How many #4 THHN fit in 2" Flex?
164 AWG THHN/THWN-2 wires in 2" Flexible metal conduit (FMC, Greenfield)
3.269 sq in × 40 % = 1.3076 sq in allowed. ÷ 0.0824 sq in per wire = 15.87, which Note 7 rounds up to 16 because the decimal is 0.8 or more.
This pull in numbers
- 16 wires fill
- 40.3 % of 2" Flex
- Limit for three or more
- 40 %
- For 17 or more
- 2-1/2" Flex, up to 24
- Pipe to wire diameter
- 6.30 to 1
- In THW insulation
- 13 fit
- In XHHW-2 insulation
- 16 fit
Before you pull 16
- The ground counts. Every wire in the pipe counts toward fill, the green or bare ground and the neutrals too. 16 is the total, not the hots.
- Derating. If all 16 were current-carrying, each would be adjusted to 50 % of its ampacity (Table 310.15(C)(1)): a #4 THHN at 95 A in the 90 °C column becomes 47.5 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.
#4 THHN in other 2" conduit
| Conduit | Inside area | Most #4 THHN |
|---|---|---|
| Electrical metallic tubing | 3.356 | 16 |
| Intermediate metal conduit | 3.630 | 17 |
| Rigid metal conduit (RMC, GRC) | 3.408 | 16 |
| Rigid PVC conduit, Schedule 40 | 3.291 | 16 |
| Rigid PVC conduit, Schedule 80 | 2.874 | 14 |
| Flexible metal conduit (FMC, Greenfield) | 3.269 | 16 |
| Liquidtight flexible metal conduit (LFMC) | 3.246 | 15 |
| Electrical nonmetallic tubing (smurf tube) | 3.291 | 16 |
#4 THHN in other Flex sizes
Other wire sizes in 2" Flex
#14: 135#12: 98#10: 62#8: 35#6: 25#4: 16#3: 13#2: 11#1: 8#1/0: 7#2/0: 6#3/0: 5#4/0: 4250 kcmil: 3300 kcmil: 3350 kcmil: 1500 kcmil: 1