Page 772 - 2018_IRC

POWER AND LIGHTING DISTRIBUTION

conductors are separated from the fitting or raceway by E3906.8 Supports. Boxes and enclosures shall be supported
identified insulating material securely fastened in place. in accordance with one or more of the provisions in Sections
[300.4(G)] E3906.8.1 through E3906.8.6. (314.23)
Exception: Where threaded hubs or bosses that are an E3906.8.1 Surface mounting. An enclosure mounted on a
integral part of a cabinet, box enclosure, or raceway building or other surface shall be rigidly and securely fas-
provide a smoothly rounded or flared entry for conduc- tened in place. If the surface does not provide rigid and
tors. [300.4(G) Exception] secure support, additional support in accordance with
Conduit bushings constructed wholly of insulating other provisions of Section E3906.8 shall be provided.
material shall not be used to secure a fitting or raceway. [314.23(A)]
The insulating fitting or insulating material shall have a E3906.8.2 Structural mounting. An enclosure supported
temperature rating not less than the insulation temperature from a structural member or from grade shall be rigidly
rating of the installed conductors. [330.4(G)] supported either directly, or by using a metal, polymeric or
E3906.2 Openings. Openings through which conductors wood brace. [314.23(B)]
enter shall be closed in an approved manner. [314.17(A)] E3906.8.2.1 Nails and screws. Nails and screws,
E3906.3 Metal boxes and conduit bodies. Where raceway where used as a fastening means, shall secure boxes by
or cable is installed with metal boxes, or conduit bodies, the using brackets on the outside of the enclosure, or by
raceway or cable shall be secured to such boxes and conduit using mounting holes in the back or in a single side of
bodies. Where nonmetallic-sheathed cable or multiconductor the enclosure, or they shall pass through the interior
1
Type UF cable is used, the sheath shall extend not less than within / inch (6.4 mm) of the back or ends of the
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1 / inch (6 mm) inside the box and beyond any cable clamp. enclosure. Screws shall not be permitted to pass
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[314.17(B)] through the box except where exposed threads in the
box are protected by an approved means to avoid abra-
E3906.4 Unused openings. Unused openings other than those sion of conductor insulation. Mounting holes made in
intended for the operation of equipment, those intended for the field shall be field approved. [314.23(B)(1)]
mounting purposes, or those permitted as part of the design for
listed equipment, shall be closed to afford protection substan- E3906.8.2.2 Braces. Metal braces shall be protected
tially equivalent to that of the wall of the equipment. Metal against corrosion and formed from metal that is not less
plugs or plates used with nonmetallic boxes or conduit bodies than 0.020 inch (0.508 mm) thick uncoated. Wood
1
shall be recessed at least / inch (6.4 mm) from the outer sur- braces shall have a cross section not less than nominal 1
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face of the box or conduit body. [110.12(A)] inch by 2 inches (25.4 mm by 51 mm). Wood braces in
wet locations shall be treated for the conditions. Poly-
E3906.5 Flush-mounted installations. Installations within meric braces shall be identified as being suitable for the
or behind a surface of concrete, tile, gypsum, plaster or other use. [314.23(B)(2)]
noncombustible material, including boxes employing a flush-
type cover or faceplate shall be made so that the front edge of E3906.8.3 Mounting in finished surfaces. An enclosure
the box, plaster ring, extension ring, or listed extender will be mounted in a finished surface shall be rigidly secured there
1
set back from the finished surface not more than / inch (6.4 to by clamps, anchors, or fittings identified for the applica-
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mm). Installations within a surface of wood or other combus- tion. [314.23(C)]
tible material, boxes, plaster rings, extension rings and listed E3906.8.4 Raceway supported enclosures without
extenders shall extend to the finished surface or project there- devices or fixtures. An enclosure that does not contain a
from. (314.20) device(s), other than splicing devices, or support a lumi-
E3906.6 Noncombustible surfaces. Openings in noncom- naire, lampholder or other equipment, and that is sup-
bustible surfaces that accommodate boxes employing a flush- ported by entering raceways shall not exceed 100 cubic
3
type cover or faceplate shall be made so that there are no gaps inches (1640 cm ) in size. The enclosure shall have
1
or open spaces greater than / inch (3.2 mm) around the edge threaded entries or identified hubs. The enclosure shall be
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of the box. (314.21) supported by two or more conduits threaded wrenchtight
into the enclosure or hubs. Each conduit shall be secured
E3906.7 Surface extensions. Surface extensions shall be within 3 feet (914 mm) of the enclosure, or within 18
made by mounting and mechanically securing an extension inches (457 mm) of the enclosure if all entries are on the
ring over the box. (314.22) same side of the enclosure. [314.23(E)]
Exception: A surface extension shall be permitted to be Exception: Rigid metal, intermediate metal, or rigid
made from the cover of a flush-mounted box where the polyvinyl chloride nonmetallic conduit or electrical
cover is designed so it is unlikely to fall off, or be removed metallic tubing shall be permitted to support a conduit
if its securing means becomes loose. The wiring method body of any size, provided that the conduit body is not
shall be flexible for an approved length that permits larger in trade size than the largest trade size of the sup-
removal of the cover and provides access to the box inte- porting conduit or electrical metallic tubing. [314.23(E)
rior and shall be arranged so that any bonding or ground- Exception]
ing continuity is independent of the connection between
the box and cover. (314.22 Exception) E3906.8.5 Raceway supported enclosures, with devices
or luminaire. An enclosure that contains a device(s),
other than splicing devices, or supports a luminaire, lam-

2018 INTERNATIONAL RESIDENTIAL CODE ® 747
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