It’s power for a 480 3ø garbage disposal that some how the wiring compartment rotted out, and allowed all this crap to flow into the box. The customer said with a chuckle, “Could ya clean that up a bit before the new one comes.”
I'm not sure what kind of battery acid they used to clean stuff with... But rotted through the disposal, flowed inside the flex into the box and down the wall. Eating everything in its path. This section of wall is coming out.
I was actually really surprised it had not shorted yet, and still worked! A lot of the insulation was eaten off.
(Before anyone gets worried... it's a wye system, and the ground and neutral are good.)
Mark Heller "Well - I oughta....." -Jackie Gleason