How many #12 THHN fit in 3/8" Liquidtight?
512 AWG THHN/THWN-2 wires in 3/8" Liquidtight flexible metal conduit (LFMC)
0.192 sq in × 40 % = 0.0768 sq in allowed. ÷ 0.0133 sq in per wire = 5.77, so 5.
This pull in numbers
- 5 wires fill
- 34.6 % of 3/8" Liquidtight
- Limit for three or more
- 40 %
- For 6 or more
- 1/2" Liquidtight, up to 9
- Pipe to wire diameter
- 3.80 to 1
- In THW insulation
- 4 fit
- In XHHW-2 insulation
- 4 fit
Before you pull 5
- The ground counts. Every wire in the pipe counts toward fill, the green or bare ground and the neutrals too. 5 is the total, not the hots.
- Derating. If all 5 were current-carrying, each would be adjusted to 80 % of its ampacity (Table 310.15(C)(1)): a #12 THHN at 30 A in the 90 °C column becomes 24 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.
#12 THHN in other 3/8" conduit
| Conduit | Inside area | Most #12 THHN |
|---|---|---|
| Flexible metal conduit (FMC, Greenfield) | 0.116 | 3 |
| Liquidtight flexible metal conduit (LFMC) | 0.192 | 5 |