Speaking of arc welder. I remember a guy telling me back in the 90s a few of the amplifier companies used to do just that. To show their amps were stable into fractional ohms (at over 1kW) they would actually use them as arc welders.
About 1980 I met a guy, the late Brian Gary Wachner, founder of the BGW company (that still exists).
He built very powerful amplifiers, and one was called "the Arc Welder Special".
I saw a demo at some exhibition where they demonstrated their efficient protection circuit by creating big sparks when shorting the output terminals.
The year after my company demonstrated our new amplifiers driving an electric drill with a 50 Hz signal at the input... just to do something different.
In those years I had a second job: in my home lab I did maintenance and repairs for many importers of pro-audio gear, and I must admit that I've seen only one BGW amplifier, and many more of better known manufacturers..