How many #4 THHN fit in 2-1/2" EMT?
284 AWG THHN/THWN-2 wires in 2-1/2" Electrical metallic tubing
5.858 sq in × 40 % = 2.3432 sq in allowed. ÷ 0.0824 sq in per wire = 28.44, so 28.
This pull in numbers
- 28 wires fill
- 39.4 % of 2-1/2" EMT
- Limit for three or more
- 40 %
- For 29 or more
- 3" EMT, up to 43
- Pipe to wire diameter
- 8.43 to 1
- In THW insulation
- 24 fit
- In XHHW-2 insulation
- 28 fit
Before you pull 28
- The ground counts. Every wire in the pipe counts toward fill, the green or bare ground and the neutrals too. 28 is the total, not the hots.
- Derating. If all 28 were current-carrying, each would be adjusted to 45 % of its ampacity (Table 310.15(C)(1)): a #4 THHN at 95 A in the 90 °C column becomes 42.8 A. Grounds don't count as current-carrying. How derating works
- Bends. A full pipe pulls hard. Keep to 360° of bends between pull points, less for a tight fill.
#4 THHN in other 2-1/2" conduit
| Conduit | Inside area | Most #4 THHN |
|---|---|---|
| Electrical metallic tubing | 5.858 | 28 |
| Intermediate metal conduit | 5.135 | 25 |
| Rigid metal conduit (RMC, GRC) | 4.866 | 23 |
| Rigid PVC conduit, Schedule 40 | 4.695 | 22 |
| Rigid PVC conduit, Schedule 80 | 4.119 | 20 |
| Flexible metal conduit (FMC, Greenfield) | 4.909 | 24 |
| Liquidtight flexible metal conduit (LFMC) | 4.881 | 23 |
#4 THHN in other EMT sizes
Other wire sizes in 2-1/2" EMT
#12: 176#10: 111#8: 64#6: 46#4: 28#3: 24#2: 20#1: 15#1/0: 12#2/0: 10#3/0: 8#4/0: 7250 kcmil: 6300 kcmil: 5350 kcmil: 4500 kcmil: 3