and in alignment.
(c) Venting systems shall not terminate underneath a mobile home.
(d) Venting system terminations shall be not less than three feet from any motor-driven air intake discharging into habitable areas.
(e) The area in which cooking appliances are located shall be ventilated by a metal duct which may be single wall, not less than 12.5 square inches in cross-sectional area (minimum dimension shall be two inches) located above the appliance(s) and terminating outside the mobile home, or by listed mechanical ventilating equipment discharging outside the home, that is installed in accordance with the terms of listing and the manufacturer's instructions. Gravity or mechanical ventilation shall be installed with a horizontal distance of not more than ten feet from the vertical front of the appliance(s).
(f)Mechanical ventilation which exhausts directly to the outside atmosphere from the living space of a home shall be equipped with an automatic or manual damper. Operating controls shall be provided such that mechanical ventilation can be separately operated without directly energizing other energy consuming devices.
280.711. Instructions.
Operating instructions shall be provided with each appliance. These instructions shall include directions and information covering the proper use and efficient operation of the appliance and its proper maintenance.
280.712. Marking.

(a) Information on clearances, input rating, lighting and shutdown shall be attached to the appliances with the same permanence as the nameplate, and so located that it is easily readable when the appliance is properly installed or shutdown for transporting of mobile home.
(b) Each fuel-burning appliance shall bear permanent marking designating the type(s) of fuel for which it is listed.
280.713. Accessibility.
Every appliance shall be accessible for inspection, service, repair, and replacement without removing permanent construction. Sufficient room shall be available to enable the operator to observe the burner, control, and ignition means while starting the appliance.
280.714. Appliances, Cooling.
(a) Every air conditioning unit or a combination air conditioning and heating unit shall be listed or certified by a nationally recognized testing agency for the application for which the unit is intended and installed in accordance with the terms of its listing.
(1) Mechanical air conditioners shall be rated in accordance with the Standard for Unitary Air-Conditioning Equipment (ARI Standard 210-74) and certified by ARI or other nationally recognized testing agency capable of providing follow-up service. (i) Electric motor-driven unitary cooling systems with rated capacity less than 65,000 Btu/hr. manufactured after the times indicated in the following table, when rated at ARI Standard rating conditions as listed in ARI Standard 210-74, shall show energy efficiency ratio (EER) values not less than as shown below:

Energy
effeciency
Date: ratio
Jan. 1, 1977 6.5
Jan. 1, 1980 7.2


(ii) Direct refrigerating systems serving any air conditioner or comfort-cooling system installed that ranks no lower than Group 5 in the Underwriters' Laboratories, Inc. 'Classification of Comparative Life Hazard of Various Chemicals.' (iii) Heat pumps shall be listed in the ARI Directory of Certified Unitary Heat Pumps or certified to comply with all the requirements of the Standard for Unitary Heat Pumps 240-74. Electric motor-driven vapor compression heat pumps with supplemental electrical resistance heat shall be sized to provide by compression at least 60 percent of the calculated annual heating requirement for the mobile home being served. A controll shall be provided and set to prevent operation of supplemental electrical resistance heat at outdoor temperatures above 40° F. except for defrost operation. (iv) Electric motor-driven vapor compression heat pumps with supplemental electric resistance heat conforming to ARI Standard 240-74 manufactured after the dates indicated in the table shall show coefficient of performance ratios not less than shown below:

COP
Outdoor air temperature
Date
45° F 20° F 0° F
Jan. 1, 1977 2.2 1.4 Permit shutoff.
Jan. 1, 1980 2.5 1.7 1.0.



(2) Gas fired absorption air conditioners shall be listed or certified in accordance with ANSI Standard Z21.40.1-1973 and certified by AGA or another nationally recognized testing agency capable of providing follow-up service.
(3) Direct refrigerating systems servicing any air conditioning or comfort-cooling system installed in a mobile home shall employ a type of refrigerant that ranks no lower than Group 5 in the Underwriters' Laboratories, Inc. 'Classification of Comparative Life Hazard of Various Chemical.'
(b) Installation and instructions.
(1) The installation of each appliance shall conform to the terms of its listing as specified on the appliance and in the manufacturer's installation instructions. The installer shall include the manufacturer's instructions in the mobile home. Appliances shall be secured in place to avoid displacement and movement from vibration and road shock.
(2) Operating instructions shall be provided with the appliance.

(c) Fuel-burning air conditioners shall also comply with 280.707.
(d) The appliance rating plate shall be so located that it is easily readable when the appliance is properly installed.
(e) Every installed appliance shall be accessible for inspection, service, repair and replacement without removing permanent construction.
280.715. Circulating Air System.
(a) Supply system.
(1) Supply ducts and any dampers contained therein shall be made from galvanized steel, tinplated steel, or aluminum, or shall be listed Class 0, Class 1, or Class 2 air ducts. Class 2 air ducts shall be located at least 3 feet from the furnace bonnet or plenum. A duct system integral with the structure shall be of durable construction that can be demonstrated to be equally resistant to fire and deterioration. Ducts constructed from sheet metal shall be in accordance with the following table:
Minimum metal thickness for ducts [FN1]


Diameter Width
Duct type 14 in over
or less 14 in
Round 0.013 0.016
Enclosed rectangular .01 .016
Exposed rectangular .016 .019
FN1 When 'nominal' thickness are specified, 0.003 in. shall be added to these
'minimum' metal thicknesses.


(2) Sizing of ducts for heating. (i) Ducts shall be so designed that when a labelled forced-air furnace is installed and operated continuously at its normal heating air circulating rate in the mobile home, with all registers in the full open position, the static pressure measured in the casing shall not exceed 90% of that shown on the label of the appliance. For upflow furnaces the static pressure shall be taken in the duct plenum. For external heating or combination heating/cooling appliances the static pressure shall be taken at the point used by the agency listing or certifying the appliance. (ii) When an evaporator-coil specifically designed for the particular furnace is installed between the furnace and the duct plenum, the total static pressure shall be measured downstream of the coil in accordance with the appliance label and shall not exceed 90 percent of that shown on the label of the appliance. (iii) When any other listed air-cooler coil is installed between the furnace and the duct plenum, the total static pressure shall be measured between the furnace and the coil and it shall not exceed 90 percent of that shown on the label of the furnace. (iv) The minimum dimension of any branch duct shall be at least 1- 1/2 inches, and of any main ducts, 2-1/2 inches.
(3) Sizing of ducts for air cooling. (i) The mobile home manufacturer shall certify the capacity of the air cooling supply duct system for the maximum allowable output of ARI certified central air conditioning systems. The certification shall be at operating static pressure of 0.3 inches of water or greater (see 280.511). (ii) The refrigerated air cooling supply duct system including registers must be capable of handling at least 300 CFM per 10,000 btuh with a static pressure no greater than 0.3 inches of water when measured at room temperature. In the case of application of external self-contained comfort cooling appliances or the cooling mode of combination heating/cooling appliances, either the external ducts between the appliance and the mobile home supply system shall be considered part of, and shall comply with the requirements for the refrigerated air cooling supply duct system, or the connecting duct between the external appliance and the mobile home supply duct system shall be a part of the listed appliance. The minimum dimension of any branch duct shall be at least 1-1/2 inches, and of any main duct, 2-1/2 inches.
(4) Airtightness of supply duct systems. A supply duct system shall be considered substantially airtight when the static pressure in the duct system, with all registers sealed and with the furnace air circulator at high speed, is at least 80 percent of the static pressure measured in the furnace casing,w ith its outlets sealed and the furnace air circulator operating at high speed. For the purpose of this paragraph and 280.715(b) pressures shall be measured with a water manometer or equivalent device calibrated to read in increments not greater than 1/10 inch water column.
(5) Expandable or multiple home connections. (i) An expandable or multiple mobile home may have ducts of the heating system installed in the various units. The points of connection must be so designed and constructed that when the mobile home is fully expanded or coupled, the resulting duct joint will conform to the requirements of this Part. (ii) Installation instructions for supporting the cross-over duct from the mobile home shall be provided for onsite installation. The duct shall not be in contact with the ground.

(6) Air supply ducts shall be insulated with material having an effective thermal resistance (R) of not less than 4.0 unless they are within mobile home insulation having a minimum effective value of R-4.0 for floors or R-6.0 for ceilings.
(7) Supply and return ducts exposed directly to outside air, such as under chassis crossover ducts connecting external heating, cooling or combination heating/cooling appliances shall be insulated with material having a minimum thermal resistance of R-4.0 with a continuous vapor barrier having a perm rating of not more than 1 perm. Where exposed underneath the mobile home, all such ducts shall comply with 280.715(a)(5)(ii).
(b) Return air systems.
(1) Return air openings. Provisions shall be made to permit the return of circulating air from all rooms and living spaces, except toilet room(s), to the circulating air supply inlet of the furnace.
(2) Duct Material. Return ducts and any diverting dampers contained therein shall be in accordance with the following: (i) Portions of return ducts dirrectly above the heating surfaces or closer than 2 feet from the outer jacket or casing of the furnace shall be constructed of metal in accordance with 280.715(a)(1) or shall be listed Class 0 or Class 1 air ducts. (ii) Return ducts, except as required by (a) above, shall be constructed of on-inch (nominal) wood boards (flame spread classification of not more than 200), other suitable material no more flammable than one-inch board or in accordance with 280.715(a)(1). (ii) The interior of combustible2 ducts shall be lined with noncombustible material at points where there might be danger from incandescent particles dropped through the register or furnace such as directly under floor registers and the bottom return. (iv) Factory made air ducts used for connecting external heating, cooling or combination heating/cooling appliances to the supply system and return air system of a mobile home shall be listed by a nationally recognized testing agency. Ducts applied to external heating appliances or combination heating/cooling appliances supply system outlets shall be constructed of meal in accordance with 280.715(a)(2) or shall be listed Class 0 or Class 1 air ducts for those portions of the duct closer than 2 feet from the outer casing of the appliance. (v) Ducts applied to external appliances shall be resistant to deteriorating environmental effects, including but not limited to ultra violet rays, cold weather, or moisture and shall be resistant to insects and rodents.

(3) Sizing. The cross-sectional areas of the return air duct shall not be less than 2 square inches for each 1,000 Btu per hour input rating of the appliance. Dampers shall not be placed in a combination fresh air intake and return air duct so arranged that the required cross-sectional area will not be reduced at all possible positions of the damper.
(4) Permanent uncloseable openings. Living areas not served by return air ducts or closed off from the return opening of the furnace by doors, sliding partitions, or other means shall be provided with permanent uncloseable openings in the doors or separatiang partitions to allow circulated air to return to the furniace. Such openings may be grilled or louvered. The net free area of each opening shall not be less than 1 square inch for every 5 square feet of total living area closed off from the furniace by the door or partition serviced by that opening. Undercutting doors connecting the closed-off space may be used as a means of providing return air area. However, in the event that doors are undercut, they shall be undercut a minimum of 2 inches and no more than 2-1/2 inches, and no more than one half of the free air area so provided shall be counted as return air area.
(c) Joints and seams. Joints and seams of ducts shall be securely fastened and made substantially airtight. Slip joints shall have a lap of at least 1 inch and shall be individually fastened. Tape or caulking compound may be used for sealing mechanically secure joints. Where used, tape or caulking compound shall not be subject to deterioration under long exposures to temperatures up to 200° F and to conditions of high humidity, excessive moisture, or mildew.
(d) Supports. Ducts shall be securely supported.
(e) Registers or grilles. Fittings connecting the registers or grilles to the duct system shall be constructed of metal or material which complies with the requirements of Class 1 or 2 ducts under Underwriters' Laboratories, Inc. Standard for Air Ducts, UL181-1972. Air supply terminal devices (registers) when installed in kitchens, bedrooms and bathrooms shall be equipped with adjustable closeable dampers. Registers or grilles shall be constructed of metal or conform with the following:
(1) Be made of a material classified 94VE-0 or 94VE-1 when tested as described in Underwriters' Laboratories, Inc. Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances. UL94-1974.
(2) Floor register or grilles shall resist without structural failure a 200 lb. concentrated load on a 2-inch diameter disc applied to the most critical area of the exposed face of the register or grille. For this test the register or grille is to be at a temperature of not less than 165° F and is to be supported in accordance with the manufacturer's instructions.
Subpart I. Electrical Systems

280.801. Scope.
(a) Subpart I of this Standard and Part A of Article 550 of the National Electrical Code (NFPA No. 70-1975) cover the electrical conductors and equipment installed within or on mobile homes and the conductors that connect mobile homes to a supply of electricity.
(b) In addition to the requirements of this Standard and Article 550 of the National Electricla Code (NFPA No. 70-1975), the applicable portions of other Articles of the National Electrical Code shall be followed covering electrical installations in mobile homes. Whereever the requirements of this Standard differ from the National Electrical Code, this Standard shall apply.
(c) The provisions of this Standard apply to mobile homes intended for connection to a wiring system nominally rated 115/230 volts, 3-wire AC, with grounded neutral.
(d) All electrical materials, devices, appliances, fittings and other equipment shall be listed or labeled by a nationally recognized testing agency and shall be connected in an approved manner when in service.
(e) Aluminum conductors are not acceptable in branch circuit wiring in mobile homes except as specifically approved by the Department after examination of proposed systems for individual cases.
280.802. Definitions.
(a) The following definitions are applicable to Subpart I only.
(1) 'Accessible (i) (As Applied to Equipment)' means admitting close approach because not guarded by locked doors, elevation, or other effective means (see 'Readily Accessible'). (ii) (As Applied to Wiring Methods) means capable of being removed or exposed without damaging the mobile home structure or finish, or not permanently closed-in by the structure or finish of the mobile home (see 'Concealed' and 'Exposed').

(2)'Air Conditioning or Comfort Cooling Equipment' means all of that equipment intended or installed for the purpose of processing the treatment of air so as to control simultaneously its temperature, humidity, cleanliness, and distribution to meet the requirements of the conditioned space.
(3)(i) 'Appliance' means utilization equipment, generally other than industrial, normally built in standardized sizes or types, which is installed or connected as a unit to perform one or more functions, such as clothes washing, air conditioning, food mixing, deep frying, etc. (ii) 'Appliance, Fixed' means an appliance, 'Portable' means an appliance which is actually moved or can easily be moved from one place to another in normal use. For the purpose of this Standard, the following major appliances are considered portable if cord-connected: refrigerators, clothes washers, dishwashers without booster heaters, or other similar appliances. (iv) 'Appliance, Stationary' means an appliance which is not easily moved from one place to another in normal use.
(4) 'Attachment Plug (Plug Cap) (Cap)' means a device which, by insertion in a receptacle, establishes connection between the conductors of the attached flexible cord and the conductors connected permanently to the receptacle.

(5) 'Bonding' means the permanent joining of metallic parts to form an electrically conductive path which will assure electrical continuity and the capacity to conduct safely any current likely to be imposed.
(6) 'Branch Circuit' (i) means the circuit conductors between the final overcurrent device protecting the circuit and the outlet(s). A device not approved for branch circuit protection, such as a thermal cutout or motor overload protective device, is not considered as the overcurrent device protecting the circuit. (ii) 'Branch Circuit-Appliance' means a branch circuit supplying energy to one or more outlets to which appliances are to be connected; such circuits to have no permanently connected lighting fixtures not a part of an appliance. (iii) 'Branch Circuit-General Purpose' means a circuit that supplies a number of outlets for lighting and appliances. (iv) 'Branch Circuit-Individual' means a branch circuit that supplies only one utilization equipment.
(7) 'Cabinet' means an enclosure designed either for surface or flush mounting, and provided with a frame, mat, or trim in which swinging doors are hung.
(8) 'Circuit Breaker' means a device designed to open and close a circuit by nonautomatic means, and to open the circuit automatically on a predetermined overload of current without injury to itself when properly applied within its rating.
(9) 'Concealed' means rendered inaccessible by the structure or finish of the mobile home. Wires in concealed raceways are considered concealed, even though they become accessible by withdrawing them. (See 'Accessible (As Applied to Wiring Methods)')
(10) 'Connector, Pressure (Solderless)' means a device that establishes a connection between two or more conductors or between one or more conductors and a terminal by means of mechanical pressure and without the use of solder.
(11) 'Dead Front (As Applied to Switches, Circuit-Breakers, Switch-boards, and Distribution Panelboard)' means so designed, constructed, and installed that no current-carrying parts are normally exposed on the front.
(12) 'Demand Factor' means a ratio of the maximum demand of a system, or part of a system, to the total connected load of a system or the part of the system under consideration.
(13) 'Device' means a unit of an electrical system that is intended to carry but not utilize electrical energy.
(14) 'Disconnecting Means' means a device, or group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply.
(15) 'Distribution Panelboard' means a single panel or a group of panel units designed for assembly in the form of a single panel, including buses, and with or without switches or automatic overcurrent protective devices or both, for the control of light, heat, or power circuits of small individual as well as aggregate capacity; designed to be placed in a cabinet placed in or against a wall or partition and accessible only from the front.
(16) 'Enclosed' means surrounded by a case that will prevent a person from accidently contacting live parts.
(17) 'Equipment' means a general term, including material, fittings, devices, appliances, fixtures, apparatus, and the like used as a part of, or in connection with, an electrical installation.
(18) 'Exposed' (i) (As Applied to Live Parts) means capable of being inadvertently touched or approached nearer than a safe distance by a person. It is applied to parts not suitably guarded, isolated, or insulated.(See 'Accessible' and 'Concealed.') (ii) (As Applied to 'Wiring Method') means on or attached to the surface or behind panels designed to allow access. (See 'Accessible (As Applied to wiring Methods)')
(19) 'Externally Operable' means capable of being operated without exposing the operator to contact with live parts.
(20) 'Feeder Assembly' means the overhead or under-chassis feeder conductors, including the grounding conductor together with the necessary fittings and equipment, or a power supply cord approved for mobile home use, designed for the purpose of delivering energy from the source of electrical supply to the distribution panelboard within the mobile home.
(21) 'Fitting' means an accessory, such as a locknut, bushing, or other part of a wiring system, that is intended primarily to perform a mechanical rather than an electrical function.
(22) 'Ground' means a conducting connection, whether intentional or accidental, between an electrical circuit or equipment and earth, or to some conducting body that serves in place of the earth.
(23) 'Grounded' means connected to earth or to some conducting body that serves in place of the earth.
(24) 'Grounded Conductor' means a system or circuit conductor that is intentionally grounded.
(25) 'Grounding Conductor' means a conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes.
(26) 'Guarded' means covered, shielded, fenced, enclosed, or otherwise protected by means of suitable covers, casings, barriers, rails, screens, mats or platforms to remove the likelihood of approach or contact by persons or objects to a point of danger.
(27) 'Isolated' means not readily accessible to persons unless special means for access are used.
(28) 'Laundry Area' means an area containing or designed to contain either a laundry tray, clothes washer and/or clothes dryer.

(29) 'Lighting Outlet' means an outlet intended for the direct connection of a lampholder, a lighting fixture, or a pendant cord terminating in a lampholder.
(30) 'Mobile Home Accessory Building or Structure' means by awning, cabana, ramada, storage cabinet, carpot, fence, windbreak or porch established for the use of the occupant of the mobile home upon a mobile home lot.
(31) 'Mobile Home Service Equipment' means the equipment containing the disconnecting means overcurrent protective devices, and receptacles or other means for connecting a mobile home feeder assembly.
(32) 'Outlet' means a point on the wiring system at which current is taken to supply utilization equipment.
(33) 'Panelboard' means a single panel or group of panel units designed few assembly in the form of a single panel; including buses, automatic overcurrent protective devices, and with or without switches for the control of light, heat, or power circuits; designed to be placed in a cabinet or cutout box placed in or against a wall or partition and accessible only from the front.

(34) 'Raceway' means any channel for holding wires, cables, or busbars that is designed expressly for, and used solely for, this purpose. Raceways may be of metal or insulating material, and the term includes rigid metal conduit, rigid nonmetallic conduit, flexible metal conduit, electrical metallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, structural raceways, wireways, and busways.
(35) 'Raintight' means so constructed or protected that exposure to a beating rain will not result in the entrance of water.
(36) 'Readily Accessible' means capable of being reached quickly for operation, renewal, or inspection, without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, chains, etc. (See 'Accessible')
(37) 'Receptacle' means a contact device installed at an outlet for the connection of a single attachment plug. A single receptacle is a single contact device with no other contact device on the same yoke. A multiple receptacle is a single device containing two or more receptacles.
(38) 'Receptacle Outlet' means an outlet where one or more receptacles are installed.
(39) 'Utilization Equipment' means equipment which utilizes electric energy for mechanical, chemical, heating, lighting, or similar purposes.
(40) 'Voltage (of a Circuit)' means the greatest root-mean-square (effective) difference of potential between any two conductors of the circuit concerned. Some systems, such as 3-phase 4-wire, single-phase 3-wire, and 3-wire direct current may have various circuits of various voltages.
(41) 'Weatherproof' means so constructed or protected that exposure to the weather will not interfere with successful operation. Rainproof, raintight, or watertight equipment can fulfill the requirements for weatherproof where varying weather conditions other than wetness, such as snow, ice, dust, or temperature extremes, are not a factor.
280.803. Power Supply.
(a) The power supply to the mobile home shall be a feeder assembly consisting of not more than one listed 50 ampere mobile home power-supply cords, or a permanently installed circuit. A mobile home that is factory-equipped with gas or oil-fired central heating equipment and cooking appliances shall be permitted to be provided with a listed mobile home power-supply cord rated 40 amperes.
(b) If the mobile home has a power supply cord, it shall be permanently attached to the distribution panelboard or to a junction box permanently connected to the distribution panelboard, with the free end terminating in an attachment plug cap.
(c) Cords with adapters and pigtail ends, extension cords, and similar items shall not be attached to, or shipped with, a mobile home.
(d) A listed clamp or the equivalent shall be provided at the distribution panelboard knockout to afford strain relief for the cord to prevent strain from being transmitted to the terminals when the power-supply cord is handled in its intended manner.
(e) The cord shall be of an approved type with four conductors, one of which shall be identified by a continuous green color or a continuous green color with one or more yellow stripes for use as the grounding conductor.

(f) The attachment plug cap shall be a 3-pole, 4-wire grounding type, rated 50 amperes, 125/250 volts with a configuration as shown herein and intended for use with the 50-ampere, 125/250 receptacle configuration shown. It shall be molded of butyl rubber, neoprene, or other approved materials which have been found suitable for the purpose, and shall be molded to the flexible cord so that it adheres tightly to the cord at the point where the cord enters the attachment-plug cap. If a right-angle cap is used, the configuration shall be so oriented that the grounding member is farthest from the cord.
(g) The overall length of a power supply cord, measured from the end of the cord, including bared leads, to the face of the attachment-plug cap shall not be less than 21 feet and shall not exceed 36-1/2 feet. The length of cord from the face of the attachment-plug cap to the point where the cord enters the mobile home shall not be less and 20 feet.


50-ampere 125/250 volt receptacle and attachment-plug-cap-configurations, 3 pole, 4-wire grounding types used for mobile home supply cords and mobile home parks. Complete details of the 50-ampere cap and receptacle can be found in the American National Standard Dimensions of caps, Plugs and Receptacles, Grounding Type (ANSI C73.17-1972).
(h) The power-supply cord shall bear the following marking: 'For use with mobile homes--40 amperes' or 'For use with mobile homes--50 amperes.'
(i) The point of entrance of the feeder assembly to the mobile home shall be in the exterior wall, floor, or roof, in the rear third section (away from the coupler), of the mobile home.
(j) Where the cord passes through walls or floors, it shall be protected by means of conduit and bushings or equivalent. The cord may be installed within the mobile home walls, provided a continuous raceway is installed from the branch-circuit panelboard to the underside of the mobile home floor. The raceway may be rigid conduit, electrical metallic tubing or polyethylene (PE), poly-vinylchloride (PVC) or acrylonitrile-butadiene-styrene (ABS) plastic tubing having a minimum wall thickness of nominal 1/8 inch.
(k) Permanent provisions shall be made for the protection of the attachment-plug cap of the power supply cord and any connector cord assembly or receptacle against corrosion and mechanical damage if such devices are in an exterior location while the mobile home is in transit.
(l) Where the calculated load exceeds 50 amperes or where a permanent feeder is used, the supply shall be by means of:
(1) One mast weatherhead installation installed in accordance with Article 230 of the National Electrical Code NFPA No. 70-1975 containing four continuous insulated, color-coded feeder conductors, one of which shall be an equipment grounding conductor; or
(2) An approved raceway from the disconnecting means in the mobile home to the underside of the mobile home with provisions for the attachment of a suitable junction box or fitting to the raceway on the underside of the mobile home. The manufacturer shall provide in his written installation instructions, the proper feeder conductor sizes for the raceway and the size of the junction box to be used.
280.804. Disconnecting Means and Branch-Circuit Protective Equipment.
(a) The branch-circuit equipment shall be permitted to be combined with the disconnecting means as a single assembly. Such a combination shall be permitted to be designated as a distribution panelboard. If a fused distribution panelboard is used, the maximum fuse size of the mains shall be plainly marked with lettering at least 1/4-inch high and visible when fuses are changed. See Section 110-22 of the National Electrical Code (NFPA No. 70-1975) concerning identification of each disconnecting means and each service, feeder, or branch circuit at the point where it originated and the type marking needed.

(b) Plug fuses and fuseholders shall be tamper-resistant. Type 'S,' enclosed in dead-front fuse panelboards. Electrical distribution panels containing circuit breakers shall also be dead-front type.
(c) Disconnecting means. A single disconnecting means shall be provided in each mobile home consisting of a circuit breaker, or a switch and fuses and their accessories installed in a readily accessible location near the point of entrance of the supply cord or conductors into the mobile home. The main circuit breakers or fuses shall be plainly marked 'Main.' This equipment shall contain a solderless type of grounding connector or bar for the purposes of grounding with sufficient terminals for all grounding conductors. The neutral bar termination of the grounded circuit conductors shall be insulated.
(d) The disconnecting equipment shall have a rating suitable for the connected load. The distribution equipment, either circuit breaker or fused type, shall be located a minimum of 24 inches from the bottom of such equipment to the floor level of the mobile home. There shall be a label attached to the panelboard stating: This Panelboard shall be connected by a Feeder Assembly having Overcurrent Protection rated at not more than _______ Amperes. The correct ampere rating shall be marked in a blank space.

(e) A distribution panelboard employing a main circuit breaker shall be rated 50 amperes and employ a 2-pole circuit breaker rated 40 amperes for a 40-ampere supply cord, or 50 amperes for a 50- ampere supply cord. A distribution panelboard employing a disconnect switch and fuses shall be rated 60 amperes and shall employ a single 2-pole, 60-ampere fuseholder with 40- or 50-ampere main fuses for 40- or 50-ampere supply cords, respectively. The outside of the distribution panelboard shall be plainly marked with the fuse size.
(f) The distribution panelboard shall not be located in a bathroom, or in any other inaccessible location, but shall be permitted just inside a closet entry if the location is such that a clear space of 6 inches to easily ignitable materials is maintained in front of the distribution panelboard, and the distribution panelboard door can be extended to its full open position (at least 90 degrees). A clear working space at least 30 inches wide and 30 inches in front of the distribution panelboard shll be provided. This space shall extend from floor to the top of the distribution panelboard.
(g) Branch-circuit distribution equipment shall be installed in each mobile home and shall include overcurrent protection for each branch circuit consisting of either circuit breakers or fuses.

(1) The branch circuit overcurrent devices shall be rated: (i) not more than the circuit conductors; and (ii) not more than 150 percent of the rating of a single appliance rated 10 amperes or more which is supplied by an individual branch circuit; but (iii) not more than the fuse size marked on the air conditioner or other motor-operated appliance.
(h) A 15-ampere multiple receptacle shall be acceptable when connected to a 20- ampere laundry circuit.
(i) When circuit breakers are provided for branch-circuit protection, 230-volt circuits shall be protected by 2-pole common or companion trip, or handle-tied paired circuit breakers.
(j) A metal nameplate on the outside adjacent to the feeder assembly entrance shall read: This Connection for 120/240 Volt, 3-Pole, 4-Wire, 60 Hertz _______ Ampere Supply. The correct ampere rating shall be marked in the blank space.
280.805. Branch Circuits Required.
(a) The number of branch circuits required shall be determined in accordance with the following:

(1) Lighting. Based on 3 watts per square foot times outside dimensions of the mobile home (coupler excluded) divided by 115 volts times amperage to determine number of 15- or 20-ampere lighting area circuits, e.g.,
(2) Portable appliances. For the small appliance load in kitchen, pantry, family room, dining room and breakfast rooms of mobile homes, two or more 20- ampere appliance branch circuits, in addition to the branch circuit specified in 280.805(a)(1), shall be provided for all receptacle outlets in these rooms, and such circuits shall have no other outlets. Receptacle outlets supplied by at least two appliance receptacle branch circuits shall be installed in the kitchen.
(3) General appliances (Including furnace, water heater, range, and central or room air conditioner, etc.). There shall be one or more circuits of adequate rating in accordance with the following: (i) Ampere rating of fixed appliances not over 50 percent of circuit rating if lighting outlets (receptacles, other than kitchen, dining area, and laundry, considered as lighting outlets) are on the same circuits; (ii) For fixed appliances on a circuit without lighting outlets, the sum of rated amperes shall not exceed the branch-circuit rating for air conditioning or other motor loads; (iii) The rating of a single portable appliance on a circuit having no other outlets shall not exceed 80 percent of the circuit rating: (iv) the rating of range branch circuit shall be based on the range demand as specified for ranges in 280.811. Item B(5) of Method 1. For central air conditioning, see Article 440 of the National Electrical Code (NFPA No. 70-1975). Where laundry facilities are provided in a mobile home, a 20-amperes branch circuit shall be provided within 6 feet of the intended location of the appliance. (See 280.804(j). (continued)