Rigid PVC conduit, Schedule 40 fill chart
The most THHN wires of one size each PVC Sch 40 size may hold, with three or more wires at 40 % fill. Pick a size for XHHW-2 and THW as well.
| Trade size | Inside area | 40 % | #14 | #12 | #10 | #8 | #6 | #4 | #2 | #1/0 | #4/0 | 250 kcmil | 500 kcmil |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2" | 0.285 | 0.114 | 11 | 8 | 5 | 3 | 1 | 1 | 1 | 0 | 0 | 0 | 0 |
| 3/4" | 0.508 | 0.203 | 21 | 15 | 9 | 5 | 4 | 1 | 1 | 1 | 0 | 0 | 0 |
| 1" | 0.832 | 0.333 | 34 | 25 | 15 | 9 | 6 | 4 | 3 | 1 | 1 | 1 | 0 |
| 1-1/4" | 1.453 | 0.581 | 60 | 43 | 27 | 16 | 11 | 7 | 5 | 3 | 1 | 1 | 1 |
| 1-1/2" | 1.986 | 0.794 | 82 | 59 | 37 | 21 | 15 | 9 | 7 | 4 | 1 | 1 | 1 |
| 2" | 3.291 | 1.316 | 135 | 99 | 62 | 36 | 26 | 16 | 11 | 7 | 4 | 3 | 1 |
| 2-1/2" | 4.695 | 1.878 | 193 | 141 | 89 | 51 | 37 | 22 | 16 | 10 | 6 | 4 | 2 |
| 3" | 7.268 | 2.907 | 299 | 218 | 137 | 79 | 57 | 35 | 25 | 15 | 9 | 7 | 4 |
| 3-1/2" | 9.737 | 3.895 | 401 | 293 | 184 | 106 | 77 | 47 | 33 | 21 | 12 | 10 | 5 |
| 4" | 12.554 | 5.022 | 517 | 377 | 238 | 137 | 99 | 61 | 43 | 27 | 15 | 12 | 7 |
| 5" | 19.761 | 7.904 | 815 | 594 | 374 | 216 | 156 | 96 | 68 | 42 | 24 | 20 | 11 |
| 6" | 28.567 | 11.427 | 1178 | 859 | 541 | 312 | 225 | 138 | 98 | 61 | 35 | 28 | 16 |
Areas in square inches, from Chapter 9, Table 4 (2023 NEC). THHN/THWN-2 areas from Table 5.
About PVC Sch 40
Schedule 40 is the standard PVC wall. Support spacing gets wider as the size goes up (Table 352.30), and long runs in the sun need expansion fittings (352.44). See strap spacing and the fill rules.