Okay, White, I feel you. I feel your pain. I'm white too.

Here's a specific question. If I'm cutting foam on my hot wire cutter using 5 volts AC (and 3 amps) that's coming out of my 12 volt transformer which is controlled by a 120 volt variac set at 50 volts AC output, what exactly makes that different or safer than controlling my voltage with a variac alone set at 5 volts?

I guess the physical separation of the primary and the secondary doesn't mean there won't be some big amp load if somebody inadvertently contacts the cutting wire.

They say to use a transformer after the variac because it's safer than going off the variac's single wire toroid style transformer for some reason. I believe I can change the size of the fuse in the variac to a smaller amperage rating, so I wonder what it is that makes it safer to run the 2nd transformer after the variac.

And White, read this: "...magnignetic fields cause impeadance..." Where did you learn that? Be nice.

Thanks.