NEC 2023
Chapter 9, Table 1 — Conduit Fill Percentages
Maximum percent of cross-sectional area of conduit or tubing that may be filled with conductors. Applies to all raceway types (EMT, PVC, RMC, IMC, etc.).
| Number of Conductors | Max Fill % | Notes |
|---|---|---|
| 1 | 53% | 1 conductor — 53% maximum fill |
| 2 | 31% | 2 conductors — 31% maximum fill |
| 3+ | 40% | 3 or more conductors — 40% maximum fill |
How to Apply This Table
- Count the number of current-carrying conductors (not including equipment grounding conductors) to determine the fill percentage limit.
- Sum the cross-sectional areas (in²) of all conductors from NEC Chapter 9, Table 5 (THHN/THWN conductor areas).
- Divide the total conductor area by the interior cross-sectional area of the conduit (from NEC Chapter 9, Table 4).
- Confirm the resulting percentage is at or below the limit from Table 1 above.
Reference: NEC 2023 Chapter 9, Table 1. Equipment grounding conductors (EGC) are counted in fill calculations but do not affect the selection of fill percentage. Conduit nipples ≤ 24″ may be filled to 60% per NEC 300.17.