Title 24—Housing and Urban Development--Volume 1
PART 3280—MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS
§ 3280.505   Air infiltration.
(a) Envelope air infiltration. The opaque envelope shall be designed and constructed to limit air infiltration to the living area of the home. Any design, material, method or combination thereof which accomplishes this goal may be used. The goal of the infiltration control criteria is to reduce heat loss/heat gain due to infiltration as much as possible without impinging on health and comfort and within the limits of reasonable economics.
(1) Envelope penetrations. Plumbing, mechanical and electrical penetrations of the pressure envelope not exempted by this part, and installations of window and door frames shall be constructed or treated to limit air infiltration. Penetrations of the pressure envelope made by electrical equipment, other than distribution panel boards and cable and conduit penetrations, are exempt from this requirement. Cable penetrations through outlet boxes are considered exempt.
(2) Joints between major envelope elements. Joints not designed to limit air infiltration between wall-to-wall, wall-to-ceiling and wall-to-floor connections shall be caulked or otherwise sealed. When walls are constructed to form a pressure envelope on the outside of the wall cavity, they are deemed to meet this requirement.
§ 3280.506   Heat loss/heat gain.
(a) The manufactured home heat loss/heat gain shall be determined by methods outlined in §§ 3280.508 and 3280.509. The Uo (Coefficient of heat transmission) value zone for which the manufactured home is acceptable and the lowest outdoor temperature to which the installed heating equipment will maintain a temperature of 70 F shall be certified as specified in § 3280.510. The Uo value zone shall be determined from the map in figure 1 to this paragraph (a).
Figure 1 to Paragraph (a)
(b) The overall coefficient of heat transmission (Uo) of the manufactured home for the respective zones and an indoor design temperature of 70 F, including internal and external ducts, and excluding infiltration, ventilation, and condensation control, shall not exceed the Btu/(hr.) (sq. ft.) (F) of the manufactured home envelope are as tabulated in the table to this paragraph (b):
Table 1 to Paragraph (b)
(c) To assure uniform heat transmission in manufactured homes, cavities in exterior walls, floors, and ceilings must be provided with thermal insulation. For insulation purposes, the fire separation wall between each single family attached manufactured home shall be considered an exterior wall (see subpart K of this part).
(d) Manufactured homes designed for Uo Value Zone 3 shall be factory equipped with storm windows or insulating glass.
§ 3280.507   Comfort heat gain.
Information necessary to calculate the home cooling load shall be provided as specified in this part.
(a) Transmission heat gains. Homes complying with this section shall meet the minimum heat loss transmission coefficients specified in § 3280.506(a).
§ 3280.508   Heat loss, heat gain and cooling load calculations.
(a) Information, values and data necessary for heat loss and heat gain determinations must be taken from the 1997 ASHRAE Handbook of Fundamentals, Inch-Pound Edition, chapters 22 through 27. The following portions of those chapters are not applicable:
(b) The calculation of the manufactured home's transmission heat loss coefficient (Uo) must be in accordance with the fundamental principles of the 1997 ASHRAE Handbook of Fundamentals, Inch-Pound Edition, and, at a minimum, must address all the heat loss or heat gain considerations in a manner consistent with the calculation procedures provided in the document, Overall U-values and Heating/Cooling Loads—Manufactured Homes—February 1992-PNL 8006, HUD User No. 0005945.
(c) Areas where the insulation does not fully cover a surface or is compressed shall be accounted for in the U-calculation (see § 3280.506). The effect of framing on the U-value must be included in the Uo calculation. Other low-R-value heat-flow paths (“thermal shorts”) shall be explicitly accounted for in the calculation of the transmission heat loss coefficient if in the aggregate all types of low-R-value paths amount to more than 1% of the total exterior surface area. Areas are considered low-R-value heat-flow paths if:
(1) They separate conditioned and unconditioned space; and
(2) They are not insulated to a level that is at least one-half the nominal insulation level of the surrounding building component.
(d) High efficiency heating and cooling equipment credit. The calculated transmission heat loss coefficient (Uo) used for meeting the requirement in § 3280.506(a) may be adjusted for heating and cooling equipment above that required by the National Appliance Energy Conservation Act of 1987 (NAECA) by applying the following formula:
The cooling multiplier for the Uo Zone is from the following table:
(e) U values for any glazing (e.g., windows, skylights, and the glazed portions of any door) must be based on tests using AAMA 1503.1-1988, Voluntary Test Method for Thermal Transmittance and Condensation Resistance of Windows, Doors, and Glazed Wall Sections, or the National Fenestration Rating Council 100, 1997 Edition, Procedure for Determining Fenestration Product U-factors. In the absence of tests, manufacturers are to use the residential window U values contained in Chapter 29, Table 5 of the 1997 ASHRAE Handbook of Fundamentals, Inch-Pound Edition. In the event that the classification of the window type is indeterminate, the manufacturer must use the classification that gives the higher U value. Where a composite of materials from two different product types is used, the product is to be assigned the higher U value. For the purpose of calculating U o values, storm windows are treated as an additional pane.
(f) Annual energy used based compliance. As an alternative, homes may demonstrate compliance with the annual energy used implicit in the coefficient of heat transmission (Uo) requirement. The annual energy use determination must be based on generally accepted engineering practices. The general requirement is to demonstrate that the home seeking compliance approval has a projected annual energy use, including both heating and cooling, less than or equal to a similar “base case” home that meets the standard. The energy use for both homes must be calculated based on the same assumptions; including assuming the same dimensions for all boundaries between conditioned and unconditioned spaces, site characteristics, usage patterns and climate.
§ 3280.509   Criteria in absence of specific data.
In the absence of specific data, for purposes of heat-loss/gain calculation, the following criteria shall be used:
(a) Infiltration heat loss. In the absence of measured infiltration heat loss data, the following formula shall be used to calculate heat loss due to infiltration and intermittently operated fans exhausting to the outdoors. The perimeter calculation shall be based on the dimensions of the pressure envelope.
(b) Framing areas.
(c) Insulation compression. Insulation compressed to less than nominal thickness and loose-fill insulation in sloping cavities must have its nominal R-values reduced in compressed areas in accordance with the following table:
Table to Paragraph (c)—Effect of Insulation Compression and Restriction on R -Values
Note: To use this table, first compute the restricted insulation thickness as a fraction of the uncompressed (full) insulation thickness. Then look up the R -value remaining from the appropriate column (Non-uniform Restriction, Batt Non-uniform Restriction, Blown or Uniform Compression, Batt). Example: Assume a section of loose-fill ceiling insulation went from R -25 insulation at a height of 10 inches to a minimum height of 2 inches at the edge of the ceiling. The ratio of minimum to full thickness is 0.20 (2 divided by 10). Look up 0.20 (20 percent), read across to column 3 (Non-uniform Restriction, Blown), and read 50 percent. Therefore, the R -value of the loose-fill insulation over the restricted area would be R -12.5 (50 percent of 25).
(a) Non-uniform restriction is that which occurs between non-parallel planes, such as in the ceiling near the eaves.
(b) Uniform compression is compression between parallel planes, such as that which occurs in a wall.
(d) Air supply ducts within floor cavity. Air supply ducts located within a floor cavity shall be assumed to be heating or cooling the floor cavity to living space temperatures unless the duct is structurally isolated by the framing system or thermally insulated from the rest of the floor cavity with a thermal insulation at least equal to R-4.
(e) Air supply ducts within ceiling cavity. Where supply ducts are located in ceiling cavities, the influence of the duct on cavity temperatures shall be considered in calculating envelope heat loss or heat gain.
(f) The supply duct loss (and/or heat gain where applicable—See § 3280.511) shall be calculated using the actual duct surface area and the actual thickness of insulation between the duct and outside of the manufactured home. If there is an air space of at least 1/2 inch between the duct and the insulation, heat loss/gain need not be calculated if the cavity in which the duct is located is assumed to be at living space temperature. The average temperature inside the supply duct, including ducts installed outside the manufactured home, shall be assumed to be 130 F for purposes of calculation of heat loss and 60 F for heat gain.
(g) Return air cavities. Cavities used as return air plenums shall be considered to be at living space temperature.
§ 3280.510   Heat loss certificate.
The manufactured home manufacturer shall permanently affix the following “Certificate” to an interior surface of the home that is readily visible to the homeowner. The “Certificate” shall specify the following:
(a) Heating zone certification. The design zone at which the manufactured home heat loss complies with § 3280.506(a).
(b) Outdoor certification temperature. The lowest outdoor temperature at which the installed heating equipment will maintain a 70 °F temperature inside the home without storm sash or insulating glass for Zones 1 and 2, and with storm sash or insulating glass for Zone 3 and complying with § 3280.508 and § 3280.509.
(c) Operating economy certification temperature. The temperature to be specified for operating economy and energy conservation shall be 20 °F or 30% of the design temperature difference, whichever is greater, added to the temperature specified as the heating system capacity certification temperature without storm windows or insulating glass in Zones 1 and 2 and with storm windows or insulating glass in Zone 3. Design temperature difference is 70° minus the heating system capacity certification temperature in degrees Fahrenheit.
This manufactured home has been thermally insulated to conform with the requirements of the Federal Manufactured Home Construction and Safety Standards for all locations within Uo Value Zone ____.
The above heating equipment has the capacity to maintain an average 70F temperature in this home at outdoor temperatures of [see paragraph (b) of this section] F. To maximize furnace operating economy and to conserve energy, it is recommended that this home be installed where the outdoor winter design temperature (97 1/2%) is not higher than [see paragraph (c) of this section] F degrees Fahrenheit.
The above information has been calculated assuming a maximum wind velocity of 15 MPH at standard atmospheric pressure.
(d) The following additional statement must be provided on the heating certificate and data plate required by § 3280.5 when the home is built with a vapor retarder of not greater than one perm (dry cup method) on the exterior side of the insulation: “This home is designed and constructed to be sited only in humid or fringe climate regions as shown on the Humid and Fringe Climate Map.” A reproduction of the Humid and Fringe Climate Map in § 3280.504 is to be provided on the heating certificate and data plate. The map must be not less than 3 1/2 inch × 2 1/4 inch in size and may be combined with the U o Value Zone Map for Manufactured Housing in § 3280.506.
§ 3280.511   Comfort cooling certificate and information.
(a) The manufactured home manufacturer shall permanently affix a “Comfort Cooling Certificate” to an interior surface of the home that is readily visible to the home owner. This certificate may be combined with the heating certificate required in § 3280.510. The manufacturer shall comply with one of the following three alternatives in providing the certificate and additional information concerning the cooling of the manufactured home:
(1) Alternative I. If a central air conditioning system is provided by the home manufacturer, the heat gain calculation necessary to properly size the air conditioning equipment shall be in accordance with procedures outlined in chapter 22 of the 1989 ASHRAE Handbook of Fundamentals, with an assumed location and orientation. The following shall be supplied in the Comfort Cooling Certificate:
Certified Capacity ______ BTU/Hr. in accordance with the appropriate Air Conditioning and Refrigeration Institute Standards
The central air conditioning system provided with this home has been sized, assuming an orientation of the front (hitch) end of the home facing ______ and is designed on the basis of a 75 °F indoor temperature and an outdoor temperature of __ °F dry bulb and __ °F wet bulb.
Certified Capacity ______ BTU/Hr. in accordance with the appropriate Air Conditioning and Refrigeration Institute Standards.
The central air conditioning system provided with this home has been sized assuming an orientation of the front (hitch end) of the home facing ______. On this basis, the system is designed to maintain an indoor temperature of 75 °F when outdoor temperatures are __ °F dry bulb and __ °F wet bulb.
The temperature to which this home can be cooled will change depending upon the amount of exposure of the windows to the sun's radiant heat. Therefore, the home's heat gains will vary dependent upon its orientation to the sun and any permanent shading provided. Information concerning the calculation of cooling loads at various locations, window exposures and shadings are provided in chapter 22 of the 1989 edition of the ASHRAE Handbook of Fundamentals.
(2) Alternative 2. For each home suitable for a central air cooling system, the manufacturer shall provide the following statement: “This air distribution system of this home is suitable for the installation of a central air conditioning system.”
This air distribution system of this home is suitable for the installation of central air conditioning.
The supply air distribution system installed in this home is sized for Manufactured Home Central Air Conditioning System of up to ______ B.T.U./Hr. rated capacity which are certified in accordance with the appropriate Air Conditioning and Refrigeration Institute Standards. When the air circulators of such air conditioners are rated at 0.3 inch water column static pressure or greater for the cooling air delivered to the manufactured home supply air duct system.
Information necessary to calculate cooling loads at various locations and orientations is provided in the special comfort cooling information provided with this manufactured home.
(3) Alternative 3. If the manufactured home is not equipped with an air supply duct system, or if the manufacturer elects not to designate the home as being suitable for the installation of a central air conditioning system, the manufacturer shall provide the following statement: “This air distribution system of this home has not been designed in anticipation of its use with a central air conditioning system.”
The air distribution system of this home has not been designed in anticipation of its use with a central air conditioning system.
(b) For each home designated as suitable for central air conditioning the manufacturer shall provide the maximum central manufactured home air conditioning capacity certified in accordance with the ARI Standard 210/240-89 Unitary Air-Conditioning and Air-Source Heat Pump Equipment and in accordance with § 3280.715(a)(3). If the capacity information provided is based on entrances to the air supply duct at other than the furnace plenum, the manufacturer shall indicate the correct supply air entrance and return air exit locations.
(c) Comfort cooling information. For each manufactured home designated, either “suitable for” or “provided with” a central air conditioning system, the manufacturer shall provide comfort cooling information specific to the manufactured home necessary to complete the cooling load calculations. The comfort cooling information shall include a statement to read as follows:
To determine the required capacity of equipment to cool a home efficiently and economically, a cooling load (heat gain) calculation is required. The cooling load is dependent on the orientation, location and the structure of the home. Central air conditioners operate most efficiently and provide the greatest comfort when their capacity closely approximates the calculated cooling load. Each home's air conditioner should be sized in accordance with chapter 22 of the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Handbook of Fundamentals, 1989 Edition, once the location and orientation are known.
§ 3280.601   Scope.
Subpart G of this standard covers the plumbing materials, fixtures, and equipment installed within or on manufactured homes. It is the intent of this subpart to assure water supply, drain, waste and vent systems which permit satisfactory functioning and provide for health and safety under all conditions of normal use.
§ 3280.602   Definitions.
The following definitions are applicable to subpart G only:
Accessible, when applied to a fixture, connection, appliance or equipment, means having access thereto, but which may require removal of an access panel or opening of a door.
Air gap (water distribution system) means the unobstructed vertical distance through the free atmosphere between the lowest opening from any pipe or faucet supplying water to a tank, plumbing fixture, water supplied appliances, or other device and the flood level rim of the receptacle.
Backflow means the flow of water or other liquids, mixtures, or substances into the distributing pipes of a potable supply of water from any source or sources other than its intended sources.
Backflow connection means any arrangement whereby backflow can occur.
Backflow preventer means a device or means to prevent backflow.
Branch means any part of the piping system other than a riser, main or stack.
Common vent means a vent connecting at the junction of fixture drains and serving as a vent for more than one fixture.
Continuous vent means a vertical vent that is a continuation of the drain to which it connects.
Continuous waste means a drain from two or more fixtures connected to a single trap.
Critical level means a point established by the testing laboratory (usually stamped on the device by the manufacturer) which determines the minimum elevation above the flood level rim of the fixture or receptacle served on which the device may be installed. When a backflow prevention device does not bear a critical level marking, the bottom of the vacuum breaker, combination valve, or of any such approved or listed device shall constitute the critical level.
Cross connection means any physical connection or arrangement between two otherwise separate systems or sources, one of which contains potable water and the other either water, steam, gas or chemical of unknown or questionable safety whereby there may be a flow from one system or source to the other, the direction of flow depending on the pressure differential between the two systems.
Developed length means that length of pipe measured along the center line of the pipe and fittings.
Diameter, unless otherwise specifically stated, means the nominal (inside) diameter designated commercially.
Drain means a pipe that carries waste, water, or water-borne waste in a drainage system.
Drain connector means the removable extension, consisting of all pipes, fittings and appurtenances, from the drain outlet to the drain inlet serving the manufactured home.
Drain outlet means the lowest end of the main or secondary drain to which a sewer connection is made.
Drainage system means all piping within or attached to the structure that conveys sewage or other liquid waste to the drain outlet, not including the drain connector.
Fixture drain means the drain from the trap of a fixture to the junction of that drain with any other drain pipe.
Fixture supply means the water supply pipe connecting a fixture to a branch water supply pipe or directly to a main water supply pipe.
Flood-level means the level in the receptacle over which water would overflow to the outside of the receptacle.
Flooded means the condition which results when the liquid in a container or receptacle rises to the flood-level.
Flush tank means that portion of a water closet that is designed to contain sufficient water to adequately flush the fixture.
Flush valve means a device located at the bottom of a flush tank for flushing a water closet.
Flushometer tank: means a device integrated within an air accumulator vessel which is designed to discharge a predetermined quantity of water to fixtures for flushing purposes.
Flushometer valve means a device which discharges a predetermined quantity of water to a fixture for flushing purposes and is closed by direct water pressure.
Grade means the fall (slope) of a pipe in reference to a horizontal plane expressed in inches per foot length.
Horizontal branch means any pipe extending laterally, which receives the discharge from one or more fixture drains and connects to the main drain.
Horizontal pipe means any pipe or fitting which makes an angle of not more than 45 degrees with the horizontal.
Indirect waste receptor means a receptor that receives a discharge waste pipe that is not directly connected to a receptor but maintains a suitable air gap between the end of the pipe and the top of the drain.
Individual vent means a pipe installed to vent a fixture drain.
Inlet coupling means the terminal end of the water system to which the water service connection is attached. It may be a swivel fitting or threaded pipe end.
Main means the principal artery of the system to which branches may be connected.
Main drain means the lowest pipe of a drainage system which receives sewage from all the fixtures within a manufactured home and conducts these wastes to the drain outlet.
Main vent means the principal artery of the venting system to which vent branches may be connected.
Mechanical trap vent device means a device that automatically opens to admit air to a fixture drain above the connection of the trap arm so as to prevent siphonage, and closes tightly when the pressure within the drainage system is equal to or greater than atmospheric pressure, so as to prevent the escape of gases from the drainage system into the manufactured home.
Offset means a combination of pipe and/or fittings that brings one section of the pipe out of line but into a line parallel with the other section.
Pitch. See Grade.
Plumbing appliance: means any one of a special class of plumbing fixture which is intended to perform a special plumbing function. Its operation and/or control may be dependent upon one or more energized components, such as motors, control, heating elements, or pressure or temperature-sensing elements. Such fixture may operate automatically through one or more of the following actions: A time cycle, a temperature range, a pressure range, a measured volume or weight, or the fixture may be manually adjusted or controlled by the user or operator.
Plumbing appurtenance: means a manufactured device, or a prefabricated assembly, or an on-the-job assembly of component parts, and which is an adjunct to the basic piping system and plumbing system and plumbing fixtures. An appurtenance demands no additional water supply, nor does it add any discharge load to a fixture or the drainage system.
Plumbing fixtures means receptacles, devices, or appliances which are supplied with water or which receive liquid or liquid-borne wastes for discharge into the drainage system.
Plumbing system means the water supply and distribution pipes; plumbing fixtures, faucets and traps; soil, waste and vent pipes; and water-treating or water-using equipment.
Primary vent. See main vent.
Relief vent means an auxiliary vent which permits additional circulation of air in or between drainage and vent systems.
Secondary vent means any vent other than the main vent or those serving each toilet.
Sewage means any liquid waste containing animal or vegetable matter in suspension or solution, and may include liquids containing chemicals in solution.
Siphonage means the loss of water seal from fixture traps resulting from partial vacuum in the drainage system which may be of either of the following two types, or a combination of the two:
(a) Self-siphonage resulting from vacuum in a fixture drain generated solely by the discharge of the fixture served by that drain, or,
(b) Induced siphonage resulting from vacuum in the drainage system generated by the discharge of one or more fixtures other than the one under observation.
Trap means a fitting or device designed and constructed to provide a liquid seal that will prevent the back passage of air without materially affecting the flow of liquid waste through it.
Trap arm means the portion of a fixture drain between a trap and its vent.
Trap seal means the vertical depth of liquid that a trap will retain.
Vacuum breaker. See backflow preventer.
Vent cap means the device or fitting which protects the vent pipe from foreign substance with an opening to the atmosphere equal to the area of the vent it serves.
Vent system means that part of a piping installation which provides circulation of air within a drainage system.
Vertical pipe means any pipe or fitting which makes an angle of not more than 45 degrees with the vertical.
Water closet drain means that part of the drainage piping which receives the discharge from each individual water closet.
Water connection means the fitting or point of connection for the manufactured home water distribution system designed for connection to a water supply.
Water connector means the removable extension connecting the manufactured home water distribution system to the water supply.
Water distribution system means potable water piping within or permanently attached to the manufactured home.
Wet vent means a vent which also serves as a drain for one or more fixtures.
Wet vented drainage system means the specially designed system of drain piping that also vents one or more plumbing fixtures by means of a common waste and vent pipe.
Whirlpool bathtub means a plumbing appliance consisting of a bathtub fixture which is equipped and fitted with a circulation piping system, pump, and other appurtenances and is so designed to accept, circulate, and discharge bathtub water upon each use.
§ 3280.603   General requirements.
(a) Minimum requirements. Any plumbing system installed in a manufactured home shall conform, at least, with the provisions of this subpart.
(1) General. The plumbing system shall be of durable material, free from defective workmanship, and so designed and constructed as to give satisfactory service for a reasonable life expectancy.
(2) Conservation. Each water closet must not use more than 1.6 gallons of water per flush.
(3) Connection to drainage system. All plumbing, fixtures, drains, appurtenances, and appliances designed or used to receive or discharge liquid waste or sewage shall be connected to the manufactured home drainage system in a manner provided by this standard.
(4) Workmanship. All design, construction, and workmanship shall be in conformance with accepted engineering practices and shall be of such character as to secure the results sought to be obtained by this standard.
(5) Components. Plumbing materials, devices, fixtures, fittings, equipment, appliances, appurtenance, and accessories intended for use in or attached to a manufactured home shall conform to one of the applicable standards referenced in § 3280.604. Where an applicable standard is not referenced, or an alternative recognized standard is utilized, the plumbing component shall be listed by a nationally recognized testing laboratory, inspection agency or other qualified organization as suitable for the intended use.
(6) Prohibited fittings and practices. (i) Drainage or vent piping shall not be drilled and tapped for the purpose of making connections.
(ii) Except as specifically provided elsewhere in this standard, vent pipes shall not be used as waste or drain pipes.
(iii) Fittings, connections, devices, or methods of installation that obstruct or retard the flow of sewage, or air in the drainage or venting systems in an amount greater than the normal frictional resistance to flow shall not be used unless their use is acceptable in this standard or their use is accepted as having a desirable and acceptable function of ultimate benefit to the proper and continued functioning of the plumbing system.
(iv) Cracks, holes, or other imperfections in materials shall not be concealed by welding, brazing, or soldering or by paint, wax, tar, or other leak-sealing or repairing agents.
(v) Piping, fixtures or equipment shall be located so as not to interfere with the normal use or with the normal operation and use of windows, doors or other required facilities.
(vi) Galvanized pipe shall not be bent or welded.
(7) Alignment of fittings. All valves, pipes, and fittings shall be installed in correct relationship to the direction of flow.
(b) Protective requirements. (1) Cutting structural members. Structural members shall not be unnecessarily or carelessly weakened by cutting or notching.
(2) Exposed piping. All piping, pipe threads, hangers, and support exposed to the weather, water, mud, and road hazard, and subject to damage therefrom, shall be painted, coated, wrapped, or otherwise protected from deterioration.
(3) Road damage. Pipes, supports, drains, outlets, or drain hoses shall not extend or protrude in a manner where they could be unduly subjected to damage during transit.
(4) Freezing. All piping and fixtures subject to freezing temperatures shall be insulated or protected to prevent freezing, under normal occupancy. The manufacturer shall provide:
(i) Written installation instructions for the method(s) required for compliance to this section;
(ii) A statement in the installation instructions required by § 3280.306(b), stating that if the heat tape or pipe heating cable is used, it must be listed for use with manufactured homes.
(iii) A receptacle outlet complying with § 3280.806(d)(10).
(5) All piping, except the fixture trap, shall be designed to allow drainage.
(6) Rodent resistance. All exterior openings around piping and equipment shall be sealed to resist the entrance of rodents.
(7) Piping and electrical wiring shall not pass through the same holes in walls, floors or roofs. Plastic piping shall not be exposed to heat in excess of manufacturers recommendation or radiation from heat producing appliances.
§ 3280.604   Materials.
(a) Minimum standards. Materials, devices, fixtures, fittings, equipment, appliances, appurtenances and accessories shall conform to one of the standards in the following table and be free from defects. Where an appropriate standard is not indicated in the table or a standard not indicated in the table is preferred, the item may be used if it is listed. A listing is also required when so specified in other sections of this subpart.
(b) Where more than one standard is referenced for a particular material or component, compliance with only one of those standards is acceptable. Exceptions:
(1) When one of the reference standards requires evaluation of chemical, toxicity or odor properties which are not included in the other standard, then conformance to the applicable requirements of each standard shall be demonstrated;
(2) When a plastic material or component is not covered by the Standards in the following table, it must be certified as non-toxic in accordance with ANSI/NSF 61-2001, Drinking water system components—Health effects.
Standard Specification for Crosslinked Polyethylene (PEX) Tubing—ASTM F876-10 (incorporated by reference, see § 3280.4).
Standard Specification for Crosslinked Polyethylene (PEX) Plastic Hot- and Cold-Water Distribution Systems—ASTM F877-07 (incorporated by reference, see § 3280.4).
Standard Specification for Rubber Gaskets for Cast Iron Soil Pipe and Fittings, ASTM C564-97 (incorporated by reference, see § 3280.4).
Relief Valves for Hot Water Supply Systems, ANSI Z21.22-1999 (incorporated by reference, see § 3280.4).
Standard for Safety Glazing Materials used in Buildings—Safety Performance Specifications and Methods of Test, ANSI Z97.1-2004 (incorporated by reference, see § 3280.4).
Performance Requirements for Automatic Compensating Values for Individual Shower and Tub/Shower Combinations, approved January 2005 ASSE 1016-2005 (incorporated by reference, see § 3280.4).
Performance Requirements for Water Temperature Limiting Devices, approved February 2004, ASSE 1070-2004 (incorporated by reference, see § 3280.4).
§ 3280.605   Joints and connections.
(a) Tightness. Joints and connections in the plumbing system shall be gastight and watertight for the pressures required under testing procedures.
(b) Assembling of pipe. All joints and connections shall be correctly assembled for tightness. Pipe threads shall be fully engaged with the threads of the fitting. Plastic pipe and copper tubing shall be inserted to the full depth of the solder cup or welding sockets of each fitting. Pipe threads and slip joints shall not be wrapped with string, paper, putty, or similar fillers.
(c) Threaded joints. Threads for screw pipe and fittings shall conform to the approved or listed standard. Pipe ends shall be reamed out to size of bore. All burrs, chips, cutting oil and foreign matter shall be removed. Pipe joint cement or thread lubricant shall be of approved type and applied to male threads only.
(d) Solder joints. Solder joints for tubing shall be made with approved or listed solder type fittings. Surfaces to be soldered shall be cleaned bright. The joints shall be properly fluxed with noncorrosive paste type flux and, for manufactured homes to be connected to a public water system, made with solder having not more than 0.2 percent lead.
(e) Plastic pipe, fittings and joints. Plastic pipe and fittings shall be joined by installation methods recommended by the manufacturer or in accordance with the provisions of a recognized, approved, or listed standard.
(f) Union joints. Metal unions in water piping shall have metal-to-metal ground seats.
(g) Flared joints. Flared joints for soft-copper water tubing shall be made with approved or listed fittings. The tubing shall be expanded with a proper flaring tool.
(h) Cast iron soil pipe joints. Approved or listed cast iron pipe may be joined as follows:
(1) Approved or listed hub-less pipe and fittings must be permitted to be joined with listed couplings or adapters, per the manufacturer's recommendations.
(2) Hub and plain-end soil pipe may be joined by compression fittings per the manufacturer's recommendation.
§ 3280.606   Traps and cleanouts.
(a) Traps —(1) Traps required. Each plumbing fixture, except listed toilets, shall be separately trapped by approved water seal “P” traps. All traps shall be effectively vented.
(2) Combination Fixtures. For the purposes of drainage and ventilation requirements, a two- or three-compartment sink, up to three single sinks, or up to three lavatories may be connected to one “P” trap and considered as a single fixture, so long as the sinks and lavatories are in the same room, have waste outlets not more than 30 inches apart, and have flood level rims at the same level. The “P” trap must be installed at the center fixture when three such fixtures are installed.
(3) Prohibited traps. A trap which depends for its seal upon concealed interior partitions shall not be used. Full “S” traps, bell traps, drum traps, crown-vented traps, and running traps are prohibited. Fixtures shall not be double-trapped.
(4) Material and design. Each trap shall be self-cleaning with a smooth and uniform interior waterway. Traps shall be manufactured of cast iron, cast brass, or drawn brass tubing of not less than No. 20 Brown and Sharpe gage, or approved or listed plastic, or other approved or listed material. Union joints for a trap shall be beaded to provide a shoulder for the union nut. Each trap shall have the manufacturer's name stamped or cast in the body of the trap, and each tubing trap shall show the gage of the tubing.
(5) Trap seal. Each “P” trap shall have a water seal of not less than 2 inches and not more than 4 inches and shall be set true to its seal.
(6) Size. Traps shall be not less than 1 1/4 inches in diameter. A trap shall not be larger than the waste pipe to which it is connected.
(7) Location. Each trap shall be located as close to its vent and to its fixture outlet as structural conditions will permit.
(8) Length of tailpiece. The vertical distance from a trap to the fixture outlet shall not exceed 24 inches.
(9) Installation. (i) Grade of trap arm. The piping between a “P” trap and the fixture tee or the vented waste line shall be graded 1/4 inch per foot towards the vent and in no event shall have a slope greater than its diameter. The vent opening at fixture tees shall not be below the weir of the “P” trap outlet.
(ii) Trap arm offset. The piping between the “P” trap and vent may change direction or be offset horizontally with the equivalent of no more than 180 degrees total change in direction with a maximum of 90 degrees by any one fitting.
(iii) Concealed traps. Traps with mechanical joints shall be accessible for repair and inspection.
(iv) Removability of traps, etc. Traps shall be designed and installed so the “U” bend is removable without removing the strainers from the fixture. Continuous waste and tail pieces which are permanently attached to the “U” bend shall also be removable without removing the strainer from the fixture.
(b) Cleanout openings —(1) Location of cleanout fittings. (i) Cleanouts shall be installed if the drainage system cannot be cleaned through fixtures, drains, or vents. Cleanouts shall also be provided when fittings of more than 45 degrees are used to affect an offset except where long turn ells are used which provide sufficient “sweep” for cleaning.
(ii) A full size cleanout shall be installed at the upper end of any section of drain piping which does not have the required minimum slope of 1/4 inch per foot grade.
(iii) A cleaning tool shall not be required to pass through more than 360 degrees of fittings, excluding removable “P” traps, to reach any part of the drainage system. Water closets may be removed for drainage system access.
(2) Access to cleanouts. Cleanouts shall be accessible through an unobstructed minimum clearance of 12 inches directly in front of the opening. Each cleanout fitting shall open in a direction opposite to the flow or at right angles to the pipe. Concealed cleanouts that are not provided with access covers shall be extended to a point above the floor or outside of the manufactured home, with pipe and fittings installed, as required, for drainage piping without sags and pockets.
(3) Material. Plugs and caps shall be brass or approved or listed plastic, with screw pipe threads.
(4) Design. Cleanout plugs shall have raised heads except that plugs at floor level shall have counter-sunk slots.
§ 3280.607   Plumbing fixtures.
(a) General requirements —(1) Quality of fixtures. Plumbing fixtures shall have smooth impervious surfaces, be free from defects and concealed fouling surfaces, be capable of resisting road shock and vibration, and shall conform in quality and design to listed standards. Fixtures shall be permanently marked with the manufacturer's name or trademark.
(2) Strainers. The waste outlet of all plumbing fixtures, other than toilets, shall be equipped with a drain fitting that will provide an adequate unobstructed waterway.
(3) Fixture Connections. Fixture tailpieces and continuous wastes in exposed or accessible locations must be of not less than No. 20 Brown and Sharpe gauge seamless drawn-brass tubing or other approved pipe or tubing materials. Inaccessible fixture connections must be constructed according to the requirements for drainage piping. The diameter of each fixture tailpiece, continuous waste, or waste and overflow must be not less than:
(i) 1 1/2 inches, for sinks of two or more compartments, dishwashers, clothes washing machines, laundry tubs, bathtubs, and showers; and
(ii) Not less than 1 1/4 inches for lavatories or single compartment sinks having a 2-inch maximum drain opening.
(4) Concealed connections. Concealed slip joint connections shall be provided with adequately sized unobstructed access panels and shall be accessible for inspection and repair.
(5) Directional fitting. An approved or listed “Y” or other directional-type branch fitting shall be installed in every tailpiece or continuous waste that receives the discharge from food waste disposal units, dishwashing, or other force-discharge fixture or appliance. (See also § 3280.607(b)(4)(ii).)
(6) Water conservation. All lavatory faucets, showerheads, and sink faucets must not exceed a flow of 2.5 gallons per minute (gpm).
(b) Fixtures —(1) Spacing. All plumbing fixtures shall be so installed with regard to spacing as to be reasonably accessible for their intended use.
(2) Water closets. (i) Water closets shall be designed and manufactured according to approved or listed standards and shall be equipped with a water flushing device capable of adequately flushing and cleaning the bowl at each operation of the flushing mechanism.
(ii) Water closet flushing devices shall be designed to replace the water seal in the bowl after each operation. Flush valves, flushometer valves, flushometer tanks and ballcocks shall operate automatically to shut off at the end of each flush or when the tank is filled to operating capacity.
(iii) All water closets must be low consumption (1.6 gallons per flush (gpf)) closets.
(iv) Flush tanks shall be fitted with an overflow pipe large enough to prevent flooding at the maximum flow rate of the ball cock. Overflow pipes shall discharge into the toilet, through the tank.
(v) Floor Connection. Water closets must be securely bolted to an approved flange or other approved fitting that is secured to the floor by means of corrosion-resistant screws. The bolts must be of solid brass or other corrosion-resistant material and must not be less than 1/4 inch in diameter. A watertight seal must be made between the water closet and flange or other approved fitting by use of a gasket, sealing compound, or listed connector device.
(vi) Floor connection. Water closets shall be securely bolted to an approved flange or other approved fitting which is secured to the floor by means of corrosion-resistant screws. The bolts shall be of solid brass or other corrosion-resistant material and shall be not less than one-fourth inch in diameter. A watertight seal shall be made between the water closet and flange or other approved fitting by use of a gasket or sealing compound.
(3) Shower compartment. (i) Each compartment stall shall be provided with an approved watertight receptor with sides and back extending at least 1 inch above the finished dam or threshold. In no case shall the depth of a shower receptor be less than 2 inches or more than 9 inches measured from the top of the finished dam or threshold to the top of the drain. The wall area shall be constructed of smooth, noncorrosive, and nonabsorbent waterproof materials to a height not less than 6 feet above the bathroom floor level. Such walls shall form a watertight joint with each other and with the bathtub, receptor or shower floor. The floor of the compartment shall slope uniformly to the drain at not less than one-fourth nor more than one-half inch per foot.
(ii) The joint around the drain connection shall be made watertight by a flange, clamping ring, or other approved listed means.
(iii) Shower doors and tub and shower enclosures shall be constructed so as to be waterproof and, if glazed, glazing shall comply with the Standard for Safety Glazing Materials used in Buildings—Safety Performance Specifications and Methods of Test, ANSI Z97.1-2004 (incorporated by reference, see § 3280.4).
(iv) Prefabricated plumbing fixtures shall be approved or listed.
(v) Shower and tub-shower combination valves must be balanced pressure, thermostatic, or combination mixing valves that conform to the requirements of ASSE 1016-2005, Performance Requirements for Automatic Compensating Valves for Individual Shower and Tub/Shower Combinations (incorporated by reference, see § 3280.4). Such valves must be equipped with handle position stops that are adjustable in accordance with the valve manufacturer's instructions and to a maximum setting of 120 °F. Hot water supplied to bathtubs and whirlpool bathtubs are to be limited to a temperature of not greater than 120 °F by a water temperature limiting device that conforms to the requirements of ASSE 1070-2004, Performance Requirements for Water Temperature Limiting Devices (incorporated by reference, see § 3280.4).
(4) Dishwashing machines. (i) A dishwashing machine must discharge its waste through a fixed air gap installed above the machine, through a high loop as specified by the dishwashing machine manufacturer, or into an open standpipe receptor with a height greater than the washing compartment of the machine. When a standpipe is used, it must be at least 18 inches, but not more than 30 inches, above the trap weir. The drain connections from the air gap or high loop are permitted to connect to an individual trap to a directional fitting installed in the sink tailpiece or to an opening provided on the inlet side of a food waste disposal unit.
(ii) Drain from a dishwashing machine shall not be connected to a sink tailpiece, continuous waste line, or trap on the discharge side of a food waste disposal unit.
(5) Clothes washing machines. (i) Clothes washing machines shall drain either into a properly vented trap, into a laundry tub tailpiece with watertight connections, into an open standpipe receptor, or over the rim of a laundry tub.
(ii) Standpipes must be either 1 1/2 inch diameter minimum nominal iron pipe size, 1 1/2 inch diameter nominal brass tubing of not less than No. 20 Brown and Sharp gauge, or 1 1/2 inch diameter approved plastic materials. Receptors must discharge into a vented trap or must be connected to a laundry tub appliance by means of an approved or listed directional fitting. Each standpipe must extend not less than 18 inches or more than 42 inches above its trap and must terminate in an accessible location no lower than the top of the clothes washing machine. A removable, tight-fitting cap or plug must be installed on the standpipe when the clothes washer is not provided.
(iii) Clothes washing machine drain shall not be connected to the tailpiece, continuous waste, or trap of any sink or dishwashing machine.
(c) Installation —(1) Access. Each plumbing fixture and standpipe receptor shall be located and installed in a manner to be accessible for usage, cleaning, repair and replacement. Access to diverter valves and other connections from the fixture hardware is not required.
(2) Alignment. Fixtures shall be set level and in true alignment with adjacent walls. Where practical, piping from fixtures shall extend to nearest wall.
(3) Brackets. Wall-hung fixtures shall be rigidly attached to walls by metal brackets or supports without any strain being transmitted to the piping connections. Flush tanks shall be securely fastened to toilets or to the wall with corrosive-resistant materials.
(4) Tub supports. Bathtub rims at wall shall be supported on metal hangers or on end-grain wood blocking attached to the wall unless otherwise recommended by the manufacturer of the tub.
(5) Fixture fittings. Faucets and diverters shall be installed so that the flow of hot water from the fittings corresponds to the left-hand side of the fitting.
(6) Hydromassage bathtub —(i) Access panel. A door or panel of sufficient size must be installed to provide access to the pump for repair or replacement.
(ii) Piping drainage. The circulation pump must be accessibly located above the crown weir of the trap. The pump drain line must be properly sloped to drain the volute after fixture use.
(iii) Piping. Hydromassage bathtub circulation piping must be installed to be self-draining.
(iv) Electrical. Wiring must comply with Articles 680.70, 680.71, and 680.72 of the National Electrical Code, NFPA No. 70-2005.
§ 3280.608   Hangers and supports.
(a) Strains and stresses. Piping in a plumbing system shall be installed without undue strains and stresses, and provision shall be made for expansion, contraction, and structural settlement.
(b) Piping supports. Piping must be secured at sufficiently close intervals to keep the pipe in alignment and carry the weight of the pipe and contents. Unless otherwise stated in the standards incorporated by reference for specific materials at § 3280.604(a), or unless specified by the pipe manufacturer, horizontal plastic drainage piping must be supported at intervals not to exceed 4 feet and horizontal plastic water piping must be supported at intervals not to exceed 3 feet. Vertical drainage and water piping must be supported at each story height.
(c) Hangers and anchors. (1) Hangers and anchors shall be of sufficient strength to support their proportional share of the pipe alignments and prevent rattling.
(2) Piping shall be securely attached to the structure by hangers, clamps, or brackets which provide protection against motion, vibration, road shock, or torque in the chassis.
(3) Hangers and straps supporting plastic pipe shall not compress, distort, cut or abrade the piping and shall allow free movement of the pipe.
§ 3280.609   Water distribution systems.
(a) Water supply —(1) Supply piping. Piping systems shall be sized to provide an adequate quantity of water to each plumbing fixture at a flow rate sufficient to keep the fixture in a clean and sanitary condition without any danger of backflow or siphonage. (See table in § 3280.609(f)(1)). The manufacturer shall include in his written installation instructions that the manufactured home has been designed for an inlet water pressure of 80 psi, and a statement that when the manufactured home is to be installed in areas where the water pressure exceeds 80 psi, a pressure reducing valve should be installed.
(2) Hot water supply. Each manufactured home equipped with a kitchen sink, and bathtub and/or shower shall be provided with a hot water supply system including a listed water heater.
(b) Water outlets and supply connections —(1) Water connection. Each manufactured home with a water distribution system shall be equipped with a 3/4 inch threaded inlet connection. This connection shall be tagged or marked “Fresh Water Connection” (or marked “Fresh Water Fill”). A matching cap or plug shall be provided to seal the water inlet when it is not in use, and shall be permanently attached to the manufactured home or water supply piping. When a master cold water shutoff full flow valve is not installed on the main feeder line in an accessible location, the manufacturer's installation instructions shall indicate that such a valve is to be installed in the water supply line adjacent to the home. When a manufactured home includes expandable rooms or is composed of two or more units, fittings or connectors designed for such purpose shall be provided to connect any water piping. When not connected, the water piping shall be protected by means of matching threaded caps or plugs.
(2) Prohibited connections. (i) The installation of potable water supply piping or fixture or appliance connections shall be made in a manner to preclude the possibility of backflow.
(ii) No part of the water system shall be connected to any drainage or vent piping.
(3) Rim outlets. The outlets of faucets, spouts, and similar devices shall be spaced at least 1 inch above the flood level of the fixture.
(4) Appliance connections. Water supplies connected to clothes washing or dishwashing machines shall be protected by an approved or listed fixed air gap provided within the appliance by the manufacturer.
(5) Flushometer valves or manually operated flush valves. An approved or listed vacuum breaker shall be installed and maintained in the water supply line on the discharge side of a water closet flushometer valve or manually operated flush valve. Vacuum breakers shall have a minimum clearance of 6 inches above the flood level of the fixture to the critical level mark unless otherwise permitted in their approval.
(6) Flush tanks. Water closet flush tanks shall be equipped with an approved or listed anti-siphon ball cock which shall be installed and maintained with its outlet or critical level mark not less than 1 inch above the full opening of the overflow pipe.
(7) Hose bibbs. When provided, all exterior hose bibbs and laundry sink hose connections must be protected by a listed nonremovable backflow prevention device. This requirement is not applicable to hose connections provided for automatic washing machines with built-in backflow prevention or water heater drain valves.
(8) Flushometer tanks. Flushometer tanks must be equipped with an approved air gap or vacuum breaker assembly that is located above the flood-level rim above the fixture.
(c) Water heater safety devices —(1) Relief valves. (i) All water heaters shall be installed with approved and listed fully automatic valve or valves designed to provide temperature and pressure relief.
(ii) Any temperature relief valve or combined pressure and temperature relief valve installed for this purpose shall have the temperature sensing element immersed in the hottest water within the upper 6 inches of the tank. It shall be set to start relieving at a pressure of 150 psi or the rated working pressure of the tank whichever is lower and at or below a water temperature of 210 °F.
(iii) Relief valves must be provided with full-sized drains, with cross sectional areas equivalent to that of the relief valve outlet. The outlet of a pressure relief valve, temperature relief valve, or combination thereof, must not be directly connected to the drainage system. The discharge from the relief valve must be piped full size separately to the exterior of the manufactured home, not underneath the home, or to an indirect waste receptor located inside the manufactured home. Exterior relief drains shall be directed down and shall terminate between 6″ and 24″ above finished grade. Drain lines must be of a material listed for hot water distribution and must drain fully by gravity, must not be trapped, and must not have their outlets threaded, and the end of the drain must be visible for inspection.
(iv) Relief valve piping designed to be located underneath the manufactured home is not required to be installed at the factory provided the manufacturer designs the system for site assembly and also provides all materials and components including piping, fittings, cement, supports, and instructions for proper site installation.
(d) Materials —(1) Piping material. Water pipe shall be of standard weight brass, galvanized wrought iron, galvanized steel, Type K, L or M copper tubing, approved or listed plastic or other approved or listed material.
(i) Plastic piping. All plastic water piping and fittings in manufactured homes must be listed for use with hot water.
(ii) [Reserved]
(2) Fittings. Appropriate fittings shall be used for all changes in size and where pipes are joined. The material and design of fittings shall conform to the type of piping used. Special consideration shall be given to prevent corrosion when dissimilar metals are joined.
(i) Fittings for screw piping shall be standard weight galvanized iron for galvanized iron and steel pipe, and of brass for brass piping. They shall be installed where required for change in direction, reduction of size, or where pipes are joined together.
(ii) Fittings for copper tubing shall be cast brass or drawn copper (sweat-soldered) or shall be approved or listed fittings for the purpose intended.
(3) Prohibited material. Used piping materials shall not be permitted. Those pipe dopes, solder, fluxes, oils, solvents, chemicals, or other substances that are toxic, corrosive, or otherwise detrimental to the water system shall not be used. In addition, for those manufactured homes to be connected to a public water system, all water piping shall be lead-free (as defined in section 109(c)(2) of the Safe Drinking Water Act Amendments of 1986) with solders and flux containing not more than 0.2 percent lead and pipes and pipe fittings containing not more than 8.0 percent lead.
(e) Installation of piping —(1) Minimum requirement. All piping equipment, appurtenances, and devices shall be installed in workmanlike manner and shall conform with the provisions and intent of this standard.
(2) Screw pipe. Iron pipe-size brass or galvanized iron or steel pipe fittings shall be joined with approved or listed standard pipe threads fully engaged in the fittings. Pipe ends shall be reamed to the full bore of the pipe. Pipe-joint compound shall be insoluble in water, shall be nontoxic and shall be applied to male threads only.
(3) Solder fittings. Joints in copper water tubes shall be made by the appropriate use of approved cast brass or wrought copper fittings, properly soldered together. The surface to be soldered shall be thoroughly cleaned bright mechanically. The joints shall be properly fluxed and made with a solder that contains no more than 0.2 percent lead.
(4) Flared fittings. A flaring tool shall be used to shape the ends of flared tubing to match the flare of fittings.
(5) Plastic pipe and fittings. Plastic pipe and fittings shall be joined by installation methods recommended by the manufacturer or in accordance with provisions of a listed standard.
(f) Size of water supply piping —(1) Minimum size. The size of water supply piping and branch lines shall not be less than sizes shown in the following table:
Minimum Size Tubing and Pipe for Water Distribution Systems
*6 ft maximum length.
(2) Sizing procedure. Both hot and cold water piping systems shall be computed by the following method:
(i) Size of branch. Start at the most remote outlet on any branch of the hot or cold water piping and progressively count towards the water service connection, computing the total number of fixtures supplied along each section of piping. Where branches are joined together, the number of fixtures on each branch shall be totalled so that no fixture is counted twice. Following down the left-hand column of the preceding table a corresponding number of fixtures will be found. The required pipe or tubing size is indicated in the other columns on the same line.
(ii) A water heater, food waste disposal unit, evaporative cooler or ice maker shall not be counted as a water-using fixture when computing pipe sizes.
(g) Line valves. Valves, when installed in the water supply distribution system (except those immediately controlling one fixture supply) and when fully opened, shall have a cross-sectional area of the smallest orifice or opening, through which the water flows, at least equal to the cross-sectional area of the nominal size of the pipe in which the valve is installed.
§ 3280.610   Drainage systems.
(a) General. (1) Each fixture directly connected to the drainage system shall be installed with a water seal trap (§ 3280.606(a)).
(2) The drainage system shall be designed to provide an adequate circulation of air in all piping with no danger of siphonage, aspiration, or forcing of trap seals under conditions of ordinary use.
(b) Materials —(1) Pipe. Drainage piping must be standard weight galvanized steel, brass, copper tube DWV, listed Scheduled 40 ABS plastic, listed Scheduled 40 PVC plastic, cast iron, or other listed or approved materials.
(2) Fittings. Drainage fittings shall be recessed drainage pattern with smooth interior waterways of the same diameter as the piping and shall be of a material conforming to the type of piping used. Drainage fittings shall be designed to provide for a 1/4 inch per foot grade in horizontal piping.
(i) Fittings for screw pipe shall be cast iron, malleable iron, brass, or listed plastic with standard pipe threads.
(ii) Fittings for copper tubing shall be cast brass or wrought copper.
(iii) Socket-type fittings for plastic piping shall comply with listed standards.
(iv) Brass or bronze adaptor or wrought copper fittings shall be used to join copper tubing to threaded pipe.
(c) Drain outlets. (1) General. Each manufactured home shall have only one drain outlet.
(2) Clearance from drain outlet. The drain outlet shall be provided with a minimum clearance of 3 inches in any direction from all parts of the structure or appurtenances and with not less than 18 inches unrestricted clearance directly in front of the drain outlet.
(3) Drain connector. The drain connector shall not be smaller than the piping to which it is connected and shall be equipped with a water-tight cap or plug matching the drain outlet. The cap or plug shall be permanently attached to the manufactured home or drain outlet.
(4) Size Requirement. The drain outlet and drain connector shall not be less than 3 inches inside diameter.
(5) Preassembly of drain lines. Section(s) of the drain system, designed to be located underneath the manufactured home or between stories of the manufactured home, are not required to be factory installed when the manufacturer designs the system for site assembly and also provides all materials and components, including piping, fittings, cement, supports, and instructions necessary for proper site installation.
(d) Fixture connections. Drainage piping shall be provided with approved or listed inlet fittings for fixture connections, correctly located according to the size and type of fixture to be connected.
(1) Water closet connection. The drain connection for each water closet shall be 3 inches minimum inside diameter and shall be fitted with an iron, brass, or listed plastic floor flange adaptor ring securely screwed, soldered or otherwise permanently attached to the drain piping, in an approved manner and securely fastened to the floor.
(2) [Reserved]
(e) Size of drainage piping. Fixture drains must be sized as follows:
(1) Fixture drains serving a single lavatory must be a minimum of 1 1/4 inches in diameter.
(2) Fixture drains serving two or three fixtures must be a minimum of 1 1/2 inches in diameter.
(3) Fixture drains serving four or more fixtures that are individually vented must be a minimum of 2 inches in diameter.
(4) Fixture drains for water closets must be a minimum of 3 inches in diameter.
(f) Wet-vented drainage system. Plumbing fixture traps may connect into a wet-vented drainage system which shall be designed and installed to accommodate the passage of air and waste in the same pipe.
(1) Horizontal piping. All parts of a wet-vented drainage system, including the connected fixture drains, shall be horizontal except for wet-vented vertical risers which shall terminate with a 1 1/2 inch minimum diameter continuous vent. Where required by structural design, wet-vented drain piping may be offset vertically when other vented fixture drains or relief vents are connected to the drain piping at or below the vertical offsets.
(2) Size. A wet-vented drain pipe shall be 2 inches minimum diameter and at least one pipe size larger than the largest connected trap or fixture drain. Not more than three fixtures may connect to a 2-inch diameter wet-vented drain system.
(3) Length of trap arm. Fixture traps shall be located within the distance given in § 3280.611(c)(5). Not more than one trap shall connect to a trap arm.
(g) Offsets and branch fittings —(1) Changes in direction. Changes in direction of drainage piping shall be made by the appropriate use of approved or listed fittings, and shall be of the following angles: 11 1/4 , 22 1/2 , 45, 60, or 90 degrees; or other approved or listed fittings or combinations of fittings with equivalent radius or sweep.
(2) Horizontal to vertical. Horizontal drainage lines, connecting with a vertical pipe shall enter through 45-degree “Y” branches, 60-degree “Y” branches, long-turn “TY” branches, sanitary “T” branches, or other approved or listed fittings or combination of fittings having equivalent sweep. Fittings having more than one branch at the same level shall not be used, unless the fitting is constructed so that the discharge from any one branch cannot readily enter any other branch. However, a double sanitary “T” may be used when the drain line is increased not less than two pipe sizes.
(3) Horizontal to horizontal and vertical to horizontal. Horizontal drainage lines connecting with other horizontal drainage lines or vertical drainage lines connected with horizontal drainage lines shall enter through 45-degree “Y” branches, long-turn “TY” branches, or other approved or listed fittings or combination of fittings having equivalent sweep.
(h) Grade of horizontal drainage piping. Except for fixture connections on the inlet side of the trap, horizontal drainage piping shall be run in practical alignment and have a uniform grade of not less than 1/4 inch per foot toward the manufactured home drain outlet. Where it is impractical, due to the structural features or arrangement of any manufactured home, to obtain a grade of 1/4 inch per foot, the pipe or piping may have a grade of not less than 1/8 inch per foot, when a full size cleanout is installed at the upper end.
§ 3280.611   Vents and venting.
(a) General. Each plumbing fixture trap shall be protected against siphonage and back pressure, and air circulation shall be ensured throughout all parts of the drainage system by means of vents installed in accordance with the requirements of this section and as otherwise required by this standard.
(b) Materials —(1) Pipe. Vent piping must be standard weight galvanized steel, brass, copper tube DWV, listed Scheduled 40 ABS plastic, listed Scheduled 40 PVC plastic, cast iron, or other listed or approved materials.
(2) Fittings. Appropriate fittings shall be used for all changes in direction or size and where pipes are joined. The material and design of vent fittings shall conform to the type of piping used.
(i) Fittings for screw pipe shall be cast iron, malleable iron, plastic, or brass, with standard pipe threads.
(ii) Fittings for copper tubing shall be cast brass or wrought copper.
(iii) Fittings for plastic piping shall be made to approved applicable standards.
(iv) Brass adaptor fittings or wrought copper shall be used to join copper tubing to threaded pipe.
(v) Listed rectangular tubing may be used for vent piping only providing it has an open cross section at least equal to the circular vent pipe required. Listed transition fittings shall be used.
(c) Size of vent piping —(1) Main vent. The drain piping for each toilet shall be vented by a 1 1/2 inch minimum diameter vent or rectangular vent of venting cross section equivalent to or greater than the venting cross section of a 1 1/2 inch diameter vent, connected to the toilet drain by one of the following methods:
(i) A 1 1/2 inch diameter (min.) individual vent pipe or equivalent directly connected to the toilet drain within the distance allowed in § 3280.611(c)(5), for 3-inch trap arms undiminished in size through the roof;
(ii) A 1 1/2 -inch diameter (min.) continuous vent or equivalent, indirectly connected to the toilet drain piping within the distance allowed in paragraph (c)(5) of this section for 3 inch trap arms through a 2-inch wet vented drain that carries the waste of not more than one fixture. Sections of the wet vented drain that are 3 inches in diameter are permitted to carry the waste of an unlimited number of fixtures; or
(iii) Two or more vented drains when at least one is wet-vented, or 2-inch diameter (minimum), and each drain is separately connected to the toilet drain. At least one of the drains shall connect within the distance allowed in § 3280.611(c)(5) for 3-inch trap arms.
(2) Vent pipe areas. Each individually vented fixture with a 1 1/2 inch or smaller trap shall be provided with a vent pipe equivalent in area to a 1 1/4 inch nominal pipe size. The main vent, toilet vent and relief vent, and the continuous vent of wet-vented systems shall have an area equivalent to 1 1/2 inch nominal pipe size.
(3) Common vent. When two fixture traps located within the distance allowed from their vent have their trap arms connected separately at the same level into an approved double fitting, an individual vent pipe may serve as a common vent without any increase in size.
(4) Intersecting vents. Where two or more vent pipes are joined together, no increase in size shall be required; however, the largest vent pipe shall extend full size through the roof.
(5) Distance of fixture trap from vent shall not exceed the values given in the following table:
Maximum Distance of Fixtures From Vent Trap
(d) Mechanical Vents. Where mechanical vents are used as a secondary vent system for plumbing fixtures that are protected by traps, the mechanical vents must comply with paragraphs (d)(1) or (2) of this section.
(1) Spring-operated mechanical (anti-siphon) vents must comply with the following:
(i) No more than two fixtures individually protected by the spring-operated mechanical vent may be drained by a common 1 1/2 inch diameter drain.
(ii) The drain size for three or more fixtures individually protected by a spring-operated mechanical vent must be at least 2 inches in diameter.
(iii) Spring-operated mechanical vents are restricted to venting fixtures with 1 1/2 inch traps.
(iv) A spring-operated mechanical vent must be installed in a location that allows a free flow of air and is accessible for inspection, maintenance, and replacement. The sealing function must be at least 6 inches above the top of the trap arm.
(v) Materials for the spring-operated mechanical vents must be as follows:
(A) Cap and housing must be listed acrylonitrile-butadiene-styrene, DWV grade;
(B) Stem must be DWV grade nylon or acetal;
(C) Spring must be stainless steel wire, Type 302; and
(D) Sealing disc must be either:
( 1 ) Neoprene, conforming to CISPI-HSN-85, Specification for Neoprene Rubber Gaskets for HUB and Spigot Cast Iron Soil Pipe and Fittings (incorporated by reference, see § 3280.4), and to ASTM C564-97, Standard Specification for Rubber Gaskets for Cast Iron Soil Pipe and Fittings (incorporated by reference, see § 3280.4); or
( 2 ) Other material, conforming to ASTM C920-02, Standard Specification for Elastomeric Joint Sealants (incorporated by reference, see § 3280.4), and to ASTM D4635-01, Standard Specification for Polyethylene Films Made from Low-Density Polyethylene for General Use and Packaging Applications (incorporated by reference, see § 3280.4).
(2) Gravity-operated mechanical (air admittance valves) vents must comply with the following:
(i) Where installed to vent any fixture, the drain system must have a minimum 1 1/2 inch diameter vent that terminates outside the manufactured home.
(ii) Where gravity-operated mechanical vent devices terminate in the attic cavity, the following requirements must be met:
(A) The attic cavity must be accessible;
(B) The sealing device must be installed a minimum of 6 inches above the insulation materials; and
(C) The attic must be vented in accordance with § 3280.504(c)(1)(i);
(3) Mechanical vents must be installed in accordance with the vent manufacturer's instructions.
(e) Grade and connections —(1) Horizontal vents. Each vent shall extend vertically from its fixture “T” or point of connection with the waste piping to a point not less than 6 inches above the extreme flood level of the fixture it is venting before offsetting horizontally or being connected with any other vent pipe. Vents for horizontal drains shall connect above the centerline of the drain piping ahead (downstream) of the trap. Where required by structural conditions, vent piping may offset below the rim of the fixture at the maximum angle or height possible.
(f) Vent terminal. Vents must terminate through the roof or wall, or to a mechanical vent device in accordance with paragraph (d) of this section.
(1) Roof extension. Each vent pipe must extend through its flashing and terminate vertically. Vents that extend through the roof must extend undiminished in size, not less than 2 inches above the roof. Vent openings must be at least 3 feet away from any motor-driven air intake that opens into any habitable area.
(2) Wall extensions. Extensions through exterior walls must terminate downward, have a screen to prevent entrance of birds and rodents, and be located as follows:
(i) Extensions must not be located beneath a door, window, or other opening;
(ii) Extensions must be a minimum of 10 feet above the finished floor;
(iii) Extensions must be located a minimum of 2 feet above any building opening that is within 10 feet horizontally of any extension; and
(iv) Extensions must not terminate under an overhang with soffit vents.
(3) Flashing. The opening around each vent pipe shall be made watertight by an adequate flashing or flashing material.
(g) Vent caps. Vent caps, if provided, shall be of the removable type (without removing the flashing from the roof). When vent caps are used for roof space ventilation and the caps are identical to vent caps used for the plumbing system, plumbing system caps shall be identified with permanent markings.
§ 3280.612   Tests and inspection.
(a) Water system. All water piping in the water distribution system must be subjected to a pressure test. The test must be made by subjecting the system to air or water at 80 psi + or − 5 psi for 15 minutes without loss of pressure. The water used for the test must be obtained from a potable water source.
(b) Drainage and vent system and plumbing fixtures. The waste and vent system shall be tested by one of the three following alternate methods for evidence or indication of leakage:
(1) Water test. Before plumbing fixtures are connected, all of the openings into the piping shall be plugged and the entire piping system subjected to a static water test for 15 minutes by filling it with water to the top of the highest vent opening. There shall be no evidence of leakage.
(2) Air test. After all fixtures have been installed, the traps filled with water, and the remaining openings securely plugged, the entire system shall be subjected to a 2-inch (manometer) water column air pressure test. If the system loses pressure, leaks may be located with smoke pumped into the system, or with soap suds spread on the exterior of the piping (Bubble test).
(3) Flood level test. The manufactured home shall be in a level position, all fixtures shall be connected, and the entire system shall be filled with water to the rim of the water closet bowl. (Tub and shower drains shall be plugged). After all trapped air has been released, the test shall be sustained for not less than 15 minutes without evidence of leaks. Then the system shall be unplugged and emptied. The waste piping above the level of the water closet bowl shall then be tested and show no indication of leakage when the high fixtures are filled with water and emptied simultaneously to obtain the maximum possible flow in the drain piping.
(c) Fixture test. The plumbing fixtures and connections shall be subjected to a flow test by filling them with water and checking for leaks and retarded flow while they are being emptied.
(d) Shower compartments. Shower compartments and receptors shall be tested for leaks prior to being covered by finish material. Each pan shall be filled with water to the top of the dam for not less than 15 minutes without evidence of leakage.
§ 3280.701   Scope.
Subpart H of this standard covers the heating, cooling and fuel burning equipment installed within, on, or external to a manufactured home.
§ 3280.702   Definitions.
The definitions in this subpart apply to subpart H only.
Accessible, when applied to a fixture, connection, appliance or equipment, means having access thereto, but which may require the removal of an access panel, door or similar obstruction.
Air conditioner blower coil system means a comfort cooling appliance where the condenser section is placed external to the manufactured home and evaporator section with circulating blower attached to the manufactured home air supply duct system. Provision must be made for a return air system to the evaporator/blower section. Refrigerant connection between the two parts of the system is accomplished by tubing.
Air conditioner split system means a comfort cooling appliance where the condenser section is placed external to the manufactured home and the evaporator section incorporated into the heating appliance or with a separate blower/coil section within the manufactured home. Refrigerant connection between the two parts of the system is accomplished by tubing.
Air conditioning condenser section means that portion of a refrigerated air cooling or (in the case of a heat pump) heating system which includes the refrigerant pump (compressor) and the external heat exchanger.
Air conditioning evaporator section means a heat exchanger used to cool or (in the case of a heat pump) heat air for use in comfort cooling (or heating) the living space.
Air conditioning self contained system means a comfort cooling appliance combining the condenser section, evaporator and air circulating blower into one unit with connecting ducts for the supply and return air systems.
Air duct means conduits or passageways for conveying air to or from heating, cooling, air conditioning or ventilation equipment, but not including the plenum.
Automatic pump (oil lifter) means a pump, not an integral part of the oil-burning appliance, that automatically pumps oil from the supply tank and delivers the oil under a constant head to an oil-burning appliance.
Btu. British thermal units means the quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit.
Btuh means British thermal units per hour.
Burner means a device for the final conveyance of fuel or a mixture of fuel and air to the combustion zone.
Central air conditioning system means either an air conditioning split system or an external combination heating/cooling system.
Class 0 air ducts and air connectors means air ducts and air connectors having a fire hazard classification of zero when tested in accordance with UL 181-2003, Factory-Made Air Ducts and Air Connectors (incorporated by reference, see § 3280.4).
Class 1 air ducts and air connectors means air ducts and air connectors having a flame spread rating of not over 25 without evidence of continued progressive combustion and a smoke developed rating of not over 50 when tested in accordance with UL 181-2003, Standard for Safety Factory-Made Air Ducts and Air Connectors (incorporated by reference, see § 3280.4).
Clearance means the distance between the appliance, chimney, vent, chimney or vent connector or plenum and the nearest surface.
Combination space heating and water heating appliance means a listed unit that is designed to provide space heating and water heating from a single primary energy source.
Connector-Gas appliance: means a flexible or semi-rigid connector used to convey fuel gas between a gas outlet and a gas appliance.
Direct-vent system means a system or method of construction where all air for combustion is derived directly from the outside atmosphere and all flue gases are discharged to the outside atmosphere.
Direct-vent system appliance means an appliance that is installed with a direct vent system.
External combination heating/cooling system means a comfort conditioning system placed external to the manufactured home with connecting ducts to the manufactured home for the supply and return air systems.
Factory-built fireplace means a hearth, fire chamber and chimney assembly composed of listed factory-built components assembled in accordance with the terms of listing to form a complete fireplace.
Fireplace stove means a chimney connected solid fuel-burning stove having part of its fire chamber open to the room.
Fuel gas piping system means the arrangement of piping, tubing, fittings, connectors, valves and devices designed and intended to supply or control the flow of fuel gas to the appliance(s).
Fuel oil piping system means the arrangement of piping, tubing, fittings, connectors, valves and devices designed and intended to supply or control the flow of fuel oil to the appliance(s).
Gas clothes dryer means a device used to dry wet laundry by means of heat derived from the combustion of fuel gases.
Gas refrigerator means a gas-burning appliance which is designed to extract heat from a suitable chamber.
Gas supply connection means the terminal end or connection to which a gas supply connector is attached.
Gas supply connector, manufactured home means a listed flexible connector designed for connecting the manufactured home to the gas supply source.
Gas vents means factory-built vent piping and vent fittings listed by an approved testing agency, that are assembled and used in accordance with the terms of their listings, for conveying flue gases to the outside atmosphere.
(1) Type B gas vent means a gas vent for venting gas appliances with draft hoods and other gas appliances listed for use with Type B gas vents.
(2) Type BW gas vent means a gas vent for venting listed gas-fired vented wall furnaces.
Heat producing appliance means all heating and cooking appliances and fuel burning appliances.
Heating appliance means an appliance for comfort heating, domestic water heating, or a combination of comfort heating and domestic water heating.
Liquefied petroleum gases. The terms Liquefied petroleum gases, LPG and LP-Gas as used in this standard shall mean and include any material which is composed predominantly of any of the following hydrocarbons, or mixtures of them: propane, propylene butanes (normal butane or isobutane), and butylenes.
Plenum means an air compartment which is part of an air-distributing system, to which one or more ducts or outlets are connected.
(1) Furnace supply plenum is a plenum attached directly to, or an integral part of, the air supply outlet of the furnace.
(2) Furnace return plenum is a plenum attached directly to, or an integral part of, the return inlet of the furnace.
Quick-disconnect device means a hand-operated device which provides a means for connecting and disconnecting a gas supply or connecting gas systems and which is equipped with an automatic means to shut off the gas supply when the device is disconnected.
Readily accessible means direct access without the necessity of removing any panel, door, or similar obstruction.
Roof jack means that portion of a manufactured home heater flue or vent assembly, including the cap, insulating means, flashing, and ceiling plate, located in and above the roof of a manufactured home.
Sealed combustion system appliance means an appliance which by its inherent design is constructed so that all air supplied for combustion, the combustion system of the appliance, and all products of combustion are completely isolated from the atmosphere of the space in which it is installed.
Water heater means an appliance for heating water for domestic purposes.
§ 3280.703   Minimum standards.
Heating, cooling and fuel burning appliances and systems in manufactured homes shall be free of defects, and shall conform to applicable standards in the following table unless otherwise specified in this standard. (See § 3280.4) When more than one standard is referenced, compliance with any one such standard shall meet the requirements of this standard.
Decorative Gas Appliances for Installation in Solid Fuel Burning Fireplaces—RADCO DS-010-91 (incorporated by reference, see § 3280.4).
Standard Specification for Seamless Copper Tube for Air Conditioning and Refrigeration Field Service—ASTM B280-95a.
Factory-Made Air Ducts and Air Connectors, UL 181, Ninth Edition, April 4, 1996, with revisions through May 15, 2003 (incorporated by reference, see § 3280.4).
Relief Valves for Hot Water Supply Systems, ANSI Z21.22-1999, (incorporated by reference, see § 3280.4).
Gas Appliance Thermostats—ANSI Z21.23-93 (incorporated by reference, see § 3280.4).
Standard for the Installation of Oil-Burning Equipment, NFPA 31-01 (incorporated by reference, see § 3280.4).
§ 3280.704   [Reserved]
§ 3280.705   Gas piping systems.
(a) General. The requirements of this section shall govern the installation of all fuel gas piping attached to any manufactured home. The gas piping supply system shall be designed for a pressure not exceeding 14 inch water column ( 1/2 psi) and not less than 7 inch water column ( 1/4 psi). The manufacturer shall indicate in his written installation instructions the design pressure limitations for safe and effective operation of the gas piping system. None of the requirements listed in this section shall apply to the piping supplied as a part of an appliance. All exterior openings around piping, ducts, plenums or vents shall be sealed to resist the entrance of rodents.
(b) Materials. All materials used for the installation, extension, alteration, or repair of any gas piping system shall be new and free from defects or internal obstructions. It shall not be permissible to repair defects in gas piping or fittings. Inferior or defective materials shall be removed and replaced with acceptable material. The system shall be made of materials having a melting point of not less than 1,450 F, except as provided in § 3280.705(e). They shall consist of one or more of the materials described in § 3280.705(b) (1) through (4).
(1) Steel or wrought-iron pipe shall comply with ANSI Standard B36.10-1979, Welded and Seamless Wrought Steel Pipe. Threaded brass pipe in iron pipe sizes may be used. Threaded brass pipe shall comply with ASTM B43-91, Standard Specification for Seamless Red Brass Pipe, Standard Sizes.
(2) Fittings for gas piping shall be wrought iron, malleable iron, steel, or brass (containing not more than 75 percent copper).
(3) Copper tubing must be annealed type, Grade K or L, conforming to the Standard Specification for Seamless Copper Water Tube, ASTM B88-93, or must comply with the Standard Specification for Seamless Copper Tube for Air Conditioning and Refrigeration Service, ASTM B280-1995. Copper tubing must be internally tinned.
(4) Steel tubing must have a minimum wall thickness of 0.032 inch for tubing of 1/2 inch diameter and smaller and 0.049 inch for diameters 1/2 inch and larger. Steel tubing must be in accordance with ASTM Standard Specification for Electric-Resistance-Welded Coiled Steel Tubing for Gas and Fuel Oil Lines, ASTM A539-1999, and must be externally corrosion protected.
(5) Corrugated stainless steel tubing (CSST) systems must be listed and installed in accordance with ANSI/IAS LC-1-1997, Fuel Gas Piping Systems Using Corrugated Stainless Steel Tubing (CSST) (incorporated by reference, see § 3280.4), and the requirements of this section.
(c) Piping design. Each manufactured home requiring fuel gas for any purpose shall be equipped with a natural gas piping system acceptable for LP-gas. Where fuel gas piping is to be installed in more than one section of an expandable or multiple unit home, the design and construction of the crossover(s) shall be as follows:
(1) All points of crossover beneath the transportable sections must be readily accessible from the exterior of the home. In multi-story manufactured homes, the interconnections between stories must be accessible through a panel on the exterior or interior of the manufactured home.
(2) The connection(s) between units must be made with a connector(s) listed for exterior use or direct plumbing sized in accordance with § 3280.705(d). A shutoff valve of the non-displaceable rotor type conforming to ANSI Z21.15-1997, Manually Operated Gas Valves for Appliances, Appliances Connector Valves, and Hose End Valves, suitable for outdoor use must be installed at each crossover point upstream of the connection.
(3) The connection(s) may be made by a listed quick disconnect device which shall be designed to provide a positive seal of the supply side of the gas system when such device is separated.
(4) The flexible connector, direct plumbing pipe, or “quick disconnect” device shall be provided with protection from mechanical and impact damage and located to minimize the possibility of tampering.
(5) For gas line cross over connections made with either hard pipe or flexible connectors, the crossover point(s) shall be capped on the supply side to provide a positive seal and covered on the other side with a suitable protective covering.
(6) Suitable protective coverings for the connection device(s) when separated, shall be permanently attached to the device or flexible connector.
(7) When a quick disconnect device is installed, a 3 inch by 1 3/4 inch minimum size tag made of etched, metal-stamped or embossed brass, stainless steel, anodized or alcalde aluminum not less than 0.020 inch thick or other approved material (e.g., 0.005 inch plastic laminates) shall be permanently attached on the exterior wall adjacent to the access to the “quick disconnect” device. Each tag shall be legibly inscribed with the following information using letters no smaller than 1/4 inch high:
(d) Gas pipe sizing. Gas piping systems shall be sized so that the pressure drop to any appliance inlet connection from any gas supply connection, when all appliances are in operation at maximum capacity, is not more than 0.5 inch water column as determined on the basis of test, or in accordance with table 3280.705(d). When determining gas pipe sizing in the table, gas shall be assumed to have a specific gravity of 0.65 and rated at 1000 B.T.U. per cubic foot. The natural gas supply connection(s) shall be not less than the size of the gas piping but shall be not smaller than 3/4 inch nominal pipe size.
Table to paragraph ( d )—Maximum Capacity of Different Sizes of Pipe and Tubing in Thousands of Btu/hr of Natural Gas for Gas Pressures of 0.5 psig or Less, and a Maximum Pressure Drop of 1/2 in. Water Column
1 Includes losses for four 90-degree bends and two end fittings. Tubing runs with larger numbers of bend and/or fittings shall be increased by an equivalent length of tubing according to the following equation: L = 1.3 n, where L is actual length (ft) of tubing and n is the number of additional fittings and/or bends.
2 EHD (Equivalent Hydraulic Diameter)—A measure of the hydraulic efficiency between different tubing sizes.
(e) Joints for gas pipe. All pipe joints in the piping system, unless welded or brazed, shall be threaded joints that comply with Pipe Threads, General Purpose (Inch), adopted 25 October 1984, ANSI/ASME B1.20.1-1983. Right and left nipples or couplings shall not be used. Unions, if used, shall be of ground joint type. The material used for welding or brazing pipe connections shall have a melting temperature in excess of 1,000 F.
(f) Joints for tubing. (1) Tubing joints shall be made with either a single or a double flare of 45 degrees in accordance with Flares For Tubing, SAE-J533b-1992 or with other listed vibration-resistant fittings, or joints may be brazed with material having a melting point exceeding 1,000 °F. Metallic ball sleeve compression-type tubing fittings shall not be used.
(2) Steel tubing joints shall be made with a double-flare in accordance with Flares For Tubing, SAE-J533b-1972.
(g) Pipe joint compound. Screw joints shall be made up tight with listed pipe joint compound, insoluble in liquefied petroleum gas, and shall be applied to the male threads only.
(h) Concealed tubing. (1) Copper tubing must not be run inside walls, floors, partitions, or roofs. Corrugated stainless steel tubing (CSST) may be run inside walls, floors, partitions, and roofs under the following conditions:
(i) The CSST is protected from accidental puncture by a steel strike barrier not less than 0.058 inch thick, or the barrier's equivalent, installed between the tubing and the finished wall and extending 4 inches beyond concealed penetrations of plates, firestops, and wall studs, or specified by the tubing manufacturer's instructions; and
(ii) The CSST is installed in single runs and is not rigidly secured.
(2) Where tubing passes through exterior walls, floors, partitions, or similar construction, the tubing must be protected by the use of weather-resistant grommets that snugly fit both the tubing and the hole through which the tubing passes, or protected as specified in the tubing manufacturer's instructions.
(3) Concealed joints: Piping or tubing joints must not be located in any wall, floor, partition, or similar concealed construction space.
(i) Concealed joints. Piping or tubing joints shall not be located in any floor, wall partition, or similar concealed construction space.
(j) Gas supply connections. When gas appliances are installed, at least one gas supply connection must be provided on each home. The connection must not be located beneath an exit door. Where more than one connection is provided, the piping system must be sized to provide adequate capacity from each supply connection.
(k) Identification of gas supply connections. Each manufactured home must have permanently affixed to the exterior skin at or near each gas supply connection or the end of the pipe, a tag of 3 inches by 1 3/4 inches minimum size, made of etched, metal-stamped or embossed brass, stainless steel, anodized or alcalde aluminum not less than 0.020 inch thick, or other approved material [ e.g., 0.005 inch plastic laminates], with the information shown in Figure 1 to this paragraph (k). The connector capacity indicated on this tag must be equal to or greater than the total Btu/hr rating of all intended gas appliances.
(l) LP-gas supply connectors. (1) A listed LP-Gas flexible connection conforming to UL 569-1995, Pigtails and Flexible Hose Connectors for LP Gas, or equal must be supplied when LP-Gas cylinders(s) and regulator(s) are supplied.
(2) Appliance connections. All gas burning appliances shall be connected to the fuel piping. Materials as provided in § 3280.705(b) or listed appliance connectors shall be used. Listed appliance connectors when used shall not run through walls, floors, ceilings or partitions, except for cabinetry, and shall be 3 feet or less in length or 6 feet or less for cooking appliances. Connectors of aluminum shall not be used outdoors. A manufactured home containing a combination LP-natural-gas-system may be provided with a gas outlet to supply exterior appliances when installed in accordance with the following:
(i) No portion of the completed installation shall project beyond the wall of the manufactured home.
(ii) The outlet must be provided with an approved quick-disconnect device, which must be designed to provide a positive seal on the supply side of the gas system when the appliance is disconnected. A shutoff valve of the non-displaceable rotor type conforming to ANSI Z21.15-1997, Manually Operated Gas Valves, must be installed immediately upstream of the quick-disconnect device. The complete device must be provided as part of the original installation.
(iii) Protective caps or plugs for the “quick-disconnect” device, when disconnected, shall be permanently attached to the manufactured home adjacent to the device.
(iv) A tag shall be permanently attached to the outside of the exterior wall of the manufactured home as close as possible to the gas supply connection. The tag shall indicate the type of gas and the Btuh capacity of the outlet and shall be legibly inscribed as follows:
THIS OUTLET IS DESIGNED FOR USE WITH GAS PORTABLE APPLIANCES WHOSE TOTAL INPUT DO NOT EXCEED ______ BTUH. REPLACE PROTECTIVE COVERING OVER CONNECTOR WHEN NOT IN USE.
(3) Valves. A shutoff valve must be installed in the fuel piping at each appliance inside the manufactured home structure, upstream of the union or connector in addition to any valve on the appliance and so arranged to be accessible to permit servicing of the appliance and removal of its components. The shutoff valve must be located within 6 feet of any cooking appliance and within 3 feet of any other appliance. A shutoff valve may serve more than one appliance if located as required by this paragraph (3). The shutoff valve must be of the non-displaceable rotor type and conform to ANSI Z21.15-1997, Manually Operated Gas Valves.
(4) Gas piping system openings. All openings in the gas piping system shall be closed gas-tight with threaded pipe plugs or pipe caps.
(5) Electrical ground. Gas piping shall not be used for an electrical ground.
(6) Couplings. Pipe couplings and unions shall be used to join sections of threaded piping. Right and left nipples or couplings shall not be used.
(7) Hangers and supports. All horizontal gas piping must be adequately supported by galvanized or equivalently protected metal straps or hangers at intervals of not more than 4 feet, except where adequate support and protection is provided by structural members. Vertical gas piping in multi-story dwelling units must be supported at intervals of not more than 6 feet. Solid iron-pipe connection(s) must be rigidly anchored to a structural member within 6 inches of the supply connection(s).
(8) Testing for leakage. (i) Before appliances are connected, piping systems must stand a pressure of three ± 0.2 psi gauge for a period of not less than ten minutes without showing any drop in pressure. Pressure must be measured with a mercury manometer or slope gauge calibrated so as to be read in increments of not greater than one-tenth pound, or an equivalent device. The source of normal operating pressure must be isolated before the pressure tests are made. Before a test is begun, the temperature of the ambient air and of the piping must be approximately the same, and constant air temperature must be maintained throughout the test.
(ii) After appliances are connected, the piping system shall be pressurized to not less than 10 inches nor more than 14 inches water column and the appliance connections tested for leakage with soapy water or bubble solution.
(iii) Where gas piping between transportable sections must be made on site, the installation instructions must contain provisions for onsite testing for leakage consistent with the provisions in paragraph (l)(8)(i) of this section.
§ 3280.706   Oil piping systems.
(a) General. The requirements of this section shall govern the installation of all liquid fuel piping attached to any manufactured home. None of the requirements listed in this section shall apply to the piping in the appliance(s).
(b) Materials. All materials used for the installation extension, alteration, or repair, of any oil piping systems shall be new and free from defects or internal obstructions. The system shall be made of materials having a melting point of not less than 1,450 F, except as provided in § 280.706(d) and (e). They shall consist of one or more of the materials described in § 3280.706(b) (1) through (4).
(1) Steel or wrought-iron pipe shall comply with ANSI B 36.10-1979, Welded and Seamless Wrought Steel Pipe. Threaded copper or brass pipe in iron pipe sizes may be used.
(2) Fittings for oil piping shall be wrought-iron, malleable iron, steel, or brass (containing not more than 75 percent copper).
(3) Copper tubing must be annealed type, Grade K or L conforming to the Standard Specification for Seamless Copper Water Tube, ASTM B88-93, or shall comply with ASTM B280-1995, Standard Specification for Seamless Copper Tube for Air Conditioning and Refrigeration Field Service.
(4) Steel tubing shall have a minimum wall thickness of 0.032 inch for diameters up to 1/2 inch and 0.049 inch for diameters 1/2 inch and larger. Steel tubing shall be constructed in accordance with the Specification for Electric-Resistance-Welded Coiled Steel Tubing for Gas and Field Oil Lines, ASTM, A539-90a, and shall be externally corrosion protected.
(c) Size of oil piping. The minimum size of all fuel oil tank piping connecting outside tanks to the appliance shall be no smaller than 3/8 inch OD copper tubing or 1/4 inch IPS. If No. 1 fuel oil is used with a listed automatic pump (fuel lifter), copper tubing shall be sized as specified by the pump manufacturer.
(d) Joints for oil piping. All pipe joints in the piping system, unless welded or brazed, shall be threaded joints which comply with ANSI/ASME B1.20.1-1983, Pipe Threads, General Purpose (Inch). The material used for brazing pipe connections shall have a melting temperature in excess of 1,000 F.
(e) Joints for tubing. Joints in tubing shall be made with either a single or double flare of the proper degree, as recommended by the tubing manufacturer, by means of listed tubing fittings, or brazed with materials having a melting point in excess of 1,000 F.
(f) Pipe joint compound. Threaded joints shall be made up tight with listed pipe joint compound which shall be applied to the male threads only.
(g) Couplings. Pipe couplings and unions shall be used to join sections of threaded pipe. Right and left nipples or couplings shall not be used.
(h) Grade of piping. Fuel oil piping installed in conjunction with gravity feed systems to oil heating equipment shall slope in a gradual rise upward from a central location to both the oil tank and the appliance in order to eliminate air locks.
(i) Strap hangers. All oil piping shall be adequately supported by galvanized or equivalently protected metal straps or hangers at intervals of not more than 4 feet, except where adequate support and protection is provided by structural members. Solid-iron-pipe oil supply connection(s) shall be rigidly anchored to a structural member within 6 inches of the supply connection(s).
(j) Testing Tag. A tag must be affixed to each oil-fired appliance stating: “Before setting the system in operation, tank installations and piping must be checked for oil leaks with fuel oil of the same grade that will be burned in the appliance. No other material may be used for testing fuel oil tanks and piping. Tanks must be filled to maximum capacity for the final check for oil leakage.”
§ 3280.707   Heat producing appliances.
(a) Heat-producing appliances and vents, roof jacks and chimneys necessary for their installation in manufactured homes shall be listed or certified by a nationally recognized testing agency for use in manufactured homes.
(1) A manufactured home shall be provided with a comfort heating system.
(i) When a manufactured home is manufactured to contain a heating appliance, the heating appliance shall be installed by the manufacturer of the manufactured home in compliance with applicable sections of this subpart.
(ii) When a manufactured home is manufactured for field application of an external heating or combination heating/cooling appliance, preparation of the manufactured home for this external application shall comply with the applicable sections of this part.
(2) Each gas and oil burning comfort heating appliance must have an Annual Fuel Utilization Efficiency of not less than that specified in 10 CFR part 430, Energy Conservation Program for Consumer Products: Test Procedures for Furnaces/Boilers, Vented Home Heating Equipment and Pool Heaters.
(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. Each automatic storage water heater must comply with the efficiency requirements of 10 CFR part 430, Energy Conservation Program for Consumer Products: Energy Conservation Standards for Water Heaters.
(1) All automatic electric storage water heaters installed in manufactured homes shall have a standby loss not exceeding 43 watts/meter 2 (4 watts/ft 2 ) of tank surface area. The method of test for standby loss shall be as described in section 4.3.1 of Household Automatic Electric Storage Type Water Heaters, ANSI C72.1-1972.
(2) All gas and oil-fired automatic storage water heaters shall have a recovery efficiency, E, and a standby loss, S, as described below. The method of test of E and S shall be as described in section 2.7 of Gas Water heaters, Vol. I, Storage Water Heaters with Input/Ratings of 75,000 BTU per hour or less, ANSI Z21.10.1-1998 with addendums Z21.10.1a-2000, and Z21.10.1b-1992, 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.
(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 control shall be placed a minimum of 3 feet from the vertical edge of the appliance compartment door. It shall not be located on an exterior wall or on a wall separating the appliance compartment from a habitable room.
(f) Oil-fired heating equipment. All oil-fired heating equipment must conform to Liquid Fuel-burning Heating Appliances for Manufactured Homes and Recreational Vehicles, UL 307A-1995, with 1997 revisions, and be installed in accordance with Standard for the Installation of Oil Burning Equipment, NFPA 31-01 (incorporated by reference, see § 3280.4). Regardless of the requirements of the above-referenced standards, or any other standards referenced in this part, the following are not required:
(1) External switches or remote controls which shut off the burner or the flow of oil to the burner, or
(2) An emergency disconnect switch to interrupt electric power to the equipment under conditions of excessive temperature.
§ 3280.708   Exhaust duct system and provisions for the future installation of a clothes dryer.
(a) Clothes dryers. (1) All gas and electric clothes dryers must be exhausted to the outside by a moisture/lint exhaust duct and termination fitting. When the manufacturer supplies the clothes dryer, the exhaust duct and termination fittings must be completely installed by the manufacturer. If the exhaust duct system is subject to damage during transportation, or a field connection between transportable sections is required, complete factory installation of the exhaust duct system is not required when the following apply:
(i) The exhaust duct system is connected to the clothes dryer, and
(ii) A moisture lint exhaust duct system is roughed in and installation instructions are provided in accordance with paragraph (b)(3) or (c) of this section.
(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 manufactured 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.
(5) Moisture-lint exhaust duct and termination fittings shall be installed in accordance with the appliance manufacturer's printed instructions.
(b) Provisions for future installation of a gas clothes dryer. A manufactured 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 duct system consisting of a complete access space (hole) through the wall or floor cavity with a cap or cover on the interior and exterior of the cavity secured in such a manner that they can be removed by a common household tool shall be provided. The cap or cover in place shall limit air infiltration and be designed to resist the entry of water or rodents. The manufacturer is not required to provide the moisture-lint exhaust duct or the termination fitting. The manufacturer shall provide written instructions to the owner on how to complete the exhaust duct installation in accordance with provisions of § 3280.708(a)(1) through (5).
(c) Provisions for future installation of electric clothes dryers. When wiring is installed to supply an electric clothes dryer for future installation by the owner, the manufacturer shall:
(1) Provide a roughed in moisture-lint exhaust duct system consisting of a complete access space (hole) through the wall or floor cavity with a cap or cover on the interior and exterior of the cavity which are secured in such a manner that they can be removed by the use of common household tools. The cap or cover in place shall limit air filtration and be designed to resist the entry of water or rodents into the home. The manufacturer is not required to provide the moisture-lint exhaust duct or the termination fitting;
(2) Install a receptacle for future connection of the dryer;
(3) Provide written instructions on how to complete the exhaust duct installation in accordance with the provisions of paragraphs (a)(1) through (5) of this section.
§ 3280.709   Installation of appliances.
(a) The installation of each appliance must conform to the terms of its listing and the manufacturer's instructions. The manufactured home manufacturer must leave the appliance manufacturer's instructions attached to the appliance. Every appliance must be secured in place to avoid displacement. For the purpose of servicing and replacement, each appliance must be both accessible and removable.
(1) A direct vent space heating appliance is permitted to be shipped loose for on-site installation in a basement provided the following:
(i) The heating appliance is listed for the installation.
(ii) Approved installation instructions are provided that include requirements for completion of all gas and electrical connections and provide for the manufacturer's inspection and/or testing of all connections.
(iii) Approved instructions are provided to assure connection of the vent and combustion air systems in accordance with § 3280.710(b), and to provide for the manufacturer's inspection of the systems for compliance.
(iv) Approved installation and the manufacturer's inspection procedures are provided for the connection of the site-installed heating appliance to the factory-installed circulation air system and return air systems.
(2) The procedures must include revisions to assure compliance of the installed systems with § 3280.715.
(b) Heat-producing 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 surrounding heat producing appliances shall not be less than the clearances specified in the terms of their listings.
(1) Prevention of storage. The area surrounding heat producing appliances installed in areas with interior or exterior access shall be framed-in or guarded with noncombustible material such that the distance from the appliance to the framing or guarding material is not greater than three inches unless the appliance is installed in compliance with paragraph (c)(2), of this section. When clearance required by the listing is greater than three inches, the guard or frame shall not be closer to the appliance than the distance provided in the listing.
(2) Clearance spaces surrounding heat producing appliances are not required to be framed-in or guarded when:
(i) A space is designed specifically for a clothes washer or dryer;
(ii) Dimensions surrounding the appliance do not exceed three inches; or
(iii) The manufacturer affixes either to a side of an alcove or compartment containing the appliance, or to the appliance itself, in a clearly visible location, a 3″ × 5″ adhesive backed plastic laminated label or the equivalent which reads as follows:
This compartment is not to be used as a storage area. Storage of combustible materials or containers on or near any appliance in this compartment may create a fire hazard. Do not store such materials or containers in this compartment.
(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 manufactured 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) appliances, 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 manufactured home. There shall not be any door, removable access panel, or other opening into the enclosure from the inside of the manufactured 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 circulating air.
(1) The air circulating fan of 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 § 3280.709(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 specifically 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 manufactured home manufacturer has complied with certification required in § 3280.511.
(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 field installed, the home manufacturer shall make provision for proper location of the connections to the supply and return air systems. The manufacturer is not required to provide said appliance(s). The preparation by the manufacturer for connection to the home's supply and return air system shall include all fittings and connection ducts to the main duct and return air system such that the installer is only required to provide:
(i) The appliance;
(ii) Any appliance connections to the home; and
(iii) The connecting duct between the external appliance and the fitting installed on the home by the manufacturer. The above connection preparations by the manufacturer do not apply to supply or return air systems designed only to accept external cooling (i.e., self contained air conditioning systems, etc.)
(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 manufactured home supply and return air system during the operation of the heating appliance installed in the manufactured 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 § 3280.204).
(g) Solid fuel-burning factory-built fireplaces and fireplace stoves listed for use in manufactured homes may be installed in manufactured 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 manufactured 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 part 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 manufactured home.
(iv) The fireplace or fireplace stove shall not be installed in a sleeping room.
(v) Hearth extension shall be of noncombustible material not less than 3/8 -inch thick. The hearth shall extend at least 16 inches in front or 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 manufactured 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 manufactured home.
(h) A corrosion resistant water drip collection and drain pan must be installed under each water heater that will allow water leaking from the water heater to drain to the exterior of the manufactured home, or to a drain.
§ 3280.710   Venting, ventilation and combustion air.
(a) The venting as required by § 3280.707(b) shall be accomplished by one or more of the methods given in (a)(1) and (2) of this section:
(1) An integral vent 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 listing and the appliance manufacturer's instructions.
(b) Venting and combustion air systems shall be installed in accordance with the following:
(1) Components shall be securely assembled and properly aligned at the factory in accordance with the appliance manufacturer's instructions except vertical or horizontal sections of a fuel fired heating appliance venting system that extend beyond the roof line or outside the wall line may be installed at the site. Sectional venting systems shall be listed for such applications and installed in accordance with the terms of their listings and manufacturers' instructions. In cases where sections of the venting system are removed for transportation, a label shall be permanently attached to the appliance indicating the following:
Sections of the venting system have not been installed. Warning-do not operate the appliance until all sections have been assembled and installed in accordance with the 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 manufactured home.
(d) Venting systems of fuel-burning appliances must terminate at least three feet above any motor-driven air intake discharging into habitable rooms when located within ten feet of the air intake.
(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 manufactured 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 within 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.
§ 3280.711   Instructions.
Operating instructions must be provided with each appliance. The operating and installation instructions for each appliance must be provided with the homeowner's manual.
§ 3280.712   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 manufactured home.
(b) Each fuel-burning appliance shall bear permanent marking designating the type(s) of fuel for which it is listed.
§ 3280.713   Accessibility.
Every appliance shall be accessible for inspection, service, repair, and replacement without removing permanent construction. For those purposes, inlet piping supplying the appliance shall not be considered permanent construction. Sufficient room shall be available to enable the operator to observe the burner, control, and ignition means while starting the appliance.
§ 3280.714   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 ARI Standard 210/240-89 Unitary Air Conditioning and Air Source Unitary Heat Pump Equipment (incorporated by reference, see § 3280.4) and certified by ARI or other nationally recognized testing agency capable of providing follow-up service.
(i) Electric motor-driven unitary air-cooled air conditioners and heat pumps in the cooling mode with rated capacity less than 65,000 BTU/hour (19,045 watts), when rated at ARI standard rating conditions in ARI Standard 210/240-89, Unitary Air-Conditioning and Air-Source Heat Pump Equipment, must have seasonal energy efficiency (SEER) values not less than as specified in 10 CFR Part 430, Energy Conservation Program for Consumer Products: Central Air Conditioners and Heat Pumps Energy Conservation Standards.
(ii) Heat pumps must be certified to comply with all requirements of the ARI Standard 210/240-89, Unitary Air Conditioning and Air-Source Heat Pump Equipment. Electric motor-driven vapor compression heat pumps with supplemental electrical resistance heat must be sized to provide by compression at least 60 percent of the calculated annual heating requirements for the manufactured home being served. A control must be provided and set to prevent operation of supplemental electrical resistance heat at outdoor temperatures above 40 °F (4 °C), except for defrost conditions. Electric motor-driven vapor compression heat pumps with supplemental electric resistance heat conforming to ARI Standard 210/240-89, Unitary Air-Conditioning and Air-Source Heat Pump Equipment, must have Heating Season Performance Factor (HSPF) efficiencies not less than as specified in the 10 CFR Part 430, Energy Conservation Program for Consumer Products: Central Air Conditioners and Heat Pumps Energy Conservation Standards.
(iii) Electric motor-driven vapor compression heat pumps with supplemental electric resistance heat conforming to ARI Standard 210/240-89 Unitary Air-Conditioning and Air-Source Heat Pump Equipment shall show coefficient of performance ratios not less than shown below:
COP
(2) Gas fired absorption air conditioners must be listed or certified in accordance with ANSI Z21.40.1-1996, Gas Fired, Heat Activated, Air Conditioning and Heat Pump Appliances (incorporated by reference, see § 3280.4), and certified by a nationally recognized testing agency capable of providing follow-up service.
(3) Direct refrigerating systems serving any air conditioning or comfort-cooling system installed in a manufactured 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 Chemicals.”
(4) When a cooling or heat pump coil and air conditioner blower are installed with a furnace or heating appliance, they shall be tested and listed in combination for heating and safety performance by a nationally recognized testing agency.
(5) Cooling or heat pump indoor coils and outdoor sections shall be certified, listed and rated in combination for capacity and efficiency by a nationally recognized testing agency(ies). Rating procedures shall be based on U.S. Department of Energy test procedures.
(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 instructions. The installer shall include the manufacturer's installation instructions in the manufactured 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.
§ 3280.715   Circulating air systems.
(a) Supply system. (1) Supply air ducts, fittings, and any dampers contained therein must be made of galvanized steel, tin-plated steel, or aluminum, or must be listed as Class 0 or Class 1 air ducts and air connectors in accordance with UL 181-2003, Factory-Made Air Ducts and Air Connectors (incorporated by reference, see § 3280.4). Class 1 air ducts and air connectors must be located at least 3 feet from the furnace bonnet or plenum. Air connectors must not be used for exterior manufactured home duct connection. A duct system integral with the structure must be of durable construction that can be demonstrated to be equally resistant to fire and deterioration as required by this section. Furnace supply plenums must be constructed of metal that extends a minimum of 3 feet from the heat exchanger measured along the centerline of airflow. Ducts constructed from sheet metal must be in accordance with the following table:
Minimum Metal Thickness for Ducts 1
1 When “nominal” thicknesses 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 labeled forced-air furnace is installed and operated continuously at its normal heating air circulating rate in the manufactured 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 duct, 2 1/2 inches.
(3) Sizing of ducts. (i) The manufactured 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 § 3280.511).
(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 manufactured 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 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, with its outlets sealed and the furnace air circulator operating at high speed. For the purpose of this paragraph and § 3280.715(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 manufactured home connections. (i) An expandable or multiple manufactured 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 manufactured home is fully expanded or coupled, the resulting duct joint will conform to the requirements of this part.
(ii) The manufacturer must provide installation instructions for supporting, mechanically fastening, sealing, and insulating each crossover duct. The instructions must indicate that no portion of the crossover duct is to be in contact with the ground, and must describe the means to support the duct without compressing the insulation and restricting airflow.
(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 manufactured home insulation having a minimum effective value of R-4.0 for floors or R-6.0 for ceilings.
(7) Unless installed in a basement, supply and return ducts, fittings, and crossover duct plenums exposed directly to outside air, such as those under-chassis crossover ducts or ducts connecting external heating, cooling, or combination heating/cooling appliances, must be insulated with material having a minimum thermal resistance of R-8 in all Thermal Zones. All such insulating materials must have a continuous vapor barrier retarder having a perm rating of not more than 1 perm. Where ducts are exposed underneath the manufactured home, they must comply with paragraph (a)(5)(ii) of this section, and shall be listed for exterior use.
(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 directly 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 § 3280.715(a)(1) or shall be listed Class 0 or Class 1 air ducts.
(ii) Return ducts, except as required by paragraph (a) of this section, shall be constructed of one-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 § 3280.715(a)(1).
(iii) The interior of combustible 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 manufactured 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 metal in accordance with § 3280.715(a)(1) 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 ultraviolet 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 separating partitions to allow circulated air to return to the furnace. Such openings may be grilled or louvered. The net free area of each opening shall be not less than 1 square inch for every 5 square feet of total living area closed off from the furnace 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 not more than 2 1/2 inches, as measured from the top surface of the floor decking to the bottom of the door 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 sheet metal and factory-made flexible ducts, including trunks, branches, risers, crossover ducts, and crossover duct plenums, shall be mechanically secured and made substantially airtight. Slip joints in sheet metal ducts shall have a lap of at least one inch and shall be mechanically fastened. Tapes or caulking compounds shall be permitted to be used for sealing mechanically secure joints. Sealants and tapes shall be applied only to surfaces that are dry and dust-, dirt-, oil-, and grease-free. Tapes and mastic closure systems for use with factory-made rigid fiberglass air ducts and air connectors shall be listed in accordance with UL Standard 181A-1994, with 1998 revisions. Tapes and mastic closure systems used with factory-made flexible air ducts and air connectors shall be listed in accordance with UL Standard 181B-1995, with 1998 revisions.
(d) Supports and protection. Ducts must be securely supported. Nails or other fasteners must not be driven or penetrate through duct walls. Where vertical ducts are installed within closets or rooms, they must be enclosed with materials equivalent to those used in the closet or room construction.
(e) Registers and grilles. Fittings connecting the registers and grilles to the duct system must be constructed of metal or material that complies with the requirements of Class 1 or 2 ducts under UL 181-1996 with 1998 revisions, Factory Made Air Ducts and Connectors. Air supply terminal devices (registers) when installed in kitchen, bedrooms, and bathrooms must be equipped with adjustable closeable dampers. Registers or grilles must be constructed of metal or conform with the following:
(1) Be made of a material classified 94V-0 or 94V-1, when tested as described in UL 94-1996, with 2001 revisions, Test for Flammability of Plastic Materials for Parts in Devices and Appliances, Fifth Edition; and
(2) Floor registers 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.
§ 3280.801   Scope.
(a) Subpart I of this part and Part II of Article 550 of the National Electrical Code (NFPA No. 70-2005) cover the electrical conductors and equipment installed within or on manufactured homes and the conductors that connect manufactured homes to a supply of electricity.
(b) In addition to the requirements of this part and Part II of Article 550 of the National Electrical Code (NFPA No. 70-2005), the applicable portions of other Articles of the National Electrical Code must be followed for electrical installations in manufactured homes. The use of arc-fault breakers under Articles 210.12(A) and (B), 440.65, and 550.25(A) and (B) of the National Electrical Code, NFPA No. 70-2005 is not required. However, if arc-fault breakers are provided, such use must be in accordance with the National Electrical Code, NFPA No. 70-2005. Wherever the requirements of this standard differ from the National Electrical Code, these standards apply.
(c) The provisions of this standard apply to manufactured homes intended for connection to a wiring system nominally rated 120/240 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, aluminum alloy conductors, and aluminum core conductors such as copper clad aluminum; are not acceptable for use in branch circuit wiring in manufactured homes.
§ 3280.802   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 manufactured home structure or finish, or not permanently closed-in by the structure or finish of the manufactured 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 which is fastened or otherwise secured at a specific location.
(iii) 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) Attached accessory building or structure means any awning, cabana, deck, ramada, storage cabinet, carport, windbreak, garage, or porch for which the attachment of such is designed by the home manufacturer to be structurally supported by the manufactured home.
(5) 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.
(6) 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.
(7) 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.
(8) 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.
(9) 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.
(10) Concealed means rendered inaccessible by the structure or finish of the manufactured home. Wires in concealed raceways are considered concealed, even though they may become accessible by withdrawing them. (See accessible (As applied to wiring methods) )
(11) 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.
(12) Dead front (as applied to switches, circuit-breakers, switchboards, and distribution panelboard) means so designed, constructed, and installed that no current-carrying parts are normally exposed on the front.
(13) Demand factor means the 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.
(14) Device means a unit of an electrical system that is intended to carry but not utilize electrical energy.
(15) 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.
(16) 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.
(17) Enclosed means surrounded by a case that will prevent a person from accidentally contacting live parts.
(18) 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.
(19) 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) )
(20) Externally operable means capable of being operated without exposing the operator to contact with live parts.
(21) 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 manufactured home use, designed for the purpose of delivering energy from the source of electrical supply to the distribution panelboard within the manufactured home.
(22) 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.
(23) 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.
(24) Grounded means connected to earth or to some conducting body that serves in place of the earth.
(25) Grounded conductor means a system or circuit conductor that is intentionally grounded.
(26) Grounding conductor means a conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes.
(27) 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.
(28) Isolated means not readily accessible to persons unless special means for access are used.
(29) Laundry area means an area containing or designed to contain either a laundry tray, clothes washer and/or clothes dryer.
(30) Lighting outlet means an outlet intended for the direct connection of a lampholder, a lighting fixture, or a pendant cord terminating in a lampholder.
(31) Manufactured home accessory building or structure means any awning, cabana, ramada, storage cabinet, carport, fence, windbreak or porch established for the use of the occupant of the manufactured home upon a manufactured home lot.
(32) Manufactured home service equipment means the equipment containing the disconnecting means, overcurrent protective devices, and receptacles or other means for connecting a manufactured home feeder assembly.
(33) Outlet means a point on the wiring system at which current is taken to supply utilization equipment.
(34) Panelboard means a single panel or group of panel units designed for 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.
(35) 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.
(36) Raintight means so constructed or protected that exposure to a beating rain will not result in the entrance of water.
(37) 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, chairs, etc. (See Accessible. )
(38) Receptacle means a contact device installed at the outlet for the connection of an attachment plug. A single receptacle is a single contact device with no other contact device on the same yoke. A multiple receptacle is a device with two or more contact devices on the same yoke.
(39) Receptacle outlet means an outlet where one or more receptacles are installed.
(40) Utilization equipment means equipment that utilizes electric energy for electronic, electromechanical, chemical, heating, lighting, or similar purposes.
(41) 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.
(42) 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.
(b) [Reserved]
§ 3280.803   Power supply.
(a) The power supply to the manufactured home shall be a feeder assembly consisting of not more than one listed 50 ampere manufactured home power-supply cords, or a permanently installed circuit. A manufactured 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 manufactured home power-supply cord rated 40 amperes.
(b) If the manufactured 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 manufactured home.
(d) A suitable clamp or the equivalent must 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 must be a 3-pole, 4-wire, grounding type, rated 50 amperes, 125/250 volts, intended for use with the 50-ampere, 125/250-volt receptacle configuration, as shown below. The cap must be listed, by itself or as part of a power-supply cord assembly, for the purpose, and must be molded to or installed on the flexible cord so that it is secured tightly to the cord at the point where the cord enters the attachment plug cap. If a right-angle cap is used, the configuration must 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 manufactured home shall not be less than 20 feet.
(h) The power supply cord shall bear the following marking: “For use with manufactured homes—40 amperes” or “For use with manufactured homes—50 amperes.”
(i) Where the cord passes through walls or floors, it must be protected by means of conduits and bushings or the equivalent. The cord is permitted to be installed within the manufactured home walls, provided that a continuous raceway having a maximum size of 1 1/4 inch is installed from the branch-circuit panelboard to the underside of the manufactured home floor.
(j) 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 manufactured home is in transit.
(k) 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. 70-2005, containing four continuous insulated, color-coded, feeder conductors, one of which shall be an equipment grounding conductor; or
(2) A listed metal raceway or listed rigid nonmetallic conduit from the disconnecting means in the manufactured home to the underside of the manufactured home, with provisions for the attachment of a suitable junction box or fitting to the raceway on the underside of the manufactured home. The manufacturer must provide written installation instructions stating the proper feeder conductor sizes for the raceway and the size of the junction box to be used; or
(3) Service equipment installed in or on the manufactured home, provided that all of the following conditions are met:
(i) In its written installation instructions, the manufacturer must include information indicating that the home must be secured in place by an anchoring system or installed on and secured to a permanent foundation;
(ii) The installation of the service equipment complies with Article 230 of the National Electrical Code, NFPA 70-2005 (incorporated by reference, see § 3280.4). Exterior service equipment or the enclosure in which it is to be installed must be weatherproof, and conductors must be suitable for use in wet locations;
(iii) Means are provided for the connection of the grounding electrode conductor to the service equipment and routing it to the conductor outside the structure;
(iv) Bonding and grounding of the service must be in accordance with Article 250, NFPA 70-2005, National Electrical Code (incorporated by reference, see § 3280.4);
(v) The manufacturer must include in its installation instructions one method of grounding the service equipment at the installation site. The instructions must clearly state that other methods of grounding are found in Article 250 of NFPA 70-2005, National Electrical Code;
(vi) The minimum size grounding electrode conductor must be specified in the instructions; and
(vi) A red warning label must be mounted on or adjacent to the service equipment. The label must state the following: WARNING—DO NOT PROVIDE ELECTRICAL POWER UNTIL THE GROUNDING ELECTRODE(S) IS INSTALLED AND CONNECTED (SEE INSTALLATION INSTRUCTIONS).
§ 3280.804   Disconnecting means and branch-circuit protective equipment.
(a) The branch-circuit equipment is permitted to be combined with the disconnecting means as a single assembly. Such a combination is permitted to be designated as a distribution panelboard. If a fused distribution panelboard is used, the maximum fuse size for the mains shall be plainly marked, with the lettering at least 1/4-inch high and visible when fuses are changed. See Article 110-22 of NFPA 70-2005, National Electrical Code (incorporated by reference, see § 3280.4), concerning the identification of each disconnecting means and each service, feeder, or branch circuit at the point where it originated, and the type of 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 must be provided in each manufactured home, consisting of a circuit breaker, or a switch and fuses and its accessories, installed in a readily accessible location near the point of entrance of the supply cord or conductors into the manufactured home. The main circuit breakers or fuses must be plainly marked “Main.” This equipment must 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 must be insulated in accordance with § 3280.809(b).
(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 manufactured home.
(e) A distribution panelboard employing a main circuit breaker must be rated not less than 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 must be rated not less than 60 amperes and must employ a single, 2-pole fuseholder rated not less than 60-amperes with 40- or 50-ampere main fuses for 40- or 50-ampere supply cords, respectively. The outside of the distribution panelboard must be plainly marked with the fuse size.
(f) The distribution panelboard must be located in an accessible location, and must not be located in a bathroom or a clothes closet. A clear working space at least 30 inches wide and 30 inches in front of the distribution panelboard must be provided. This space must extend from the floor to the top of the distribution panelboard. Where used as switches, circuit breakers must be installed so that the center of the grip of the operating handle of the circuit breaker, when in its highest position, will not be more than 6 feet, 7 inches above the floor.
(g) Branch-circuit distribution equipment shall be installed in each manufactured 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 13.3 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 240 circuits shall be protected by 2-pole common or companion trip, or handle-tied paired circuit breakers.
(j) A 3 inch by 1-3/4 inch minimum size tag made of etched, metal-stamped or embossed brass, stainless steel, anodized or alclad aluminum not less than 0.020 inch thick, or other approval material (e.g., 0.005 inch plastic laminates) shall be permanently affixed on the outside adjacent to the feeder assembly entrance and shall read: This connection for 120/240 Volt, 3-Pole, 4-Wire, 60 Hertz, ________ Ampere Supply. The correct ampere rating shall be marked on the blank space.
(k) When a home is provided with installed service equipment, a single disconnecting means for disconnecting the branch circuit conductors from the service entrance conductors must be provided in accordance with Article 230, Part VI of the National Electrical Code, NFPA No. 70-2005. The disconnecting means shall be listed for use as service equipment. The disconnecting means may be combined with the disconnect required by § 3280.804(c). The disconnecting means shall be rated not more than the ampere supply or service capacity indicated on the tag required by paragraph (l) of this section.
(l) When a home is provided with installed service equipment, the electrical nameplate required by § 3280.804(j) shall read: “This connection for 120/240 volt, 3 pole, 3 wire, 60 Hertz, ________ Ampere Supply.” The correct ampere rating shall be marked in the blank space.
§ 3280.805   Branch circuits required.
(a) The number of branch circuits required shall be determined in accordance with the following:
(1) Lighting, based on 3 volt-amperes per square foot times outside dimensions of the manufactured home (coupler excluded) divided by 120 volts times amperes to determine number of 15 or 20 ampere lighting area circuits. e.g. [3 × length × width—[120 × (15 or 20)] = number of 15 or 20 ampere circuits. Lighting circuits are permitted to serve built-in gas ovens with electric service for lights, clocks, or timers, or for listed cord-connected garbage disposal units.
(2) Small Appliances. For the small appliance load in kitchens, pantries, dining rooms, and breakfast rooms of manufactured homes, two or more 20-ampere appliance branch circuits, in addition to the branch circuit specified in paragraph (a)(1) of this section, must be provided for all receptacle outlets in these rooms, and such circuits must have no other outlets. Countertop receptacle outlets installed in the kitchen must be supplied by not less than two small appliance branch circuits. One or more of the small appliance branch circuits may also supply other receptacle outlets in the kitchen, pantry, dining room, and breakfast room. Receptacles installed solely for the electrical supply to an electric clock and receptacles installed to provide power for supplemental equipment and lighting on gas-fired ranges, ovens, or counter-mounted cooking units are not subject to the requirements of this paragraph (a)(2).
(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) The ampere rating of fixed appliances must not exceed 50 percent of the circuit rating if lighting outlets are on the same circuit (receptacles in the kitchen, dining area, and laundry are not considered to be lighting outlets);
(ii) For fixed appliances on a circuit without lighting outlets, the sum of rated amperes shall not exceed the branch-circuit rating. Motor loads or other continuous duty loads shall not exceed 80 percent of the branch circuit rating.
(iii) The rating of a single cord and plug connected appliances on a circuit having no other outlets, shall not exceed 80 percent of the circuit rating.
(iv) The rating of the range branch circuit is based on the range demand as specified for ranges in § 3280.811(a)(5). For central air conditioning, see Article 440 of the National Electrical Code, NFPA No. 70-2005.
(v) Where a laundry area is provided, a 20 ampere branch circuit shall be provided to supply laundry receptacle outlets. This circuit shall have no other outlets. See § 3280.806(a)(7).
(vi) Bathroom receptacle outlets must be supplied by at least one 20-ampere branch circuit. Such circuits must have no other outlets, except that it is permissible to place the receptacle outlet for a heat tape or pipe heating cable required by § 3280.806(d)(10) on a bathroom circuit. (See § 3280.806(b).)
(b) [Reserved]
§ 3280.806   Receptacle outlets.
(a) All receptacle outlets shall be:
(1) Of grounding type;
(2) Installed according to Article 406.3 of the National Electrical Code, NFPA No. 70-2005.
(3) Except when supplying specific appliances, be parallel-blade, 15-ampere, 125-volt, either single or duplex.
(b) All 125-volt, single-phase, 15- and 20-ampere receptacle outlets installed outdoors, or in compartments accessible from outside the manufactured home, and in bathrooms, including receptacles in light fixtures, must have ground-fault circuit-interrupter protection for personnel. Ground-fault circuit-interrupter protection for personnel must be provided for receptacles serving countertops in kitchens and receptacle outlets located within 6 feet of a wet bar sink, except for receptacles installed for appliances in dedicated spaces, such as dishwashers, disposals, refrigerators, freezers, and laundry equipment.
(c) There shall be an outlet of the grounding type for each cord-connected fixed appliance installed.
(d) Receptacle outlets required. Except in the bath, closet, and hall areas, receptacle outlets must be installed at wall spaces 2 feet or more wide, so that no point along the floor line is more than 6 feet, measured horizontally, from an outlet in that space. Receptacle outlets in floors shall not be counted as part of the required number of receptacle outlets, unless located within 18 inches of the wall. In addition, a receptacle outlet must be installed in the following locations:
(1) Over or adjacent to counter tops in the kitchen (at least one on each side of the sink if counter tops are on each side and 12 inches or over in width).
(2) Adjacent to the refrigerator and free-standing gas-range space. A duplex receptacle may serve as the outlet for a countertop and a refrigerator.
(3) At counter top spaces for built-in vanities.
(4) At counter top spaces under wall-mounted cabinets.
(5) In the wall, at the nearest point where a bar type counter attaches to the wall.
(6) In the wall at the nearest point where a fixed room divider attaches to the wall.
(7) In laundry areas within 6 feet of the intended location of the appliance(s).
(8) At least one receptacle outlet shall be installed outdoors.
(9) At least one wall receptacle outlet shall be installed in bathrooms within 36 inches (914 mm) of the outside edge of each basin. The receptacle outlet must be located on a wall that is adjacent to the basin location. This receptacle is in addition to any receptacle that is part of a lighting fixture or appliance. The receptacle must not be enclosed within a bathroom cabinet or vanity.
(10) On the underside of the home for the connection of pipe heating cable(s) or heat tape(s), and the outlet must:
(i) Be located within 2 feet of the cold water inlet;
(ii) Be connected to an interior branch circuit, other than a small appliance branch circuit;
(iii) Be located on a circuit where all of the outlets are on the load side of the ground-fault circuit-interrupter protection for personnel; and
(iv) Not be considered as the receptacle outlet required by paragraph (8) of this section.
(11) Receptacle outlets are not required in the following locations:
(i) Wall space occupied by built-in kitchen or wardrobe cabinets,
(ii) Wall space behind doors which may be opened fully against a wall surface,
(iii) Room dividers of the lattice type, less than 8 feet long, not solid within 6 inches of the floor,
(iv) Wall space afforded by bar type counters.
(e) Receptacle outlets shall not be installed in or within reach (30 inches) of a shower or bathtub space.
(f) Receptacle outlets shall not be installed above electric baseboard heaters.
(g) Receptacles must not be in a face-up position in any countertop.
§ 3280.807   Fixtures and appliances.
(a) Electrical materials, devices, appliances, fittings, and other equipment installed, intended for use in, or attached to the manufactured home shall be approved for the application and shall be connected in an approved manner when in service. Facilities shall be provided to securely fasten appliances when the manufactured home is in transit. (See § 3280.809.)
(b) Specifically listed pendant-type fixtures or pendant cords shall be permitted in manufactured homes.
(c) Where a lighting fixture is installed over a bathtub or in a shower stall, it must be listed for wet locations. [See also Article 410.4(D) of the National Electrical Code NFPA No. 70-2005.]
(d) The switch for shower lighting fixtures and exhaust fans located over a tub or in a shower stall shall be located outside the tub shower space. (See § 3280.806(e).)
(e) Any combustible wall or ceiling finish exposed between the edge of a fixture canopy, or pan and an outlet box shall be covered with non-combustible or limited combustible material.
(f) Every appliance shall be accessible for inspection, service, repair, or replacement without removal of permanent construction.
(g) In bathrooms, ceiling-mounted lighting fixtures and wall-mounted lighting fixtures must not be controlled by the same switch.
§ 3280.808   Wiring methods and materials.
(a) Except as specifically permitted by this part, the wiring methods and materials specified in the National Electrical Code, NFPA No. 70-2005, must be used in manufactured homes.
(b) Nonmetallic outlet boxes shall be acceptable only with nonmetallic cable.
(c) Nonmetallic cable located 15 inches or less above the floor, if exposed, shall be protected from physical damage by covering boards, guard strips, or conduit. Cable likely to be damaged by stowage shall be so protected in all cases.
(d) Nonmetallic sheathed cable shall be secured by staples, straps, or similar fittings so designed and installed as not to injure any cable. Cable shall be secured in place at intervals not exceeding 4 1/2 feet and within 12 inches from every cabinet, box or fitting.
(e) Metal-clad and nonmetallic cables shall be permitted to pass through the centers of the wide side of 2-inch by 4-inch studs. However, they shall be protected where they pass through 2-inch by 2-inch studs or at other studs or frames where the cable or armor would be less than 1 1/2 inches from the inside or outside surface of the studs when the wall covering materials are in contact with the studs. Steel plates on each side of the cable, or a tube, with not less than No. 16 MSG wall thickness shall be required to protect the cable. These plates or tubes shall be securely held in place.
(f) Where metal faceplates are used, they must be effectively grounded.
(g) If the range, clothes dryer, or similar appliance is connected by metalclad cable or flexible conduit, a length of not less than three feet of free cable or conduit shall be provided to permit moving the appliance. Type NM or Type SE cable shall not be used to connect a range or a dryer. This shall not prohibit the use of Type NM or Type SE cable between the branch circuit overcurrent protective device and a junction box or range or dryer receptacle.
(h) Where rigid metal conduit or intermediate metal conduit is terminated at an enclosure with a locknut and bushing connection, two locknuts must be provided, one inside and one outside of the enclosure. Rigid nonmetallic conduit or electrical nonmetallic tubing is permitted. All cut ends of conduit and tubing must be reamed or otherwise finished to remove rough edges.
(i) Switches must be rated as follows:
(1) For lighting circuits, switches must be rated not less than 10 amperes, 120 to 125 volts, and in no case less than the connected load.
(2) For motors or other loads, switches shall have ampere or horsepower ratings, or both, adequate for loads controlled. (An “AC general-use” snap switch shall be permitted to control a motor 2 horsepower or less with full-load current not over 80 percent of the switch ampere rating).
(j) At least 4 inches of free conductor shall be left at each outlet box except where conductors are intended to loop without joints.
(k) When outdoor or under-chassis line-voltage (120 volts, nominal or higher) wiring is exposed to moisture or physical damage, it must be protected by rigid metal conduit or intermediate metal conduit. The conductors must be suitable for wet locations. Electrical metallic tubing or rigid nonmetallic conduit is permitted to be used when closely routed against frames and equipment enclosures.
(l) Outlet boxes of dimensions less than those required in Table 314.16(A) of the National Electrical Code, NFPA No. 70-2005, are permitted provided the box has been tested and approved for that purpose.
(m) Boxes, fittings, and cabinets shall be securely fastened in place, and shall be supported from a structural member of the home, either directly or by using a substantial brace. Snap-in type boxes provided with special wall or ceiling brackets that securely fasten boxes in walls or ceilings shall be permitted.
(n) Outlet boxes must fit closely to openings in combustible walls and ceilings and must be flush with the finish surface or project therefrom. In walls and ceilings of noncombustible material, outlet boxes and fittings must be installed so that the front edge of the box or fitting will not be set back from the finished surface more than 1/4 inch. Plaster, drywall, or plasterboard surfaces that are broken or incomplete must be repaired so that there will be no gaps or open spaces greater than 1/8 inch at the edge of the box or fitting.
(o) Appliances having branch-circuit terminal connections which operate at temperatures higher than 60 °C (140 °F) shall have circuit conductors as described in paragraphs (p) (1) and (2) of this section:
(1) Branch-circuit conductors having an insulation suitable for the temperature encountered shall be permitted to run directly to the appliance.
(2) Conductors having an insulation suitable for the temperature encountered may be run from the appliance terminal connections to a readily accessible outlet box placed at least one foot from the appliance. If provided, these conductors must be in a suitable raceway or Type AC or MC cable, of at least 18 inches but not more than 6 feet in length.
(p) A substantial brace for securing a box, fitting, or cabinet must be as described in the National Electrical Code, NFPA 70-2005, Article 314.23(B), or the brace, including the fastening mechanism to attach the brace to the home structure, must withstand a force of 50 lbs. applied to the brace at the intended point(s) of attachment for the box in a direction perpendicular to the surface on which the box is installed.
(q) Where the sheathing of NM cable has been cut or damaged and visual inspection reveals that the conductor and its insulation has not been damaged, it shall be permitted to repair the cable sheath with electrical tape which provides equivalent protection to the sheath.
§ 3280.809   Grounding.
(a) General. Grounding of both electrical and nonelectrical metal parts in a manufactured home shall be through connection to a grounding bus in the manufactured home distribution panelboard. The grounding bus shall be grounded through the green-colored conductor in the supply cord or the feeder wiring to the service ground in the service-entrance equipment located adjacent to the manufactured home location. Neither the frame of the manufactured home nor the frame of any appliance shall be connected to the neutral conductor in the manufactured home.
(b) Insulated neutral. (1) The grounded circuit conductor (neutral) shall be insulated from the grounding conductors and from equipment enclosures and other grounded parts. The grounded (neutral) circuit terminals in the distribution panelboard and in ranges, clothes dryers, counter-mounted cooking units, and wall-mounted ovens shall be insulated from the equipment enclosure. Bonding screws, straps, or buses in the distribution panelboard or in appliances shall be removed and discarded. However, when service equipment is installed on the manufactured home, the neutral and the ground bus may be connected in the distribution panel.
(2) Connection of ranges and clothes dryers with 120/240 volt, 3-wire ratings shall be made with 4 conductor cord and 3 pole, 4-wire grounding type plugs, or by type AC metal clad conductors enclosed in flexible metal conduit. For 120 volt rated devices a 3-conductor cord and a 2-pole, 3-wire grounding type plug shall be permitted.
(c) Equipment grounding means. (1) The green-colored grounding wire in the supply cord or permanent feeder wiring shall be connected to the grounding bus in the distribution panelboard or disconnecting means.
(2) In the electrical system, all exposed metal parts, enclosures, frames, lamp fixture canopies, etc., shall be effectively bonded to the grounding terminal or enclosure of the distribution panelboard.
(3) Cord-connected appliances, such as washing machines, clothes dryers, refrigerators, and the electrical system of gas ranges, etc., shall be grounded by means of an approved cord with grounding conductor and grounding-type attachment plug.
(d) Bonding of noncurrent-carrying metal parts. (1) All exposed noncurrent-carrying metal parts that may become energized shall be effectively bonded to the grounding terminal or enclosure of the distribution panelboard. A bonding conductor shall be connected between each distribution panelboard and an accessible terminal on the chassis.
(2) Grounding terminals shall be of the solderless type and approved as pressure-terminal connectors recognized for the wire size used. Star washers or other approved paint-penetrating fitting shall be used to bond terminals to chassis or other coated areas. The bonding conductor shall be solid or stranded, insulated or bare and shall be No. 8 copper minimum, or equal. The bonding conductor shall be routed so as not to be exposed to physical damage. Protection can be afforded by the configuration of the chassis.
(3) Metallic gas, water and waste pipes and metallic air-circulating ducts shall be considered bonded if they are connected to the terminal on the chassis (see § 3280.809) by clamps, solderless connectors, or by suitable grounding-type straps.
(4) Any metallic roof and exterior covering shall be considered bonded if (i) the metal panels overlap one another and are securely attached to the wood or metal frame parts by metallic fasteners, and (ii) if the lower panel of the metallic exterior covering is secured by metallic fasteners at a cross member of the chassis by two metal straps per manufactured home unit or section at opposite ends. The bonding strap material shall be a minimum of 4 inches in width of material equivalent to the skin or a material of equal or better electrical conductivity. The straps shall be fastened with paint-penetrating fittings (such as screws and star washers or equivalent).
§ 3280.810   Electrical testing.
(a) Dielectric strength test. The wiring of each manufactured home shall be subjected to a 1-minute, 900 to 1079 volt dielectric strength test (with all switches closed) between live parts and the manufactured home ground, and neutral and the manufactured home ground. Alternatively, the test may be performed at 1080 to 1250 volts for 1 second. This test shall be performed after branch circuits are complete and after fixtures or appliances are installed. Fixtures or appliances which are listed shall not be required to withstand the dielectric strength test.
(b) Additional testing. Each manufactured home must be subjected to the following tests:
(1) An electrical continuity test to assure that metallic parts are effectively bonded;
(2) An operational test of all devices and utilization equipment, except water heaters, electric ranges, electric furnaces, dishwashers, clothes washers/dryers, and portable appliances, to demonstrate they are connected and in working order; and
(3) Electrical polarity checks to determine that connections have been made in accordance with applicable provisions of these standards and Article 550.17 of NFPA 70-2005 (incorporated by reference, see § 3280.4). Visual verification is an acceptable electrical polarity check.
§ 3280.811   Calculations.
(a) The following method shall be employed in computing the supply cord and distribution-panelboard load for each feeder assembly for each manufactured home and shall be based on a 3-wire, 120/240 volt supply with 120 volt loads balanced between the two legs of the 3-wire system. The total load for determining power supply by this method is the summation of:
(1) Lighting and small appliance load as calculated below:
(i) Lighting volt-amperes: Length time width of manufactured home (outside dimensions exclusive of coupler) times 3 volt-amperes per square foot; e.g. Length × width × 3 = lighting volt-amperes.
(ii) Small appliance volt-amperes: Number of circuits time 1,500 volt-amperes for each 20-ampere appliance receptacle circuit (see definition of “Appliance Portable” with Note): e.g. Number of circuits × 1,500 = small appliance volt-amperes.
(iii) Total volts-amperes: Lighting volts-amperes plus small appliance = total volt-amperes.
(iv) First 3,000 total volts-amperes at 100 percent plus remainder at 35 percent = watts to be divided by 240 volts to obtain current (amperes) per leg.
(2) Nameplate amperes for motors and heater loads (exhaust fans, air conditioners, electric, gas, or oil heating). Omit smaller of air conditioning and heating except include blower motor if used as air conditioner evaporator motor. When an air conditioner is not installed and a 40-ampere power supply cord is provided, allow 15 amperes per leg for air conditioning.
(3) 25 percent of current of largest motor in paragraph (a)(2) of this section.
(4) Total of nameplate amperes for: Disposal, dishwasher, water heater, clothes dryer, wall-mounted oven, cooking units. Where number of these appliances exceeds three, use 75 percent of total.
(5) Derive amperes for free-standing range (as distinguished from separate ovens and cooking units) by dividing values below by 240 volts.
(6) If outlets or circuits are provided for other than factory-installed appliances, include the anticipated load. The following example is given to illustrate the application of this Method of Calculation:
Note: Based on the higher current calculated for either leg, use one 50-A supply cord.
(b) The following is an optional method of calculation for lighting and appliance loads for manufactured homes served by single 3-wire 120/240 volt set of feeder conductors with an ampacity of 100 or greater. The total load for determining the feeder ampacity may be computed in accordance with the following table instead of the method previously specified. Feeder conductors whose demand load is determined by this optional calculation are permitted to have the neutral load determined by Article 220.61 of the National Electrical Code, NFPA No. 70-2005. The loads identified in the table as “other load” and as “Remainder of other load” must include the following:
(1) 1500 volt-amperes for each 2-wire, 20-ampere small appliance branch circuit and each laundry branch circuit specified.
(2) 3 volt-amperes per square foot for general lighting and general-use receptacles.
(3) The nameplate rating of all fixed appliances, ranges, wall-mounted ovens, counter-mounted cooking units, and including 4 or more separately controlled space heating loads.
(4) The nameplate ampere or kVA rating of all motors and of all low-power-factor loads.
(5) The largest of the following:
(i) Air conditioning load;
(ii) The 65 percent diversified demand of the central electric space heating load;
(iii) The 65 percent diversified demand of the load of less than four separately-controlled electric space heating units.
(iv) The connected load of four or more separately-controlled electric space heating units.
Optional Calculation for Manufactured Homes With 110-Ampere or Larger Service
§ 3280.812   Wiring of expandable units and dual units.
(a) Expandable or multiple unit manufactured homes shall use fixed-type wiring methods and materials for connecting such units to each other.
(b) Expandable or multiple unit manufactured homes not having permanently installed feeders and which are to be moved from one location to another, shall be permitted to have disconnecting means with branch circuit protective equipment in each unit when so located that after assembly or joining together of units the requirements of § 3280.803 will be met.
§ 3280.813   Outdoor outlets, fixtures, air-conditioning equipment, etc.
(a) Outdoor fixtures and equipment shall be listed for use in wet locations, except that if located on the underside of the home or located under roof extensions or similarly protected locations, they may be listed for use in damp locations.
(b) A manufactured home provided with a branch circuit designed to energize outside heating equipment or air-conditioning equipment, other than room air conditioners, or both, located outside the manufactured home, other than room air conditioners, must have such branch-circuit conductors terminate in a listed outlet box, or disconnecting means, located on the outside of the manufactured home.
(1) A label must be permanently affixed adjacent to the outlet box. The label must be not less than 0.020-inches thick etched brass, stainless steel, anodized or alclad aluminum, or equivalent, and must not be less than 3 inches × 1 3/4 inches in size.
(2)(i) The label must include the correct voltage and ampere rating and the following information:
THIS CONNECTION IS FOR HEATING AND/OR AIR-CONDITIONING EQUIPMENT. THE BRANCH CIRCUIT IS RATED AT NOT MORE THAN____AMPERES, AT____VOLTS, 60-HERTZ,____CONDUCTOR AMPACITY. A DISCONNECTING MEANS IS LOCATED WITHIN SIGHT OF THE EQUIPMENT.
(ii) The correct voltage and ampere rating shall be given. The tag must be not less than 0.020-inches thick etched brass, stainless steel, anodized or alclad aluminum, or equivalent. The tag must have a minimum size of not less than 3 inches × 1 3/4 inches.
§ 3280.814   Painting of wiring.
During painting or staining of the manufactured home, it shall be permitted to paint metal raceways (except where grounding continuity would be reduced) or the sheath of the nonmetallic cable. Some arrangement, however, shall be made so that no paint shall be applied to the individual wires, as the color coding may be obliterated by the paint.
§ 3280.815   Polarization.
(a)(1) Except as provided in paragraph (a)(2) of this section, the white conductor must be employed for the grounded (neutral) circuit conductors only and must be connected to the white terminal or lead on receptacle outlets and fixtures. The grounded conductor must be the unswitched wire in switched circuits.
(2) A cable containing an insulated conductor with a white or natural gray outer finish or a marking of three continuous white stripes may be used for single-pole, three-way, or four-way switch loops, where this conductor is used for the supply to the switch, but not as a return conductor from the switch to the switched outlet. In these applications, the conductor with white or natural gray insulation or with three continuous white stripes must be permanently re-identified to indicate its use by painting or other effective means at its terminations and at each location where the conductor is visible and accessible.
(b) If the identified (white) conductor of a cable is used for other than grounded conductors or for other than switch loops as explained above (for a 240 volt circuit for example), the conductor shall be finished in a color other than white at each outlet where the conductors are visible and accessible.
(c) Green-colored wires or green with yellow stripe shall be used for grounding conductors only.
§ 3280.816   Examination of equipment for safety.
The examination or inspection of equipment for safety, according to this standard, shall be conducted under uniform conditions and by organizations properly equipped and qualified for experimental testing, inspections of the run of goods at factories, and service-value determinations through field examinations.
§ 3280.901   Scope.
Subpart J of this standard covers the general requirement for designing the structure of the manufactured home to fully withstand the adverse effects of transportation shock and vibration without degradation of the integrated structure or of its component parts and the specific requirements pertaining to the transportation system and its relationship to the structure.
§ 3280.902   Definitions.
(a) Chassis means the entire transportation system comprising the following subsystems: drawbar and coupling mechanism, frame, running gear assembly, and lights.
(b) Drawbar and coupling mechanism means the rigid assembly, (usually a rigid substructure) upon which is mounted a coupling mechanism, which connects the manufactured home's frame to the towing vehicle.
(c) Frame means the fabricated rigid substructure which provides considerable support to the affixed manufactured home structure both during transport and on-site; and also provides a platform for securement of the running gear assembly, the drawbar and coupling mechanism.
(d) Running gear assembly means the subsystem consisting of suspension springs, axles, bearings, wheels, hubs, tires, and brakes, with their related hardware.
(e) Lights means those safety lights and associated wiring required by applicable U.S. Department of Transportation regulations.
(f) Transportation system, (Same as chassis, above).
(g) Highway, includes all roads and streets to be legally used in transporting the manufactured home.
§ 3280.903   General requirements for designing the structure to withstand transportation shock and vibration.
(a) General. The manufactured home and its transportation system (as defined in § 3280.902(f)) must withstand the effects of highway movement such that the home is capable of being transported safely and installed as a habitable structure. Structural, plumbing, mechanical, and electrical systems must be designed to function after set-up. The home must remain weather protected during the transportation sequence to prevent internal damage.
(b) Testing or analysis requirements. Suitability of the transportation system and home structure to withstand the effects of transportation must be permitted to be determined by testing, or engineering analysis, or a combination of the two as required by paragraphs (b)(1) and (2) of this section.
(1) Road tests. Tests must be witnessed by an independent registered professional engineer or architect, manufacturer's IPIA or DAPIA, or by a recognized testing organization. Such testing procedures must be part of the manufacturer's approved design.
(2) Engineering analysis. Engineering analysis methods based on the principles of mechanics and/or structural engineering may be used to substantiate the adequacy of the transportation system to withstand in-transit loading conditions. As transportation loadings are typically critical in the longitudinal direction, analysis should, in particular, provide emphasis on design of longitudinal structural components of the manufactured home ( e.g., main chassis girder beams, sidewalls, and rim joists, etc.). Notwithstanding, all structural elements necessary to the structural integrity of the manufactured home during in-transit loading are also to be evaluated ( e.g., transverse chassis members and floor framing members, etc.).
(i)(A) The summation of the design loads in paragraphs (b)(2)(i)(A)( 1 ) through ( 3 ) of this section may be used to determine the adequacy of the chassis in conjunction with the manufactured home structure to resist in-transit loading:
( 1 ) Dead load, the vertical load due to the weight of all structural and non-structural components of the manufactured home at the time of shipment.
( 2 ) Floor load, a minimum of 3 pounds per square foot.
( 3 ) Dynamic loading factor, (0.25)[(b2iA) + (b2iB)].
(B) However, the in-transit design loading need not exceed twice the dead load of the manufactured home.
(ii) To determine the adequacy of individual longitudinal structural components to resist the in-transit design loading, a load distribution based on the relative flexural rigidity and shear stiffness of each component may be utilized. For the purpose of loading distribution, the sidewall may be considered to be acting as a “deep beam” in conjunction with other load carrying elements in determining the relative stiffness of the integrated structure. Further, by proper pre-cambering of the chassis assembly, additional loading may be distributed to the chassis, and the remaining loading may be distributed to each of the load carrying members by the relative stiffness principle.
(iii) The analysis is also to include consideration for:
(A) Location of openings in the sidewall during transport and, when appropriate,
provisions for reinforcement of the structure and/or chassis at the opening.
(B) Sidewall component member sizing and joint-splice analysis ( i.e., top and bottom plates, etc.), and connections between load carrying elements.