Posted by Sherman in Idaho [72.47.153.28] on Sunday, June 22, 2014 at 09:52:34 :
In Reply to: Welding/Electrical posted by Mike Hernke (MO) [69.179.162.43] on Sunday, June 22, 2014 at 09:06:34 :
Measure at the power plug. A welder is basically a constant-current power supply. It attempts to provide a given number of AMPS, not VOLTS, to the arc. During welding, the voltage at the rods will jump all over the place, even if everything's working perfectly.
Remember the amp ratings of a branch circuit are based on safety, not voltage drop. A 30 amp breaker will protect any length of #10 wire from overheating and catching fire, but if the wire is too long, the voltage at the far end of it will have dropped too low to be useful.