1/2" EMT has 0.622" inside and 0.304 in² of area, so the 40 % fill limit is 0.122 in². It holds 12 × 14, 9 × 12, 5 × 10, 3 × 8 or 2 × 6 AWG THHN. A 60 A EV run (two 6 AWG and a 10 AWG ground) fills it 40 %: too full.
03 · Conduit fill · Chapter 9 Tables 1, 4 & 5
USE:
1/2" EMT · 17.5% FILL · PASS
4 conductors take 0.0532 in² of the 0.304 in² inside 1/2" EMT: 17.5 % against the 40 % allowed.
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| Actions | |||||
|---|---|---|---|---|---|
| 12.8 % | 0.0828 in² | 6 | 3 | ||
| 17.5 % | 0.0684 in² | 5 | 3 | ||
| 27.8 % | 0.0372 in² | 2 | 1 | ||
| 43.1 % over | over by 0.0093 in² | — | — | ||
| 13.1 % | 0.0817 in² | 6 | 3 | ||
| 21.9 % | 0.0551 in² | 4 | 2 | ||
| 30.6 % | 0.0285 in² | 2 | 1 |
gnd: Table 250.122 ground. 1/2" EMT allows 0.122 in² at 40 %.
05 / Field guide
1/2" EMT has 0.622" inside and 0.304 in² of area, so the 40 % fill limit is 0.122 in². It holds 12 × 14, 9 × 12, 5 × 10, 3 × 8 or 2 × 6 AWG THHN. A 60 A EV run (two 6 AWG and a 10 AWG ground) fills it 40 %: too full.
1/2" EMT (Article 358) has 0.304 in² inside. One conductor may fill 53 % (0.161 in²), two 31 % (0.094 in²), three or more 40 % (0.122 in²). A nipple 24" or shorter may take 60 % (0.182 in²): 13 × 12 AWG.
fill % = Σ Table 5 areas ÷ 0.304 in²
1/2" EMT is 0.706" outside and 0.622" inside, a 0.042" wall; the steel is an equipment grounding path (250.118).
Secure 1/2" EMT within 3 ft of each box and support it at least every 10 ft (358.30). At 30 lb per 100 ft, each 10 ft span hangs 3.0 lb of pipe. A 60 A EV run (40.3 %) does not fit; nor does a 60 A subpanel feeder (57.0 %).
For a mix, add the areas. Two 6 AWG and a 10 AWG ground (a 60 A EV run) take 0.1225 in², 40.3 %; three 3 AWG and an 8 AWG (a 100 A subpanel) take 0.3285 in², 108.1 %.
Questions
9 THHN conductors at the 40 % limit (0.122 in² ÷ 0.0133 in²); 9 current-carrying 12 AWG are derated to 70 % (310.15(C)(1)).
5 THHN, or 5 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, 57.0 % of 0.304 in²: over the 40 % limit; use 3/4" EMT.
0.622 inch nominal (NEC Chapter 9 Table 4), 0.706 inch outside. Use the inside area, 0.304 in², for fill.
8 AWG THHN: three fit within 40 %.
EMT is the reference: 1/2" EMT has 0.304 in² inside.