4" Flex conduit fill
4" Flexible metal conduit (FMC, Greenfield) has an inside area of 12.566 sq in (4.000 in across). Three or more wires may take 40 % of it: 5.0264 sq in.
- One wire, 53 %
- 6.6600 sq in
- Two wires, 31 %
- 3.8955 sq in
- Three or more, 40 %
- 5.0264 sq in
- Nipple, 60 %
- 7.5396 sq in
- Support
- Every 4.5 ft, 12 in from boxes
How many wires fit in 4" Flex
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 | 518 | 361 | 361 |
| 12 AWG | 378 | 277 | 277 |
| 10 AWG | 238 | 207 | 207 |
| 8 AWG | 137 | 115 | 115 |
| 6 AWG | 99 | 85 | 69 |
| 4 AWG | 61 | 61 | 51 |
| 3 AWG | 51 | 52 | 44 |
| 2 AWG | 43 | 44 | 37 |
| 1 AWG | 32 | 32 | 26 |
| 1/0 AWG | 27 | 27 | 22 |
| 2/0 AWG | 22 | 23 | 19 |
| 3/0 AWG | 18 | 19 | 16 |
| 4/0 AWG | 15 | 15 | 13 |
| 250 kcmil | 12 | 13 | 11 |
| 300 kcmil | 11 | 11 | 9 |
| 350 kcmil | 9 | 9 | 8 |
| 400 kcmil | 8 | 8 | 7 |
| 500 kcmil | 7 | 7 | 6 |
| 600 kcmil | 5 | 5 | 5 |
| 700 kcmil | 5 | 5 | 4 |
| 750 kcmil | 4 | 4 | 4 |
| 800 kcmil | 4 | 4 | 4 |
| 900 kcmil | 4 | 4 | 3 |
| 1000 kcmil | 3 | 3 | 3 |
Other 4" conduit
| Conduit | Inside area | #14 | #12 | #10 | #8 | #6 |
|---|---|---|---|---|---|---|
| Flexible metal conduit (FMC, Greenfield) | 12.566 | 518 | 378 | 238 | 137 | 99 |
| Electrical metallic tubing | 14.753 | 608 | 443 | 279 | 161 | 116 |
| Intermediate metal conduit | 13.631 | 562 | 410 | 258 | 149 | 107 |
| Rigid metal conduit (RMC, GRC) | 12.882 | 531 | 387 | 244 | 140 | 101 |
| Rigid PVC conduit, Schedule 40 | 12.554 | 517 | 377 | 238 | 137 | 99 |
| Rigid PVC conduit, Schedule 80 | 11.258 | 464 | 338 | 213 | 123 | 89 |
| Liquidtight flexible metal conduit (LFMC) | 12.692 | 523 | 381 | 240 | 138 | 100 |
About Flex
Flex is supported every 4-1/2 ft and within 12 in of each box (348.30). Short whips to equipment have their own exceptions. See strap spacing and the fill rules.