How many #4 THHN fit in 3/4" IMC?
34 AWG THHN/THWN-2 wires in 3/4" Intermediate metal conduit
0.586 sq in × 40 % = 0.2344 sq in allowed. ÷ 0.0824 sq in per wire = 2.84, which Note 7 rounds up to 3 because the decimal is 0.8 or more.
This pull in numbers
- 3 wires fill
- 42.2 % of 3/4" IMC
- Limit for three or more
- 40 %
- For 4 or more
- 1" IMC, up to 4
- Pipe to wire diameter
- 2.67 to 1
- In THW insulation
- 1 fit
- In XHHW-2 insulation
- 3 fit
Before you pull 3
- The ground counts. Every wire in the pipe counts toward fill, the green or bare ground and the neutrals too. 3 is the total, not the hots.
- Bends. A full pipe pulls hard. Keep to 360° of bends between pull points, less for a tight fill.
#4 THHN in other 3/4" conduit
| Conduit | Inside area | Most #4 THHN |
|---|---|---|
| Electrical metallic tubing | 0.533 | 2 |
| Intermediate metal conduit | 0.586 | 3 |
| Rigid metal conduit (RMC, GRC) | 0.549 | 2 |
| Rigid PVC conduit, Schedule 40 | 0.508 | 1 |
| Rigid PVC conduit, Schedule 80 | 0.409 | 1 |
| Flexible metal conduit (FMC, Greenfield) | 0.533 | 2 |
| Liquidtight flexible metal conduit (LFMC) | 0.541 | 2 |
| Electrical nonmetallic tubing (smurf tube) | 0.508 | 1 |