How many 250 kcmil THHN fit in 5" PVC Sch 80?
18250 kcmil THHN/THWN-2 wires in 5" Rigid PVC conduit, Schedule 80
17.855 sq in × 40 % = 7.1420 sq in allowed. ÷ 0.3970 sq in per wire = 17.99, which Note 7 rounds up to 18 because the decimal is 0.8 or more.
This pull in numbers
- 18 wires fill
- 40.0 % of 5" PVC Sch 80
- Limit for three or more
- 40 %
- For 19 or more
- 6" PVC Sch 80, up to 25
- Pipe to wire diameter
- 6.71 to 1
- In THW insulation
- 15 fit
- In XHHW-2 insulation
- 18 fit
Before you pull 18
- The ground counts. Every wire in the pipe counts toward fill, the green or bare ground and the neutrals too. 18 is the total, not the hots.
- Derating. If all 18 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 80 sizes
Other wire sizes in 5" PVC Sch 80
#8: 195#6: 141#4: 86#3: 73#2: 61#1: 45#1/0: 38#2/0: 32#3/0: 26#4/0: 22250 kcmil: 18300 kcmil: 15350 kcmil: 13500 kcmil: 10