The size of a welding machine is given by current. 150-200 amps for light duty; 250-300 amps for manufacturing; 400-600 amps for construction.
The higher a welding machine's voltage, the more power output it will have at a given current:
Potential (volts) x Current (amps) = Power (watts)
Most households have 230 volts, single phase. A welding machine will run off of either single or three phase power. Converting phases is very inefficient.
Constant current (CC) machines are used for SMAW and GTAW processes. They can run off of AC, DC, or either, depending on the machine. CC machines keep current constant, even when voltage changes.
Constant voltage (CV) machines (aka constant potential) are used for all wire-feed welding processes, including GMAW and FCAW. They hold a narrow voltage range despite changes in arc length and amperage. CC/CV machines provide the most versatility and can be used with any arc-welding process.
