bstantial brace. Snap-in type boxes
provided with special wall or ceiling
brackets that securely fasten boxes in
walls or ceilings shall be permitted.
(o) Outlet boxes shall fit closely to
openings in combustible walls and ceil-
ings, and they shall be flush with such
surfaces.
(p) Appliances having branch-circuit
terminal connections which operate at
temperatures higher than 60
°
C (140
°
F)
shall have circuit conductors as de-
scribed in paragraphs (p) (1) and (2) of
this section:
(1) Branch-circuit conductors having
an insulation suitable for the tempera-
ture encountered shall be permitted to
run directly to the appliance.
(2) Conductors having an insulation
suitable for the temperature encoun-
tered shall be run from the appliance
terminal connections to a readily ac-
cessible outlet box placed at least one
foot from the appliance. These conduc-
tors shall be in a suitable raceway
which shall extend for at least 4 feet.
(q) A substantial brace for securing a
box, fitting or cabinet shall be as de-
scribed in the National Electrical Code,
NFPA 701993 Article 37013(d), or the
brace, including the fastening mecha-
nism to attach the brace to the home
structure, shall withstand a force of 50
lbs. applied to the brace at the in-
tended point(s) of attachment for the
box in a direction perpendicular to the
surface in which the box is installed.
(r) Outlet boxes shall fit closely to
the openings in combustible wall and
ceilings with a maximum of a
1 8
inch
gap. They shall be flush with the finish
surface or project therefrom.
(s) Where the sheathing of NM cable
has been cut or damaged and visual in-
spection reveals that the conductor
and its insulation has not been dam-
aged, it shall be permitted to repair the
cable sheath with electrical tape which
provides equivalent protection to the
sheath.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44
FR 20679, Apr. 6, 1979, as amended at 58 FR
55020, Oct. 25, 1993]
§ 3280.809
Grounding.
(a)
General. Grounding of both elec-
trical and nonelectrical metal parts in
a manufactured home shall be through
connection to a grounding bus in the
manufactured home distribution panel-
board. 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 lo-
cation. Neither the frame of the manu-
factured home nor the frame of any ap-
pliance shall be connected to the neu-
tral conductor in the manufactured
home.
(b)
Insulated neutral. (1) The grounded
circuit conductor (neutral) shall be in-
sulated from the grounding conductors
and from equipment enclosures and
other grounded parts. The grounded
(neutral) circuit terminals in the dis-
tribution panelboard and in ranges,
clothes dryers, counter-mounted cook-
ing 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 dis-
carded. However, when service equip-
ment 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 pan-
elboard or disconnecting means.
(2) In the electrical system, all ex-
posed metal parts, enclosures, frames,
lamp fixture canopies, etc., shall be ef-
fectively bonded to the grounding ter-
minal 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
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24 CFR Ch. XX (5101 Edition)
§ 3280.810
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 ac-
cessible terminal on the chassis.
(2) Grounding terminals shall be of
the solderless type and approved as
pressure-terminal connectors recog-
nized for the wire size used. Star wash-
ers 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 con-
figuration 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 chas-
sis (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 an-
other 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 se-
cured 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-pen-
etrating fittings (such as screws and
star washers or equivalent).
[40 FR 58752, Dec. 18, 1975. Redesignated at 44
FR 20679, Apr. 6, 1979, as amended at 58 FR
55020, Oct. 25, 1993]
§ 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 sec-
ond. 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) Each manufactured home shall be
subject to:
(1) A continuity test to assure that
metallic parts are properly bonded;
(2) Operational test to demonstrate
that all equipment, except water heat-
ers, electric furnaces, dishwashers,
clothes washers/dryers, and portable
appliances, is connected and in work-
ing order; and
(3) Polarity checks to determine that
connections have been properly made.
Visual verification shall be an accept-
able check.
[58 FR 55020, Oct. 25, 1993]
§ 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 manufac-
tured 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 (out-
side 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-am-
peres for each 20-ampere appliance re-
ceptacle circuit (see definition of Ap-
pliance Portable with Note): e.g.
Number of circuits
×
1,500=small appli-
ance 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
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