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A-5
Overview
Boxes & Covers — Steel City
®
Metallic Boxes
Table 314.16(B)
Volume Allowance Required per Conductor
SIZE OF
CONDUCTOR
(AWG)
FREE SPACE WITHIN BOX FOR EACH CONDUCTOR
CM
3
IN.
3
No. 18 24.6 1.50
No. 16 28.7 1.75
No. 14 32.8 2.00
No. 12 36.9 2.25
No. 10 41.0 2.50
No. 8 49.2 3.00
No. 6 81.9 5.00
Reprinted with permission from National Fire Protection Association NFPA70-2011.
National Electrical Code, Copyright© 2010, National Fire Protection Association, Quincy,
MA 02269. This reprinted material is not the complete and official position of the NFPA
on the referenced subject which is represented only by the standard in its entirety.
NEC
®
is a registered trademark of the National Fire Protection Association, Inc.,
Quincy, MA 02269.
Underwriters Laboratories Inc. File Number: E2969 (U.L. 514A)
Canadian Standards Association File Number: LR 12798
Federal Manufacture Number: 56501
Products designed to meet Federal Specification Number: A-A5924 (formerly W-J-800).
Verification of file numbers and compliance with federal specifications for individual items
available upon request.
Box and cover material and plating specification; .062" minimum thickness,
hot-rolled, pre-galvanized steel, minimum spangle.
ASTM G-60-U, AISI C-1008
Bracket material: All brackets except MS style; 16 gauge (.060") hot rolled, pre-
galvanized steel AISI C-1008, G-60-U. MS Style bracket; 20 gauge (.036") cold rolled
spring steel AISI C-1055, heat treated to R. 35 zinc plated .0005 thick.
Article 314 — Boxes and Fittings (continued)
Metallic Boxes — Fire Resistance Rating
Wall Penetrations
Listed single- and double-gang metallic outlet and switch boxes and
octagon ceiling boxes with metallic or non-metallic cover plates may be
used in bearing and non-bearing wood stud and steel stud walls with ratings
not exceeding 2 hours. These walls shall have gypsum wallboard facings
similar to those shown in Design Nos. U301, U411, and U425. 4 in. square
boxes may be used in 2 hr. fire rated ceilings.
The surface area of individual metallic outlet or switch boxes shall not
exceed 16 sq. in. The aggregate surface area of the boxes shall not exceed
100 sq. inches per 100 sq. ft. of wall. Boxes located on opposite sides of
walls or partitions shall be separated by a horizontal distance of 24 inches.
The metallic outlet or switch boxes shall be securely fastened to the studs
and the opening in the wallboard facing shall be cut so that the clearance
between the box and the wallboard does not exceed
1
⁄8 in.
Table 314.16(A)
Metal Boxes
MM
BOX TRADE
SIZE
(IN.)
MINIMUM
VOLUME
MAXIMUM NUMBER
OF CONDUCTORS*
CM3 IN.3 18 16 14 12 10 8 6
100 x 32 (4 x 1
1
⁄4) Round/Octagonal 205 12.5 8 7 6 5 5 5 2
100 x 38 (4 x 1
1
⁄2) Round/Octagonal 254 15.5 10 8 7 6 6 5 3
100 x 54 (4 x 2
1
⁄8) Round/Octagonal 353 21.5 14 12 10 9 8 7 4
100 x 32 (4 x 1
1
⁄4) Square 295 18.0 12 10 9 8 7 6 3
100 x 38 (4 x 1
1
⁄2) Square 344 21.0 14 12 10 9 8 7 4
100 x 54 (4 x 2
1
⁄8) Square 497 30.3 20 17 15 13 12 10 6
120 x 32 (4L x 1
1
⁄4) Square 418 25.5 17 14 12 11 10 8 5
120 x 38 (4L x 1
1
⁄2) Square 484 29.5 19 16 14 13 11 9 5
120 x 54 (4L x 2
1
⁄8) Square 689 42.0 28 24 21 18 16 14 8
75 x 50 x 38 (3 x 2 x 1
1
⁄2) Device 123 7.5 5 4 3 3 3 2 1
75 x 50 x 50 (3 x 2 x 2) Device 164 10.0 6 5 5 4 4 3 2
75 x 50 x 57 (3 x 2 x 2
1
⁄4) Device 172 10.5 7 6 5 4 4 3 2
75 x 50 x 65 (3 x 2 x 2
1
⁄2) Device 205 12.5 8 7 6 5 5 4 2
75 x 50 x 70 (3 x 2 x 2
3
⁄4) Device 230 14.0 9 8 7 6 5 4 2
75 x 50 x 90 (3 x 2 x 3
1
⁄2) Device 295 18.0 12 10 9 8 7 6 3
100 x 54 x 38 (4 x 2
1
⁄8 x 1
1
⁄2) Device 169 10.3 6 5 5 4 4 3 2
100 x 54 x 48 (4 x 2
1
⁄8 x 1
7
⁄8) Device 213 13.0 8 7 6 5 5 4 2
100 x 54 x 54 (4 x 2
1
⁄8 x 2
1
⁄8) Device 238 14.5 9 8 7 6 5 4 2
95 x 50 x 65 (3
3
⁄4 x 2 x 2
1
⁄2) Masonry Box/Gang 230 14.0 9 8 7 6 5 4 2
95 x 50 x 90 (3
3
⁄4 x 2 x 3
1
⁄2) Masonry Box/Gang 344 21.0 14 12 10 9 8 7 4
Min. 44.5 depth FS – Single-Cover/Gang (1
3
⁄4) 221 13.5 9 7 6 6 5 4 2
Min. 60.3 depth FD – Single-Cover/Gang (2
3
⁄8) 295 18.0 12 10 9 8 7 6 3
Min. 44.5 depth FS – Multiple-Cover/Gang (1
3
⁄4) 295 18.0 12 10 9 8 7 6 3
Min. 60.3 depth FD – Multiple-Cover/Gang (2
3
⁄8) 395 24.0 16 13 12 10 9 8 4
*Where no volume allowances are required by 314.16(B)(2) through 314.16(B)(5).
Underwriters Laboratories Inc. File Number: E2969 (U.L. 514A)
Canadian Standards Association File Number: LR 12798
Federal Manufacture Number: 56501 (Cage Code)
Products designed to meet Federal Specification Number: W-J-800
Verification of file numbers and compliance with federal specifications for individual items
available upon request.
Box and cover material and plating specification; .062" minimum thickness, hot rolled,
pre-galvanized steel, minimum spangle.
ASTM G-60-U, AISI C-1008
Bracket material: All brackets except MS style; 16 gauge (.060") hot rolled, pre-
galvanized steel AISI C-1008, G-90-U. MS style bracket; 20 gauge (.036") cold rolled
spring steel AISI C-1055, heat treated to R. 35 zinc plated .0005 thick.