4 AWG Conduit Fill — Wires per Conduit Size
How many 4 AWG 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
1 4 AWG THHN conductors fit in 1/2 inch EMT and 2 fit in 3/4 inch EMT, at 40% fill for three or more conductors. Each conductor consumes 0.0824 sq in from a nominal insulated outside diameter of 0.324 in. Neutrals and grounds count.
4 AWG 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 | 2 | 4 | 7 | 9 | 16 | 28 | 42 | 56 | 71 |
| IMC | 1 | 2 | 4 | 7 | 10 | 17 | 24 | 38 | 51 | 66 |
| RMC | 1 | 2 | 4 | 7 | 10 | 16 | 23 | 36 | 48 | 62 |
| PVC Sch 40 | 1 | 1 | 4 | 7 | 9 | 15 | 22 | 35 | 47 | 60 |
| PVC Sch 80 | 1 | 1 | 3 | 6 | 8 | 13 | 19 | 31 | 42 | 54 |
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 4 AWG wires fit in 1/2 inch EMT?
- 1 4 AWG THHN conductors fit in 1/2 inch EMT at the applicable fill percentage.
- How many 4 AWG wires fit in 3/4 inch EMT?
- 2 conductors, using a nominal THHN outside diameter of 0.324 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 4 AWG THHN?
- About 0.0824 square inches, from A = π × (OD / 2)² with a nominal insulated OD of 0.324 in.
More on 4 AWG
Related charts & calculators
- Voltage Drop CalculatorPercent drop, end voltage and minimum conductor for any run length.
- Conduit Fill CalculatorFill percentage and maximum conductor count for EMT, RMC, IMC and PVC.
- Breaker Size CalculatorOvercurrent device rating and minimum conductor from load current.
- Wire Ampacity CalculatorDerated ampacity for ambient temperature and bundled conductors.
- Box Fill CalculatorVolume allowances for conductors, clamps, devices and grounds per NEC 314.16.
- Ampacity ChartEstimated allowable ampacity by conductor size, material and insulation rating.