1" EMT has 1.049" inside and 0.864 in² of area, so the 40 % fill limit is 0.346 in². It holds 35 × 14, 26 × 12, 16 × 10, 9 × 8 or 7 × 6 AWG THHN. A 60 A EV run (two 6 AWG and a 10 AWG ground) fills it 14 %: it fits.
03 · Conduit fill · Chapter 9 Tables 1, 4 & 5
USE:
1" EMT · 6.2% FILL · PASS
4 conductors take 0.0532 in² of the 0.864 in² inside 1" EMT: 6.2 % against the 40 % allowed.
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| Actions | |||||
|---|---|---|---|---|---|
| 4.5 % | 0.3068 in² | 23 | 14 | ||
| 6.2 % | 0.2924 in² | 21 | 13 | ||
| 9.8 % | 0.2612 in² | 19 | 12 | ||
| 15.2 % | 0.2147 in² | 16 | 10 | ||
| 20.0 % | 0.1724 in² | 12 | 8 | ||
| 32.8 % | 0.0618 in² | 4 | 2 | ||
| 38.0 % | 0.0171 in² | 1 | 0 | ||
| 46.1 % over | over by 0.0525 in² | — | — | ||
| 4.6 % | 0.3057 in² | 22 | 14 | ||
| 14.2 % | 0.2231 in² | 16 | 10 | ||
| 7.7 % | 0.2791 in² | 20 | 13 | ||
| 10.8 % | 0.2525 in² | 18 | 11 | ||
| 14.4 % | 0.2213 in² | 16 | 10 | ||
| 19.8 % | 0.1748 in² | 13 | 8 | ||
| 24.9 % | 0.1302 in² | 9 | 6 |
gnd: Table 250.122 ground. 1" EMT allows 0.346 in² at 40 %.
05 / Field guide
1" EMT has 1.049" inside and 0.864 in² of area, so the 40 % fill limit is 0.346 in². It holds 35 × 14, 26 × 12, 16 × 10, 9 × 8 or 7 × 6 AWG THHN. A 60 A EV run (two 6 AWG and a 10 AWG ground) fills it 14 %: it fits.
1" EMT (Article 358) has 0.864 in² inside. One conductor may fill 53 % (0.458 in²), two 31 % (0.268 in²), three or more 40 % (0.346 in²). A nipple 24" or shorter may take 60 % (0.519 in²): 39 × 12 AWG.
fill % = Σ Table 5 areas ÷ 0.864 in²
1" EMT is 1.163" outside and 1.049" inside, a 0.057" wall; the steel is an equipment grounding path (250.118).
Secure 1" EMT within 3 ft of each box and support it at least every 10 ft (358.30). At 67 lb per 100 ft, each 10 ft span hangs 6.7 lb of pipe. A 60 A EV run leaves room for 16 more 12 AWG THHN; a 60 A subpanel feeder leaves room for 12.
For a mix, add the areas. Two 6 AWG and a 10 AWG ground (a 60 A EV run) take 0.1225 in², 14.2 %; three 3 AWG and an 8 AWG (a 100 A subpanel) take 0.3285 in², 38.0 %.
Questions
26 THHN conductors at the 40 % limit (0.346 in² ÷ 0.0133 in²); 26 current-carrying 12 AWG are derated to 45 % (310.15(C)(1)).
16 THHN, or 14 XHHW (thicker insulation, 0.0243 in² against 0.0211 in²).
Within 3 ft of every box or fitting and at least every 10 ft along the run (NEC 358.30): a 50 ft straight run takes 6 straps, a 100 ft run 11. Keep the bends between pull points to 360° or less (358.26).
Three 6 AWG THHN and a 10 AWG ground take 0.1732 in², 20.0 % of 0.864 in²: that fits the 40 % limit.
1.049 inch nominal (NEC Chapter 9 Table 4), 1.163 inch outside. Use the inside area, 0.864 in², for fill.
2 AWG THHN: three fit within 40 %.
EMT is the reference: 1" EMT has 0.864 in² inside.