A typical 240V welder (up to 250A output) draws about 40-50 amps from the wall. Smaller 120V welders can use a standard 20A outlet.
| Recommended wire | 6/2 with ground |
| Breaker | 50A double-pole |
| Voltage | 240V |
| Typical amperage | 40A |
| Circuit amperage | 50A |
| NEC reference | NEC 630 |
| Max recommended distance | About 185 feet one-way for 3% drop at 40A |
Welders have a duty cycle rating. A welder rated at 200A/30% duty cycle draws maximum current only 30% of the time, which affects the NEC wire sizing calculation.
Wire size depends on the welder's input current. A full-size 250A MIG or stick welder drawing 40–50A needs 6 AWG copper on a 50A, 240V double-pole breaker. A 140A welder drawing 27–30A uses 8 AWG copper on a 40A breaker. Check the nameplate for exact amperage.
Welder circuits can use a breaker rated at 200% of the welder's rated input current per NEC 630.12 (welders have intermittent duty cycles). A welder drawing 30A at 240V can use up to a 60A breaker. Most homeowners use a 50A circuit for flexibility.
Small 120V welders (up to 140A output, 20A input) can use a standard 20A outlet on a 12 AWG circuit. For best performance, use a dedicated 20A circuit rather than sharing with other appliances. 120V welders are limited to thinner materials (under 3/16 inch).
For 240V welders, a dedicated circuit is strongly recommended and often required by NEC. Welders draw heavy current during the weld cycle, which can trip breakers or dim lights if shared. A dedicated 50A circuit with 6 AWG copper wire is standard for a shop welder.