How many #3 THHN fit in 1" Flex?
33 AWG THHN/THWN-2 wires in 1" Flexible metal conduit (FMC, Greenfield)
0.817 sq in × 40 % = 0.3268 sq in allowed. ÷ 0.0973 sq in per wire = 3.36, so 3.
This pull in numbers
- 3 wires fill
- 35.7 % of 1" Flex
- Limit for three or more
- 40 %
- For 4 or more
- 1-1/4" Flex, up to 5
- Pipe to wire diameter
- 2.90 to 1
- In THW insulation
- 3 fit
- In XHHW-2 insulation
- 3 fit
The pipe is 2.90 times the wire's diameter, inside the 2.8 to 3.2 range where three wires can wedge side by side on a pull. If you pull exactly three, go up a size or pull with care.
Before you pull 3
- The ground counts. Every wire in the pipe counts toward fill, the green or bare ground and the neutrals too. 3 is the total, not the hots.
- Bends. A full pipe pulls hard. Keep to 360° of bends between pull points, less for a tight fill.
#3 THHN in other 1" conduit
| Conduit | Inside area | Most #3 THHN |
|---|---|---|
| Electrical metallic tubing | 0.864 | 3 |
| Intermediate metal conduit | 0.959 | 4 |
| Rigid metal conduit (RMC, GRC) | 0.887 | 3 |
| Rigid PVC conduit, Schedule 40 | 0.832 | 3 |
| Rigid PVC conduit, Schedule 80 | 0.688 | 3 |
| Flexible metal conduit (FMC, Greenfield) | 0.817 | 3 |
| Liquidtight flexible metal conduit (LFMC) | 0.873 | 3 |
| Electrical nonmetallic tubing (smurf tube) | 0.832 | 3 |