250 kcmil Conduit Fill — Wires per Conduit Size
How many 250 kcmil THHN conductors fit in EMT, IMC, RMC and PVC conduit, from 1/2 inch through 4 inch, with the 40% fill rule applied.
Quick answer
No 250 kcmil THHN conductors fit in 1/2 inch EMT and 0 fit in 3/4 inch EMT, at 40% fill for three or more conductors. Each conductor consumes 0.3970 sq in from a nominal insulated outside diameter of 0.711 in. Neutrals and grounds count.
250 kcmil conductors per conduit trade size
Same-size conductors only, at 53% for one, 31% for two and 40% for three or more.
| Conduit | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" | 2-1/2" | 3" | 3-1/2" | 4" |
|---|---|---|---|---|---|---|---|---|---|---|
| EMT | — | — | 1 | 1 | 1 | 3 | 5 | 8 | 11 | 14 |
| IMC | — | — | 1 | 1 | 1 | 3 | 5 | 7 | 10 | 13 |
| RMC | — | — | 1 | 1 | 1 | 3 | 4 | 7 | 10 | 12 |
| PVC Sch 40 | — | — | 1 | 1 | 1 | 3 | 4 | 7 | 9 | 12 |
| PVC Sch 80 | — | — | — | 1 | 1 | 2 | 4 | 6 | 8 | 11 |
Published standard — source: Raceway internal areas from product standards (EMT, IMC, RMC, PVC Sch 40, PVC Sch 80); conductor OD from nominal THHN dimensions
Source & method: Counts are the largest whole number where n × conductor area stays inside the raceway area times the applicable fill percentage. Mix conductor sizes in the calculator.
What each raceway type means
- EMT — EMT (electrical metallic tubing)
- IMC — IMC (intermediate metal conduit)
- RMC — RMC (rigid metal conduit)
- PVC Sch 40 — PVC Schedule 40
- PVC Sch 80 — PVC Schedule 80
Frequently asked
- How many 250 kcmil wires fit in 1/2 inch EMT?
- None — this size does not fit 1/2 inch EMT; step up a trade size.
- How many 250 kcmil wires fit in 3/4 inch EMT?
- 0 conductors, using a nominal THHN outside diameter of 0.711 in and the 40% fill rule for three or more conductors.
- Do neutrals and grounds count toward fill?
- Yes, every conductor in the raceway counts for fill. Grounds are excluded only from the count of current-carrying conductors used for ampacity adjustment.
- What is the cross-sectional area of 250 kcmil THHN?
- About 0.3970 square inches, from A = π × (OD / 2)² with a nominal insulated OD of 0.711 in.
More on 250 kcmil
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