3/4" EMT has 0.824" inside and 0.533 in² of area, so the 40 % fill limit is 0.213 in². It holds 22 × 14, 16 × 12, 10 × 10, 6 × 8 or 4 × 6 AWG THHN. A 60 A EV run (two 6 AWG and a 10 AWG ground) fills it 23 %: it fits.
03 · Conduit fill · Chapter 9 Tables 1, 4 & 5
USE:
3/4" EMT · 10.0% FILL · PASS
4 conductors take 0.0532 in² of the 0.533 in² inside 3/4" EMT: 10.0 % against the 40 % allowed.
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| Actions | |||||
|---|---|---|---|---|---|
| 7.3 % | 0.1744 in² | 13 | 8 | ||
| 10.0 % | 0.1600 in² | 12 | 7 | ||
| 15.8 % | 0.1288 in² | 9 | 6 | ||
| 24.6 % | 0.0823 in² | 6 | 3 | ||
| 32.5 % | 0.0400 in² | 3 | 1 | ||
| 53.2 % over | over by 0.0706 in² | — | — | ||
| 7.5 % | 0.1733 in² | 13 | 8 | ||
| 23.0 % | 0.0907 in² | 6 | 4 | ||
| 12.5 % | 0.1467 in² | 11 | 6 | ||
| 17.5 % | 0.1201 in² | 9 | 5 | ||
| 23.3 % | 0.0889 in² | 6 | 4 | ||
| 32.0 % | 0.0424 in² | 3 | 2 |
gnd: Table 250.122 ground. 3/4" EMT allows 0.213 in² at 40 %.
05 / Field guide
3/4" EMT has 0.824" inside and 0.533 in² of area, so the 40 % fill limit is 0.213 in². It holds 22 × 14, 16 × 12, 10 × 10, 6 × 8 or 4 × 6 AWG THHN. A 60 A EV run (two 6 AWG and a 10 AWG ground) fills it 23 %: it fits.
3/4" EMT (Article 358) has 0.533 in² inside. One conductor may fill 53 % (0.283 in²), two 31 % (0.165 in²), three or more 40 % (0.213 in²). A nipple 24" or shorter may take 60 % (0.32 in²): 24 × 12 AWG.
fill % = Σ Table 5 areas ÷ 0.533 in²
3/4" EMT is 0.922" outside and 0.824" inside, a 0.049" wall; the steel is an equipment grounding path (250.118).
Secure 3/4" EMT within 3 ft of each box and support it at least every 10 ft (358.30). At 46 lb per 100 ft, each 10 ft span hangs 4.6 lb of pipe. A 60 A EV run leaves room for 6 more 12 AWG THHN; a 60 A subpanel feeder leaves room for 3.
For a mix, add the areas. Two 6 AWG and a 10 AWG ground (a 60 A EV run) take 0.1225 in², 23.0 %; three 3 AWG and an 8 AWG (a 100 A subpanel) take 0.3285 in², 61.6 %.
Questions
16 THHN conductors at the 40 % limit (0.213 in² ÷ 0.0133 in²); 16 current-carrying 12 AWG are derated to 50 % (310.15(C)(1)).
10 THHN, or 8 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, 32.5 % of 0.533 in²: that fits the 40 % limit.
0.824 inch nominal (NEC Chapter 9 Table 4), 0.922 inch outside. Use the inside area, 0.533 in², for fill.
6 AWG THHN: three fit within 40 %.
EMT is the reference: 3/4" EMT has 0.533 in² inside.