How many 350 kcmil THHN fit in 6" PVC Sch 40?
21350 kcmil THHN/THWN-2 wires in 6" Rigid PVC conduit, Schedule 40
28.567 sq in × 40 % = 11.4268 sq in allowed. ÷ 0.5242 sq in per wire = 21.80, so 21.
This pull in numbers
- 21 wires fill
- 38.5 % of 6" PVC Sch 40
- Limit for three or more
- 40 %
- For 22 or more
- no bigger PVC Sch 40
- Pipe to wire diameter
- 7.38 to 1
- In THW insulation
- 19 fit
- In XHHW-2 insulation
- 22 fit
Before you pull 21
- The ground counts. Every wire in the pipe counts toward fill, the green or bare ground and the neutrals too. 21 is the total, not the hots.
- Derating. If all 21 were current-carrying, each would be adjusted to 45 % of its ampacity (Table 310.15(C)(1)): a 350 kcmil THHN at 350 A in the 90 °C column becomes 157.5 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.
350 kcmil THHN in other 6" conduit
| Conduit | Inside area | Most 350 kcmil THHN |
|---|---|---|
| Rigid metal conduit (RMC, GRC) | 29.158 | 22 |
| Rigid PVC conduit, Schedule 40 | 28.567 | 21 |
| Rigid PVC conduit, Schedule 80 | 25.598 | 19 |
350 kcmil THHN in other PVC Sch 40 sizes
Other wire sizes in 6" PVC Sch 40
#4: 138#3: 117#2: 98#1: 73#1/0: 61#2/0: 51#3/0: 42#4/0: 35250 kcmil: 28300 kcmil: 24350 kcmil: 21500 kcmil: 16