Page 770 - 2018_IRC

POWER AND LIGHTING DISTRIBUTION

structure or, in underground circuits, without excavating side- tion E3905.12.3. The provisions of this section shall not
walks, paving, earth or other substance used to establish the apply to terminal housings supplied with motors or genera-
finished grade. (314.29) tors. (314.16)
Exception: Boxes covered by gravel, light aggregate or E3905.12.1 Box volume calculations. The volume of a
noncohesive granulated soil shall be listed for the applica- wiring enclosure (box) shall be the total volume of the
tion, and the box locations shall be effectively identified assembled sections, and, where used, the space provided
and access shall be provided for excavation. (314.29 by plaster rings, domed covers, extension rings, etc., that
Exception) are marked with their volume in cubic inches or are made
E3905.11 Damp or wet locations. In damp or wet locations, from boxes the dimensions of which are listed in Table
boxes, conduit bodies and fittings shall be placed or equipped E3905.12.1. Where a box is provided with one or more
so as to prevent moisture from entering or accumulating securely installed barriers, the volume shall be appor-
within the box, conduit body or fitting. Boxes, conduit bodies tioned to each of the resulting spaces. Each barrier, if not
and fittings installed in wet locations shall be listed for use in marked with its volume, shall be considered to take up to
3
wet locations. 0.5 cubic inch (8.2 cm ) if metal, and 1.0 cubic inch (16.4
3
cm ) if nonmetallic. [314.16(A)]
Where drainage openings are installed in the field in boxes
or conduit bodies listed for use in damp or wet locations, such E3905.12.1.1 Standard boxes. The volumes of standard
1
openings shall be approved, not smaller than / inch (3 mm) boxes that are not marked with a cubic-inch capacity
8
1
and not larger than / inch (6.4 mm). For listed drain fittings, shall be as given in Table E3905.12.1. [314.16(A)(1)]
4
larger openings are permitted where installed in the field in E3905.12.1.2 Other boxes. Boxes 100 cubic inches
accordance with the manufacturer’s instructions. (314.15) (1640 cm ) or less, other than those described in Table
3
E3905.12 Number of conductors in outlet, device, and E3905.12.1, and nonmetallic boxes shall be durably
junction boxes, and conduit bodies. Boxes and conduit bod- and legibly marked by the manufacturer with their
ies shall be of an approved size to provide free space for all cubic-inch capacity. Boxes described in Table
enclosed conductors. In no case shall the volume of the box, E3905.12.1 that have a larger cubic inch capacity than
as calculated in Section E3905.12.1, be less than the box fill is designated in the table shall be permitted to have
calculation as calculated in Section E3905.12.2. The mini- their cubic-inch capacity marked as required by this
mum volume for conduit bodies shall be as calculated in Sec- section. [314.16(A)(2)]
TABLE E3905.12.1 [Table 314.16(A)]
MAXIMUM NUMBER OF CONDUCTORS IN METAL BOXES a
BOX DIMENSIONS MAXIMUM CAPACITY MAXIMUM NUMBER OF CONDUCTORS a
(inches trade size and type) (cubic inches) 18 Awg 16 Awg 14 Awg 12 Awg 10 Awg 8 Awg 6 Awg
4 × 1 / round or octagonal 12.5 8 7 6 5 5 4 2
1
4
1
4 × 1 / round or octagonal 15.5 10 8 7 6 6 5 3
2
1
4 × 2 / round or octagonal 21.5 14 12 10 9 8 7 4
8
1
4 × 1 / square 18.0 12 10 9 8 7 6 3
4
4 × 1 / square 21.0 14 12 10 9 8 7 4
1
2
4 × 2 / square 30.3 20 17 15 13 12 10 6
1
8
4 / × / square 25.5 17 14 12 11 10 8 5
11
11
16 4
4 / × / square 29.5 19 16 14 13 11 9 5
11
11
16 2
1
11
4 / × 2 / square 42.0 28 24 21 18 16 14 8
16 8
3 × 2 × 1 / devi 7.5 5 4 3 3 3 2 1
1
2
3 × 2 × 2 device 10.0 6 5 5 4 4 3 2
1
3 × 2 × 2 / device 10.5 7 6 5 4 4 3 2
4
3 × 2 × 2 / device 12.5 8 7 6 5 5 4 2
1
2
3 × 2 × 2 / device 14.0 9 8 7 6 5 4 2
3
4
3 × 2 × 3 / devi 18.0 12 10 9 8 7 6 3
1
2
1
4 × 2 / × 1 / device 10.3 6 5 5 4 4 3 2
1
8 2
1
7
4 × 2 / × 1 / device 13.0 8 7 6 5 5 4 2
8 8
1
1
4 × 2 / × 2 / device 14.5 9 8 7 6 5 4 2
8 8
3
3 / × 2 × 2 / masonry box/gang 14.0 9 8 7 6 5 4 2
1
4 2
3 / × 2 × 3 / masonry box/gang 21.0 14 12 10 9 8 7 4
3
1
4 2
For SI: 1 inch = 25.4 mm, 1 cubic inch = 16.4 cm . 3
a. Where volume allowances are not required by Sections E3905.12.2.2 through E3905.12.2.5.
2018 INTERNATIONAL RESIDENTIAL CODE ® 745
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