What Size Wire for a Welder?
Wire and breaker sizing for a Welder — the typical 240V circuit, plus the code details (NEC Article 630) 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).
Welder 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.
Welder Circuit Details
- NEC 630 lets welder circuits be sized on the duty cycle, not just the rated input — small MIG/TIG units often run on 30A (10 AWG), larger stick/plasma on 50A (8 AWG copper minimum, 6 AWG common).
- Use the input current and duty cycle on the data plate.
- A NEMA 6-50 receptacle is common for 50A welders.
Long run to your welder?
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.