Shocking Surprise

Exposed to water, im guessing.
GFCI shouldn't allow that.
Very true

LOL I REALLY got my a $$ handed to me by a GFCI. This was a house under construction, fed by nothing but 2 or 3 extension cords off a temp power pole all fed from GFCI

When I was in HVAC/R there was a constant struggle between the owner and contractors. The contractors often wanted the furnace going to provide heat and we (rightfully) did NOT because of construction dirt and debri getting into the furnace. The contractors would threaten to not hire us "next time" and so that is the push/ pull

So this was a big house, awful, dark, near dusk, cold wet winter day, the site was muddy, snowy, a mess. I'm working in poor light down at the furnace, cold, getting dark, running out of time. Wanting to get it fired. It's LPG, out of town, and the temp power pole.

So I'm trying to even determine if there's a circuit live, that I can use. I had a little LED tester that only drew a few milliamps to operate, but it turns out it was enough to trip a GFCI. I was arguing with this, and checked with the tester on a wire, and stabbed the other probe to the furnace case. "CLICK" no lights. WTF?? (GFCI was fairly new back then, and I did not realize what happened

So I wade through the mud and snow out to the power pole hundreds of feet away, to find that the GFCI had tripped. AND THEN SOMEHOW MANAGED TO DO THAT AGAIN. So ANOTHER LONG ROUND TRIP to the pole and back!!!

By the way, if a furnace ate a blower in the first couple years, and showed signs of sheet rock dust, we sent the bill to the building contractor!!!