The volume of a wiring enclosure (box) shall be the total volume of the assembled sections and, where used, the space provided by plaster rings, domed covers, extension rings, and so forth, that are marked with their volume or are made from boxes the dimensions of which are listed in Table 314.16(A). Where a box is provided with one or more securely installed barriers, the volume shall be apportioned to each of the resulting spaces. Each barrier, if not marked with its volume, shall be considered to take up 8.2 cm3 (1/2 in.3) if metal, and 16.4 cm3 (1.0 in.3) if nonmetallic.
Table 314.16(A) Metal Boxes
| Box Trade Size | Minimum Volume | Maximum Number of Conductors* (arranged by AWG size) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| mm | in. | cm3 | in.3 | 18 | 16 | 14 | 12 | 10 | 8 | 6 | |
| 100 × 32 | (4 × 11/4) | round/octagonal | 205 | 12.5 | 8 | 7 | 6 | 5 | 5 | 4 | 2 |
| 100 × 38 | (4 × 11/2) | round/octagonal | 254 | 15.5 | 10 | 8 | 7 | 6 | 6 | 5 | 3 |
| 100 × 54 | (4 × 21/8) | round/octagonal | 353 | 21.5 | 14 | 12 | 10 | 9 | 8 | 7 | 4 |
| 100 × 32 | (4 × 11/4) | square | 295 | 18.0 | 12 | 10 | 9 | 8 | 7 | 6 | 3 |
| 100 × 38 | (4 × 11/2) | square | 344 | 21.0 | 14 | 12 | 10 | 9 | 8 | 7 | 4 |
| 100 × 54 | (4 × 21/8) | square | 497 | 30.3 | 20 | 17 | 15 | 13 | 12 | 10 | 6 |
| 120 × 32 | (411/16× 11/4) | square | 418 | 25.5 | 17 | 14 | 12 | 11 | 10 | 8 | 5 |
| 120 × 38 | (411/16× 11/2) | square | 484 | 29.5 | 19 | 16 | 14 | 13 | 11 | 9 | 5 |
| 120 × 54 | (411/16× 21/8) | square | 689 | 42.0 | 28 | 24 | 21 | 18 | 16 | 14 | 8 |
| 75 × 50 × 38 | (3 × 2 × 11/2) | device | 123 | 7.5 | 5 | 4 | 3 | 3 | 3 | 2 | 1 |
| 75 × 50 × 50 | (3 × 2 × 2) | device | 164 | 10.0 | 6 | 5 | 5 | 4 | 4 | 3 | 2 |
| 75 × 50 × 57 | (3 × 2 × 21/4) | device | 172 | 10.5 | 7 | 6 | 5 | 4 | 4 | 3 | 2 |
| 75 × 50 × 65 | (3 × 2 × 21/4) | device | 205 | 12.5 | 8 | 7 | 6 | 5 | 5 | 4 | 2 |
| 75 × 50 × 70 | (3 × 2 × 23/4) | device | 230 | 14.0 | 9 | 8 | 7 | 6 | 5 | 4 | 2 |
| 75 × 50 × 90 | (3 × 2 × 31/2) | device | 295 | 18.0 | 12 | 10 | 9 | 8 | 7 | 6 | 3 |
| 100 × 54 × 38 | (4 × 21/8 × 11/2) | device | 169 | 10.3 | 6 | 5 | 5 | 4 | 4 | 3 | 2 |
| 100 × 54 × 48 | (4 × 21/8 × 17/8) | device | 213 | 13.0 | 8 | 7 | 6 | 5 | 5 | 4 | 2 |
| 100 × 54 × 54 | (4 × 21/8 × 21/8) | device | 238 | 14.5 | 9 | 8 | 7 | 6 | 5 | 4 | 2 |
| 95 × 50 × 65 | (33/4 × 2 × 21/2) | masonry box/gang | 230 | 14.0 | 9 | 8 | 7 | 6 | 5 | 4 | 2 |
| 95 × 50 × 90 | (33/4 × 2 × 31/2) | masonry box/gang | 344 | 21.0 | 14 | 12 | 10 | 9 | 8 | 7 | 4 |
| min. 44.5 depth | FS - single cover/gang (13/4) | 221 | 13.5 | 9 | 7 | 6 | 6 | 5 | 4 | 2 | |
| min. 60.3 depth | FD - single cover/gang (23/8) | 295 | 18.0 | 12 | 10 | 9 | 8 | 7 | 6 | 3 | |
| min. 44.5 depth | FS - multiple cover/gang (13/4) | 295 | 18.0 | 12 | 10 | 9 | 8 | 7 | 6 | 3 | |
| min. 60.3 depth | FD - multiple cover/gang (23/8) | 395 | 24.0 | 16 | 13 | 12 | 10 | 9 | 8 | 4 | |
*Where no volume allowances are required by 314.16(B)(2) through (B)(6).
