Maximum number of THHN/THWN-2 conductors in PVC Conduit, Schedule 40, 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 352.
| Trade size | 40% area (in²) | 14 | 12 | 10 | 8 | 6 | 4 | 2 | 1/0 | 2/0 | 4/0 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2" | 0.114 | 11 | 8 | 5 | 3 | 1 | 1 | 1 | — | — | — |
| 3/4" | 0.203 | 20 | 15 | 9 | 5 | 4 | 1 | 1 | 1 | 1 | — |
| 1" | 0.333 | 34 | 25 | 15 | 9 | 6 | 4 | 2 | 1 | 1 | 1 |
| 1-1/4" | 0.581 | 59 | 43 | 27 | 15 | 11 | 7 | 5 | 3 | 2 | 1 |
| 1-1/2" | 0.794 | 81 | 59 | 37 | 21 | 15 | 9 | 6 | 4 | 3 | 1 |
| 2" | 1.316 | 135 | 98 | 62 | 35 | 25 | 15 | 11 | 7 | 5 | 4 |
| 2-1/2" | 1.878 | 193 | 141 | 89 | 51 | 37 | 22 | 16 | 10 | 8 | 5 |
| 3" | 2.907 | 299 | 218 | 137 | 79 | 57 | 35 | 25 | 15 | 13 | 8 |
| 3-1/2" | 3.895 | 401 | 292 | 184 | 106 | 76 | 47 | 33 | 20 | 17 | 12 |
| 4" | 5.022 | 517 | 377 | 238 | 137 | 99 | 60 | 43 | 27 | 22 | 15 |
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.
Rigid nonmetallic conduit, solvent-welded. The default for underground runs, wet locations, and corrosive environments. Schedule 80 has thicker walls and therefore less usable fill area.