3-inch PVC Schedule 40 Conduit Fill
Wire capacity of trade size 3 (metric designator 78) Rigid PVC Conduit, Schedule 40, for THHN, XHHW, THW and RHW conductors from 14 AWG to 1000 kcmil.
3-inch PVC Schedule 40 holds 79 × #8, 57 × #6, 35 × #4 or 25 × #2 THHN conductors at 40% fill. Internal area: 7.268 in²; usable at 40%: 2.907 in².
| Wire size | THHN | XHHW | THW | RHW | THHN in a nipple (60%) | THHN area (in²) |
|---|---|---|---|---|---|---|
| 14 AWG | 299 | 209 | 209 | 99 | 449 | 0.0097 |
| 12 AWG | 218 | 160 | 160 | 82 | 328 | 0.0133 |
| 10 AWG | 137 | 119 | 119 | 66 | 206 | 0.0211 |
| 8 AWG | 79 | 66 | 66 | 35 | 119 | 0.0366 |
| 6 AWG | 57 | 49 | 40 | 28 | 86 | 0.0507 |
| 4 AWG | 35 | 35 | 30 | 22 | 53 | 0.0824 |
| 3 AWG | 30 | 30 | 25 | 19 | 45 | 0.0973 |
| 2 AWG | 25 | 25 | 22 | 16 | 37 | 0.1158 |
| 1 AWG | 18 | 19 | 15 | 11 | 28 | 0.1562 |
| 1/0 AWG | 15 | 16 | 13 | 9 | 23 | 0.1855 |
| 2/0 AWG | 13 | 13 | 11 | 8 | 19 | 0.2223 |
| 3/0 AWG | 11 | 11 | 9 | 7 | 16 | 0.2679 |
| 4/0 AWG | 9 | 9 | 8 | 6 | 13 | 0.3237 |
| 250 kcmil | 7 | 7 | 6 | 4 | 11 | 0.3970 |
| 300 kcmil | 6 | 6 | 5 | 4 | 9 | 0.4608 |
| 350 kcmil | 5 | 5 | 5 | 3 | 8 | 0.5242 |
| 400 kcmil | 5 | 5 | 4 | 3 | 7 | 0.5863 |
| 500 kcmil | 4 | 4 | 3 | 3 | 6 | 0.7073 |
| 600 kcmil | 3 | 3 | 3 | 1 | 5 | 0.8676 |
| 700 kcmil | 3 | 3 | 2 | 1 | 4 | 0.9887 |
| 750 kcmil | 2 | 2 | 1 | 1 | 4 | 1.0496 |
| 800 kcmil | 2 | 2 | 1 | 1 | 4 | 1.1085 |
| 900 kcmil | 1 | 1 | 1 | 1 | 3 | 1.2311 |
| 1000 kcmil | 1 | 1 | 1 | 1 | 3 | 1.3478 |
Mixed wire sizes? Calculate it
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3-inch conduit: PVC Schedule 40 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 |
|---|---|---|---|---|---|---|
| EMT | 3.356 | 8.846 | 3.538 | 266 | 167 | 69 |
| PVC Schedule 40 | 3.042 | 7.268 | 2.907 | 218 | 137 | 57 |
| PVC Schedule 80 | 2.864 | 6.442 | 2.577 | 193 | 122 | 51 |
| Rigid Metal Conduit | 3.090 | 7.499 | 3.000 | 225 | 142 | 59 |
| IMC | 3.176 | 7.922 | 3.169 | 238 | 150 | 62 |
| Flexible Metal Conduit | 3.000 | 7.069 | 2.828 | 212 | 134 | 55 |
| Liquidtight Flexible Metal Conduit | 3.085 | 7.475 | 2.990 | 225 | 141 | 59 |
Other PVC Schedule 40 sizes
Frequently asked questions
How many #12 wires fit in 3-inch PVC Schedule 40?
218 conductors of 12 AWG THHN/THWN-2 at the 40% fill limit. With thicker THW or XHHW insulation the count is 160.
What is the inside diameter and area of 3-inch PVC Schedule 40?
The internal diameter is 3.042 in. (77.3 mm) and the total cross-sectional area is 7.268 in². The usable area is 2.907 in² at 40% fill, 2.253 in² for two wires and 3.852 in² for one.
What is the largest wire I can pull three of in 3-inch PVC Schedule 40?
700 kcmil THHN: 3 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 218 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.
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