Selenium rectifiers in Zenith radios

[Electronic M]

House fuses and breakers don't always catch failures. When I was a kid I had a 60's GE TOASTER-oven (looked more like a toaster) with the original rubber cord. I had put it out of use because the house wiring would hum when it was on, but one morning I had to make my own food as we were in a rush to pick up Dad from the airport and I dragged it out to make my food. Well it hummed the whole time it was on, finished it's cooking cycle, and a moment later...POW the insulation between the leads at the plug failed, and it let out a bunch of smoke and a pinky red flame from the plug after a moment of surprise I grabbed the cord away from the plug and gave it a good yank which managed to unplug it. The aftermath: a good 1/4" of one of the cord wires starting at the plug moving towards the toaster was vaporized, and the outlet and plate that I had changed months earlier was charred and had to be replaced. The fuse never blew!

In my next house before I knew my way around a DMM I tried to find which two leads on a 4 pin connector for a portable set were 120V by looking for 120V with a DMM...Well I had the test leads in the 10A current measurement position which is a dead short between the leads...I put the test leads in the pin holes in the plugged in cord, and knew I had found 120V when smoke came billowing out of those holes...The breaker did not trip then either.