Cards on the table: I'm out of my depth right now, trying to work my way through this (using the "water in a pipe" analogy).
Often people with a welding machine at home connect into a 30 amp 220v clothes dryer outlet, even though their machine calls for a 50 amp circuit. The welding machine works- why does the machine call for 50 amps?
My guess: the machine works at the lower end of its capability because demand on the circuit is lower, but at the higher end (welding on thicker metal, for instance) it will overtax the circuit...? Heat up the wires?
Am I close?