How many #4 THHN fit in 4" PVC Sch 40?
614 AWG THHN/THWN-2 wires in 4" Rigid PVC conduit, Schedule 40
12.554 sq in × 40 % = 5.0216 sq in allowed. ÷ 0.0824 sq in per wire = 60.94, which Note 7 rounds up to 61 because the decimal is 0.8 or more.
This pull in numbers
- 61 wires fill
- 40.0 % of 4" PVC Sch 40
- Limit for three or more
- 40 %
- For 62 or more
- 5" PVC Sch 40, up to 96
- Pipe to wire diameter
- 12.34 to 1
- In THW insulation
- 51 fit
- In XHHW-2 insulation
- 61 fit
Before you pull 61
- The ground counts. Every wire in the pipe counts toward fill, the green or bare ground and the neutrals too. 61 is the total, not the hots.
- Derating. If all 61 were current-carrying, each would be adjusted to 35 % of its ampacity (Table 310.15(C)(1)): a #4 THHN at 95 A in the 90 °C column becomes 33.3 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.
#4 THHN in other 4" conduit
| Conduit | Inside area | Most #4 THHN |
|---|---|---|
| Electrical metallic tubing | 14.753 | 71 |
| Intermediate metal conduit | 13.631 | 66 |
| Rigid metal conduit (RMC, GRC) | 12.882 | 62 |
| Rigid PVC conduit, Schedule 40 | 12.554 | 61 |
| Rigid PVC conduit, Schedule 80 | 11.258 | 54 |
| Flexible metal conduit (FMC, Greenfield) | 12.566 | 61 |
| Liquidtight flexible metal conduit (LFMC) | 12.692 | 61 |
#4 THHN in other PVC Sch 40 sizes
Other wire sizes in 4" PVC Sch 40
#8: 137#6: 99#4: 61#3: 51#2: 43#1: 32#1/0: 27#2/0: 22#3/0: 18#4/0: 15250 kcmil: 12300 kcmil: 11350 kcmil: 9500 kcmil: 7