5-inch Rigid Metal (RMC) Conduit Fill
Wire capacity of trade size 5 (metric designator 129) Rigid Metal Conduit (RMC), for THHN, XHHW, THW and RHW conductors from 14 AWG to 1000 kcmil.
5-inch Rigid Metal Conduit holds 98 × #4, 70 × #2, 43 × 1/0 AWG or 25 × 4/0 AWG THHN conductors at 40% fill. Internal area: 20.212 in²; usable at 40%: 8.085 in².
| Wire size | THHN | XHHW | THW | RHW | THHN in a nipple (60%) | THHN area (in²) |
|---|---|---|---|---|---|---|
| 14 AWG | 833 | 581 | 581 | 276 | 1250 | 0.0097 |
| 12 AWG | 608 | 446 | 446 | 229 | 912 | 0.0133 |
| 10 AWG | 383 | 332 | 332 | 185 | 574 | 0.0211 |
| 8 AWG | 221 | 185 | 185 | 97 | 331 | 0.0366 |
| 6 AWG | 159 | 137 | 111 | 77 | 239 | 0.0507 |
| 4 AWG | 98 | 99 | 83 | 60 | 147 | 0.0824 |
| 3 AWG | 83 | 84 | 71 | 53 | 124 | 0.0973 |
| 2 AWG | 70 | 70 | 60 | 46 | 104 | 0.1158 |
| 1 AWG | 51 | 52 | 42 | 30 | 77 | 0.1562 |
| 1/0 AWG | 43 | 44 | 36 | 26 | 65 | 0.1855 |
| 2/0 AWG | 36 | 37 | 31 | 23 | 54 | 0.2223 |
| 3/0 AWG | 30 | 30 | 26 | 20 | 45 | 0.2679 |
| 4/0 AWG | 25 | 25 | 21 | 17 | 37 | 0.3237 |
| 250 kcmil | 20 | 20 | 17 | 13 | 30 | 0.3970 |
| 300 kcmil | 17 | 18 | 15 | 11 | 26 | 0.4608 |
| 350 kcmil | 15 | 15 | 13 | 10 | 23 | 0.5242 |
| 400 kcmil | 13 | 14 | 12 | 9 | 20 | 0.5863 |
| 500 kcmil | 11 | 11 | 10 | 8 | 17 | 0.7073 |
| 600 kcmil | 9 | 9 | 8 | 6 | 14 | 0.8676 |
| 700 kcmil | 8 | 8 | 7 | 6 | 12 | 0.9887 |
| 750 kcmil | 7 | 7 | 7 | 5 | 11 | 1.0496 |
| 800 kcmil | 7 | 7 | 6 | 5 | 11 | 1.1085 |
| 900 kcmil | 6 | 6 | 6 | 5 | 10 | 1.2311 |
| 1000 kcmil | 6 | 6 | 5 | 4 | 9 | 1.3478 |
Mixed wire sizes? Calculate it
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5-inch conduit: Rigid Metal Conduit vs other types
Trade size is nominal. The real inside diameter, and so the wire count, changes with the wall thickness of each raceway type.
| Conduit type | ID (in) | Area (in²) | 40% (in²) | #12 THHN | #10 THHN | #6 THHN |
|---|---|---|---|---|---|---|
| PVC Schedule 40 | 5.016 | 19.761 | 7.904 | 594 | 374 | 156 |
| PVC Schedule 80 | 4.768 | 17.855 | 7.142 | 537 | 338 | 141 |
| Rigid Metal Conduit | 5.073 | 20.212 | 8.085 | 608 | 383 | 159 |
Other Rigid Metal Conduit sizes
Frequently asked questions
How many #12 wires fit in 5-inch Rigid Metal Conduit?
608 conductors of 12 AWG THHN/THWN-2 at the 40% fill limit. With thicker THW or XHHW insulation the count is 446.
What is the inside diameter and area of 5-inch Rigid Metal Conduit?
The internal diameter is 5.073 in. (128.9 mm) and the total cross-sectional area is 20.212 in². The usable area is 8.085 in² at 40% fill, 6.266 in² for two wires and 10.712 in² for one.
What is the largest wire I can pull three of in 5-inch Rigid Metal Conduit?
1000 kcmil THHN: 6 conductors fit at 40% fill. That is three current-carrying conductors with no ground; add the ground’s area and check again with the calculator if you need one.
Can I really load it with that many conductors?
For space, yes. But 608 current-carrying conductors in one raceway means heavy ampacity derating — 10 to 20 conductors are adjusted to 50% of their table ampacity. Fill tells you what fits; derating tells you what it can carry.
NECTables.com is an independent reference and is not affiliated with, endorsed by, or a substitute for the National Fire Protection Association (NFPA). NEC® and National Electrical Code® are registered trademarks of the NFPA. Values shown are commonly published engineering data and independent calculations based on the methods of NFPA 70; they are not a reproduction of the Code. Always confirm against the edition adopted in your jurisdiction, including local amendments, and consult a licensed electrician or engineer before doing electrical work.