3" Flex conduit fill
3" Flexible metal conduit (FMC, Greenfield) has an inside area of 7.069 sq in (3.000 in across). Three or more wires may take 40 % of it: 2.8276 sq in.
- One wire, 53 %
- 3.7466 sq in
- Two wires, 31 %
- 2.1914 sq in
- Three or more, 40 %
- 2.8276 sq in
- Nipple, 60 %
- 4.2414 sq in
- Support
- Every 4.5 ft, 12 in from boxes
How many wires fit in 3" 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 | 291 | 203 | 203 |
| 12 AWG | 212 | 156 | 156 |
| 10 AWG | 134 | 116 | 116 |
| 8 AWG | 77 | 64 | 64 |
| 6 AWG | 55 | 48 | 39 |
| 4 AWG | 34 | 34 | 29 |
| 3 AWG | 29 | 29 | 25 |
| 2 AWG | 24 | 24 | 21 |
| 1 AWG | 18 | 18 | 15 |
| 1/0 AWG | 15 | 15 | 12 |
| 2/0 AWG | 12 | 13 | 10 |
| 3/0 AWG | 10 | 10 | 9 |
| 4/0 AWG | 8 | 9 | 7 |
| 250 kcmil | 7 | 7 | 6 |
| 300 kcmil | 6 | 6 | 5 |
| 350 kcmil | 5 | 5 | 4 |
| 400 kcmil | 5 | 5 | 4 |
| 500 kcmil | 4 | 4 | 3 |
| 600 kcmil | 3 | 3 | 3 |
| 700 kcmil | 3 | 3 | 1 |
| 750 kcmil | 2 | 2 | 1 |
| 800 kcmil | 1 | 1 | 1 |
| 900 kcmil | 1 | 1 | 1 |
| 1000 kcmil | 1 | 1 | 1 |
Other 3" conduit
| Conduit | Inside area | #14 | #12 | #10 | #8 | #6 |
|---|---|---|---|---|---|---|
| Flexible metal conduit (FMC, Greenfield) | 7.069 | 291 | 212 | 134 | 77 | 55 |
| Electrical metallic tubing | 8.846 | 364 | 266 | 167 | 96 | 69 |
| Intermediate metal conduit | 7.922 | 326 | 238 | 150 | 86 | 62 |
| Rigid metal conduit (RMC, GRC) | 7.499 | 309 | 225 | 142 | 82 | 59 |
| Rigid PVC conduit, Schedule 40 | 7.268 | 299 | 218 | 137 | 79 | 57 |
| Rigid PVC conduit, Schedule 80 | 6.442 | 265 | 193 | 122 | 70 | 51 |
| Liquidtight flexible metal conduit (LFMC) | 7.475 | 308 | 225 | 141 | 81 | 59 |
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.