3/4" PVC Schedule 80 has 0.722" inside and 0.409 in² of area, so the 40 % fill limit is 0.164 in². It holds 17 × 14, 12 × 12, 7 × 10, 4 × 8 or 3 × 6 AWG THHN. A 60 A EV run (two 6 AWG and a 10 AWG ground) fills it 30 %: it fits.
03 · Conduit fill · Chapter 9 Tables 1, 4 & 5
USE:
3/4" PVC 80 · 13.0% FILL · PASS
4 conductors take 0.0532 in² of the 0.409 in² inside 3/4" PVC 80: 13.0 % against the 40 % allowed.
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| Actions | |||||
|---|---|---|---|---|---|
| 9.5 % | 0.1248 in² | 9 | 5 | ||
| 13.0 % | 0.1104 in² | 8 | 5 | ||
| 20.6 % | 0.0792 in² | 5 | 3 | ||
| 32.0 % | 0.0327 in² | 2 | 1 | ||
| 42.3 % over | over by 0.0096 in² | — | — | ||
| 9.8 % | 0.1237 in² | 9 | 5 | ||
| 30.0 % | 0.0411 in² | 3 | 1 | ||
| 16.3 % | 0.0971 in² | 7 | 4 | ||
| 22.8 % | 0.0705 in² | 5 | 3 | ||
| 30.4 % | 0.0393 in² | 2 | 1 |
gnd: Table 250.122 ground. 3/4" PVC 80 allows 0.164 in² at 40 %.
05 / Field guide
3/4" PVC Schedule 80 has 0.722" inside and 0.409 in² of area, so the 40 % fill limit is 0.164 in². It holds 17 × 14, 12 × 12, 7 × 10, 4 × 8 or 3 × 6 AWG THHN. A 60 A EV run (two 6 AWG and a 10 AWG ground) fills it 30 %: it fits.
3/4" PVC Schedule 80 (Article 352) has 0.409 in² inside. One conductor may fill 53 % (0.217 in²), two 31 % (0.127 in²), three or more 40 % (0.164 in²). A nipple 24" or shorter may take 60 % (0.246 in²): 18 × 12 AWG.
fill % = Σ Table 5 areas ÷ 0.409 in²
Schedule 80 is for runs exposed to physical damage (352.10(F)). The heavier wall leaves 0.409 in² inside against 0.508 in² for Schedule 40 of the same size.
Secure 3/4" PVC Schedule 80 within 3 ft of each box and support it at least every 3 ft (352.30). A 60 A EV run leaves room for 3 more 12 AWG THHN; nor does a 60 A subpanel feeder (42.3 %).
For a mix, add the areas. Two 6 AWG and a 10 AWG ground (a 60 A EV run) take 0.1225 in², 30.0 %; three 3 AWG and an 8 AWG (a 100 A subpanel) take 0.3285 in², 80.3 %.
Questions
12 THHN conductors at the 40 % limit (0.164 in² ÷ 0.0133 in²); 12 current-carrying 12 AWG are derated to 50 % (310.15(C)(1)).
7 THHN, or 6 XHHW (thicker insulation, 0.0243 in² against 0.0211 in²).
Within 3 ft of every box or fitting and at least every 3 ft along the run (NEC 352.30, Table 352.30): a 50 ft straight run takes 16 straps, a 100 ft run 33. Keep the bends between pull points to 360° or less (352.26).
Three 6 AWG THHN and a 10 AWG ground take 0.1732 in², 42.3 % of 0.409 in²: over the 40 % limit; use 1" PVC 80.
0.722 inch nominal (NEC Chapter 9 Table 4), 1.050 inch outside. Use the inside area, 0.409 in², for fill.
6 AWG THHN: three fit within 40 %.
23 % smaller than 3/4" EMT (0.533 in²): the thick wall of Schedule 80 costs inside room.