What Size Wire for a Generator Inlet?
Wire and breaker sizing for a Generator Inlet — the typical 240V circuit, plus the code details (NEC 310.16) that change the answer.
Calculations are built on the 2023 National Electrical Code (NEC) and cross-checked against the published code tables. How we verify. Last reviewed June 2026.
On a 50A 240V circuit at 75°C terminations. 60°C terminations: 6.
Protected by a 50A breaker (NEC 240.6).
Generator Inlet current varies by model. The size above is the common case — always size the conductor to the unit’s nameplate rating and protect it at the labeled maximum breaker/fuse.
Generator Inlet Circuit Details
- Size the inlet conductors to the generator output and the inlet/breaker rating — a 50A inlet uses 8 AWG copper minimum (6 AWG for longer runs).
- Pair the inlet with an interlock or transfer switch so utility and generator can never backfeed.
- A 30A inlet (10 AWG) suits smaller portable generators.
Long run to your generator inlet?
Over distance, voltage drop can require a larger wire than the table above. See the 50A wire size by distance:
Size it for your exact install
Open the calculator pre-filled with 50A at 240V to add distance, material and temperature.