How many 250 kcmil THHN fit in 5" PVC Sch 40?
20250 kcmil THHN/THWN-2 wires in 5" Rigid PVC conduit, Schedule 40
19.761 sq in × 40 % = 7.9044 sq in allowed. ÷ 0.3970 sq in per wire = 19.91, which Note 7 rounds up to 20 because the decimal is 0.8 or more.
This pull in numbers
- 20 wires fill
- 40.2 % of 5" PVC Sch 40
- Limit for three or more
- 40 %
- For 21 or more
- 6" PVC Sch 40, up to 28
- Pipe to wire diameter
- 7.05 to 1
- In THW insulation
- 17 fit
- In XHHW-2 insulation
- 20 fit
Before you pull 20
- The ground counts. Every wire in the pipe counts toward fill, the green or bare ground and the neutrals too. 20 is the total, not the hots.
- Derating. If all 20 were current-carrying, each would be adjusted to 50 % of its ampacity (Table 310.15(C)(1)): a 250 kcmil THHN at 290 A in the 90 °C column becomes 145 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.
250 kcmil THHN in other 5" conduit
| Conduit | Inside area | Most 250 kcmil THHN |
|---|---|---|
| Rigid metal conduit (RMC, GRC) | 20.212 | 20 |
| Rigid PVC conduit, Schedule 40 | 19.761 | 20 |
| Rigid PVC conduit, Schedule 80 | 17.855 | 18 |
250 kcmil THHN in other PVC Sch 40 sizes
Other wire sizes in 5" PVC Sch 40
#6: 156#4: 96#3: 81#2: 68#1: 50#1/0: 42#2/0: 35#3/0: 29#4/0: 24250 kcmil: 20300 kcmil: 17350 kcmil: 15500 kcmil: 11