How many #6 THHN fit in 1-1/2" IMC?
176 AWG THHN/THWN-2 wires in 1-1/2" Intermediate metal conduit
2.225 sq in × 40 % = 0.8900 sq in allowed. ÷ 0.0507 sq in per wire = 17.55, so 17.
This pull in numbers
- 17 wires fill
- 38.7 % of 1-1/2" IMC
- Limit for three or more
- 40 %
- For 18 or more
- 2" IMC, up to 28
- Pipe to wire diameter
- 6.63 to 1
- In THW insulation
- 12 fit
- In XHHW-2 insulation
- 15 fit
Before you pull 17
- The ground counts. Every wire in the pipe counts toward fill, the green or bare ground and the neutrals too. 17 is the total, not the hots.
- Derating. If all 17 were current-carrying, each would be adjusted to 50 % of its ampacity (Table 310.15(C)(1)): a #6 THHN at 75 A in the 90 °C column becomes 37.5 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.
#6 THHN in other 1-1/2" conduit
| Conduit | Inside area | Most #6 THHN |
|---|---|---|
| Electrical metallic tubing | 2.036 | 16 |
| Intermediate metal conduit | 2.225 | 17 |
| Rigid metal conduit (RMC, GRC) | 2.071 | 16 |
| Rigid PVC conduit, Schedule 40 | 1.986 | 15 |
| Rigid PVC conduit, Schedule 80 | 1.711 | 13 |
| Flexible metal conduit (FMC, Greenfield) | 1.858 | 14 |
| Liquidtight flexible metal conduit (LFMC) | 1.981 | 15 |
| Electrical nonmetallic tubing (smurf tube) | 1.986 | 15 |
#6 THHN in other IMC sizes
Other wire sizes in 1-1/2" IMC
#14: 91#12: 67#10: 42#8: 24#6: 17#4: 11#3: 9#2: 7#1: 5#1/0: 4#2/0: 4#3/0: 3#4/0: 2250 kcmil: 1300 kcmil: 1350 kcmil: 1500 kcmil: 1