How Many 1 AWG Wires Fit in IMC Conduit?
Complete NEC-compliant fill chart for 1 AWG THHN wires in Intermediate Metal Conduit (IMC) conduit. Maximum wire counts for all standard conduit sizes.
Quick Answer
For 1 AWG THHN wires in IMC conduit at 40% fill (3+ wires):
- • 3/4" IMC: 1 wires
- • 1" IMC: 2 wires
- • 1-1/4" IMC: 4 wires
1 AWG in IMC Conduit Fill Chart
| Conduit Size | Max Wires (40% Fill) | Fill % | Max Wires (Nipple 60%) | Fill % |
|---|---|---|---|---|
| 3/4" | 1 | 27% | 2 | 53% |
| 1" | 2 | 33% | 3 | 49% |
| 1-1/4" | 4 | 38% | 6 | 57% |
| 1-1/2" | 5 | 35% | 8 | 56% |
| 2" | 9 | 38% | 14 | 60% |
| 2-1/2" | 16 | 39% | 24 | 59% |
| 3" | 24 | 39% | 37 | 60% |
| 3-1/2" | 32 | 40% | 48 | 60% |
| 4" | 40 | 39% | 61 | 60% |
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 1 AWG THHN conductors that can fit in each IMC conduit size while maintaining NEC compliance.
Calculation Example
Question: How many 1 AWG THHN wires can fit in 1" IMC conduit?
Wire area: 0.1562 sq in per conductor
Conduit internal area: 0.959 sq in
Allowable fill (40%): 0.3836 sq in
Maximum wires: 0.3836 ÷ 0.1562 = 2 wires
Answer: You can fit up to 2 wires of 1 AWG THHN in 1" IMC conduit.