Originally Posted by Oldguy48
Back to the original question, how about a Ford type starter solenoid, controlled by a normally open foot switch, or even a push button. Power it from a battery charger or a car battery, and connect the solenoid in the ground lead circuit. No modifications to the welder, and easy to hook up.
Now that's a good idea! I also thought about an emergency stop buttom from some kind of industrial machine that you could just press with your foot, but it would have capable of carrying probably at least 30 amps or more.