1" IMC conduit fill
1" Intermediate metal conduit has an inside area of 0.959 sq in (1.105 in across). Three or more wires may take 40 % of it: 0.3836 sq in.
- One wire, 53 %
- 0.5083 sq in
- Two wires, 31 %
- 0.2973 sq in
- Three or more, 40 %
- 0.3836 sq in
- Nipple, 60 %
- 0.5754 sq in
- Support
- Every 10 ft, 3 ft from boxes
- Sold in
- 10 ft sticks
How many wires fit in 1" IMC
All wires the same size and type, by Annex C's method. For a mix of sizes, open the calculator.
| Wire size | THHN/THWN-2 | XHHW-2 | THW/THW-2 |
|---|---|---|---|
| 14 AWG | 39 | 27 | 27 |
| 12 AWG | 29 | 21 | 21 |
| 10 AWG | 18 | 15 | 15 |
| 8 AWG | 10 | 8 | 8 |
| 6 AWG | 7 | 6 | 5 |
| 4 AWG | 4 | 4 | 4 |
| 3 AWG | 4 | 4 | 3 |
| 2 AWG | 3 | 3 | 3 |
| 1 AWG | 1 | 1 | 1 |
| 1/0 AWG | 1 | 1 | 1 |
| 2/0 AWG | 1 | 1 | 1 |
| 3/0 AWG | 1 | 1 | 1 |
| 4/0 AWG | 1 | 1 | 1 |
| 250 kcmil | 1 | 1 | 1 |
| 300 kcmil | 1 | 1 | 0 |
Other 1" conduit
| Conduit | Inside area | #14 | #12 | #10 | #8 | #6 |
|---|---|---|---|---|---|---|
| Intermediate metal conduit | 0.959 | 39 | 29 | 18 | 10 | 7 |
| Electrical metallic tubing | 0.864 | 35 | 26 | 16 | 9 | 7 |
| Rigid metal conduit (RMC, GRC) | 0.887 | 36 | 26 | 17 | 9 | 7 |
| Rigid PVC conduit, Schedule 40 | 0.832 | 34 | 25 | 15 | 9 | 6 |
| Rigid PVC conduit, Schedule 80 | 0.688 | 28 | 20 | 13 | 7 | 5 |
| Flexible metal conduit (FMC, Greenfield) | 0.817 | 33 | 24 | 15 | 9 | 6 |
| Liquidtight flexible metal conduit (LFMC) | 0.873 | 36 | 26 | 16 | 9 | 7 |
| Electrical nonmetallic tubing (smurf tube) | 0.832 | 34 | 25 | 15 | 9 | 6 |
About IMC
IMC has a thinner wall than rigid, so it has a little more room inside size for size. Support follows 342.30: within 3 ft of each box, then every 10 ft, or longer on straight runs with threaded couplings. See strap spacing and the fill rules.