How many #14 THHN fit in 3/4" PVC Sch 80?
1714 AWG THHN/THWN-2 wires in 3/4" Rigid PVC conduit, Schedule 80
0.409 sq in × 40 % = 0.1636 sq in allowed. ÷ 0.0097 sq in per wire = 16.87, which Note 7 rounds up to 17 because the decimal is 0.8 or more.
This pull in numbers
- 17 wires fill
- 40.3 % of 3/4" PVC Sch 80
- Limit for three or more
- 40 %
- For 18 or more
- 1" PVC Sch 80, up to 28
- Pipe to wire diameter
- 6.50 to 1
- In THW insulation
- 11 fit
- In XHHW-2 insulation
- 11 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 #14 THHN at 25 A in the 90 °C column becomes 12.5 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.
#14 THHN in other 3/4" conduit
| Conduit | Inside area | Most #14 THHN |
|---|---|---|
| Electrical metallic tubing | 0.533 | 22 |
| Intermediate metal conduit | 0.586 | 24 |
| Rigid metal conduit (RMC, GRC) | 0.549 | 22 |
| Rigid PVC conduit, Schedule 40 | 0.508 | 21 |
| Rigid PVC conduit, Schedule 80 | 0.409 | 17 |
| Flexible metal conduit (FMC, Greenfield) | 0.533 | 22 |
| Liquidtight flexible metal conduit (LFMC) | 0.541 | 22 |
| Electrical nonmetallic tubing (smurf tube) | 0.508 | 21 |