How Many 4/0 AWG Wires Fit in FMC Conduit?
Complete NEC-compliant fill chart for 4/0 AWG THHN wires in Flexible Metal Conduit (FMC) conduit. Maximum wire counts for all standard conduit sizes.
Quick Answer
For 4/0 AWG THHN wires in FMC conduit at 40% fill (3+ wires):
- • 1-1/4" FMC: 1 wires
- • 1-1/2" FMC: 2 wires
- • 2" FMC: 3 wires
4/0 AWG in FMC Conduit Fill Chart
| Conduit Size | Max Wires (40% Fill) | Fill % | Max Wires (Nipple 60%) | Fill % |
|---|---|---|---|---|
| 1-1/4" | 1 | 27% | 2 | 54% |
| 1-1/2" | 2 | 39% | 3 | 58% |
| 2" | 3 | 35% | 5 | 59% |
| 2-1/2" | 5 | 35% | 8 | 56% |
| 3" | 8 | 37% | 13 | 59% |
| 3-1/2" | 11 | 39% | 17 | 60% |
| 4" | 14 | 39% | 21 | 58% |
Understanding the Fill Chart
According to NEC (National Electrical Code) Chapter 9, Table 1, the maximum conduit fill percentage depends on the number of conductors:
- 1 conductor: 53% fill maximum
- 2 conductors: 31% fill maximum
- 3 or more conductors: 40% fill maximum
- Nipples (24" or less): 60% fill maximum
This chart shows the maximum number of 4/0 AWG THHN conductors that can fit in each FMC conduit size while maintaining NEC compliance.
Calculation Example
Question: How many 4/0 AWG THHN wires can fit in 1-1/2" FMC conduit?
Wire area: 0.3701 sq in per conductor
Conduit internal area: 1.901 sq in
Allowable fill (40%): 0.7604 sq in
Maximum wires: 0.7604 ÷ 0.3701 = 2 wires
Answer: You can fit up to 2 wires of 4/0 AWG THHN in 1-1/2" FMC conduit.