Here is my setup:
I have a 120V 20A welder that I am fairly certain uses a transformer to drop the voltage which increases the amperage. I have a 120V 20A variac that I want to put in series on the secondary side of that transformer.
Is it safe to push more current through the variac because it's at lower voltage? I believe it should be safe as long as the wattage is the same. The variac is rated for 2000VA (which is the same as Watts).
I know the other way around, higher voltage at lower amperage is NOT necessarily safe. I know components are rated in both WATTS and VOLTAGE, because if you push the volts too high, eventually the resistance of the air between the wires will be lower than the resistance of the circuit and it will arc (short-circuit).
So is higher current at lower voltage safe if the watts are the same?