Maximum number of THHN/THWN-2 conductors in EMT (Electrical Metallic Tubing), trade sizes 1/2 inch through 4 inch. Internal areas from NEC Chapter 9, Table 4; fill limits from Table 1 (53% for one conductor, 31% for two, 40% for three or more). NEC Article 358.
| Trade size | 40% area (in²) | 14 | 12 | 10 | 8 | 6 | 4 | 2 | 1/0 | 2/0 | 4/0 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2" | 0.122 | 12 | 9 | 5 | 3 | 1 | 1 | 1 | — | — | — |
| 3/4" | 0.213 | 21 | 16 | 10 | 5 | 4 | 2 | 1 | 1 | 1 | — |
| 1" | 0.346 | 35 | 26 | 16 | 9 | 6 | 4 | 2 | 1 | 1 | 1 |
| 1-1/4" | 0.598 | 61 | 44 | 28 | 16 | 11 | 7 | 5 | 3 | 2 | 1 |
| 1-1/2" | 0.814 | 83 | 61 | 38 | 22 | 16 | 9 | 7 | 4 | 3 | 1 |
| 2" | 1.342 | 138 | 100 | 63 | 36 | 26 | 16 | 11 | 7 | 6 | 4 |
| 2-1/2" | 2.343 | 241 | 176 | 111 | 64 | 46 | 28 | 20 | 12 | 10 | 7 |
| 3" | 3.538 | 364 | 266 | 167 | 96 | 69 | 42 | 30 | 19 | 15 | 10 |
| 3-1/2" | 4.618 | 476 | 347 | 218 | 126 | 91 | 56 | 39 | 24 | 20 | 14 |
| 4" | 5.901 | 608 | 443 | 279 | 161 | 116 | 71 | 50 | 31 | 26 | 18 |
Column headings are AWG conductor sizes, all THHN/THWN-2. A dash means the conductor does not fit even as a single conductor at the 53% limit.
Thin-wall steel tubing, the most common raceway in commercial interiors and exposed residential work. Joined with set-screw or compression couplings, never threaded.