3" Rigid conduit fill
3" Rigid metal conduit (RMC, GRC) has an inside area of 7.499 sq in (3.090 in across). Three or more wires may take 40 % of it: 2.9996 sq in.
- One wire, 53 %
- 3.9745 sq in
- Two wires, 31 %
- 2.3247 sq in
- Three or more, 40 %
- 2.9996 sq in
- Nipple, 60 %
- 4.4994 sq in
- Support
- Every 10 ft, 3 ft from boxes
- Sold in
- 10 ft sticks
How many wires fit in 3" Rigid
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 | 309 | 215 | 215 |
| 12 AWG | 225 | 165 | 165 |
| 10 AWG | 142 | 123 | 123 |
| 8 AWG | 82 | 68 | 68 |
| 6 AWG | 59 | 51 | 41 |
| 4 AWG | 36 | 37 | 31 |
| 3 AWG | 31 | 31 | 26 |
| 2 AWG | 26 | 26 | 22 |
| 1 AWG | 19 | 19 | 15 |
| 1/0 AWG | 16 | 16 | 13 |
| 2/0 AWG | 13 | 13 | 11 |
| 3/0 AWG | 11 | 11 | 9 |
| 4/0 AWG | 9 | 9 | 8 |
| 250 kcmil | 7 | 7 | 6 |
| 300 kcmil | 6 | 6 | 5 |
| 350 kcmil | 5 | 6 | 5 |
| 400 kcmil | 5 | 5 | 4 |
| 500 kcmil | 4 | 4 | 3 |
| 600 kcmil | 3 | 3 | 3 |
| 700 kcmil | 3 | 3 | 2 |
| 750 kcmil | 3 | 3 | 1 |
| 800 kcmil | 2 | 2 | 1 |
| 900 kcmil | 1 | 1 | 1 |
| 1000 kcmil | 1 | 1 | 1 |
Other 3" conduit
| Conduit | Inside area | #14 | #12 | #10 | #8 | #6 |
|---|---|---|---|---|---|---|
| Rigid metal conduit (RMC, GRC) | 7.499 | 309 | 225 | 142 | 82 | 59 |
| Electrical metallic tubing | 8.846 | 364 | 266 | 167 | 96 | 69 |
| Intermediate metal conduit | 7.922 | 326 | 238 | 150 | 86 | 62 |
| Rigid PVC conduit, Schedule 40 | 7.268 | 299 | 218 | 137 | 79 | 57 |
| Rigid PVC conduit, Schedule 80 | 6.442 | 265 | 193 | 122 | 70 | 51 |
| Flexible metal conduit (FMC, Greenfield) | 7.069 | 291 | 212 | 134 | 77 | 55 |
| Liquidtight flexible metal conduit (LFMC) | 7.475 | 308 | 225 | 141 | 81 | 59 |
About Rigid
Rigid (galvanized rigid conduit, GRC) has the thickest wall and the least room inside of the steel types. Support follows 344.30: within 3 ft of each box, then every 10 ft, or longer on straight runs with threaded couplings (Table 344.30(B)(2)). See strap spacing and the fill rules.