Dimension, capacity, and maximum conductors of metal boxes

Tables > Metal Boxes > Dimensions and Sizes > Capacity, max conductors

Jump to: Description Table Copyright Projects

Box Dimension, Inches Trade Size Or Type	Min. Cu. In. Capacity
		Maximum Number Of Conductors
		No. 18	No. 16	No. 14	No. 12	No. 10	No. 8	No. 6
4 X 1-1/4 ROUND OR OCTAGONAL	12.5	8	7	6	5	5	4	2
4 X 1-1/2 ROUND OR OCTAGONAL	15.5	10	8	7	6	6	5	3
4 X 2-1/8 ROUND OR OCTAGONAL	21.5	14	12	10	9	8	7	4
4 X 1-1/4 SQUARE	18	12	10	9	8	7	6	3
4 X 1-1/2 SQUARE	21	14	12	10	9	8	7	4
4 X 2-1/8 SQUARE	30.3	20	17	15	13	12	10	6
4-11/16 X 1-1/4 SQUARE	25.5	17	14	12	11	10	8	5
4-11/16 X 1-1/2 SQUARE	29.5	19	16	14	13	11	9	5
4-11/16 X 2-1/8 SQUARE	42.0	28	24	21	18	16	14	8
3 X 2 X 1-1/2 DEVICE	7.5	5	4	3	3	3	2	1
3 X 2 X 2 DEVICE	10	6	5	5	4	4	3	2
3 X 2 X 2-1/4 DEVICE	10.5	7	6	5	4	4	3	2
3 X 2 X 2-1/2 DEVICE	12.5	8	7	6	5	5	4	2
3 X 2 X 2-3/4 DEVICE	14.0	9	8	7	6	5	4	2
3 X 2 X 3-1/2 DEVICE	18	12	10	9	8	7	6	3
4 X 2-1/8 X 1-1/2 DEVICE	10.3	6	5	5	4	4	3	2
4 X 2-1/8 X 1-7/8 DEVICE	13.0	8	7	6	5	5	4	2
4 X 2-1/8 X 2-1/8 DEVICE	14.5	9	8	7	6	5	4	2
3-3/4 X 2 X 2-1/2 MASONARY BOX	14.0	9	8	7	6	5	4	2
3-3/4 X 2 X 3-1/2 MASONARY BOX	21.0	14	12	10	9	8	7	4
FS-MINIMUM INTERNAL DEPTH 1-3/4 SINGLE COVER/GANG	13.5	9	7	6	6	5	4	2
FD-MINIMUM INTERNAL DEPTH 2-3/8 SINGLE COVER/GANG	18.0	12	10	9	8	7	6	3
FS-MINIMUM INTERNAL DEPTH 1-3/4 MULTIPLE COVER/GANG	18.0	12	10	9	8	7	6	3
FD-MINIMUM INTERNAL DEPTH 2-3/8 MULTIPLE COVER/GANG	24	16	13	12	10	9	8	4

Reprinted with permission from NFPA 70-1999, the National Electrical Code®, Copyright 1998, National Fire Protection Association, Quincy, MA 02269. This reprinted material is not the referenced subject which is represented only by the Standard in its entirety.