This bit of advice may help very few people, due to the rarity of the circumstance(s), but I'm sharing it because it was a
close call for me, and except for the fact that I was wearing eyeglasses, I could have been quite seriously injured or even
blinded.
I was doing some electrical work on 208V single phase wiring for a shop, and wanted to test continuity of a circuit. But I
didn't have a voltmeter. I did have various wires, and a utility light (sometimes called a "drop light") that included a regular
"household" lightbulb. I knew that 208V would destroy the filament of the bulb, but seeing the flash as this happened would
confirm for me continuity. And a lightbulb like that isn't expensive. Well, as soon as I turned it on, the entire lightbulb
exploded violently, launching shards at me (including my face). Apparently this voltage not only melted the filament but
vaporized it to the extent of generating sufficient pressure to shatter the glass bulb. I suggest people never do anything
similar to this (i.e., using a 12V bulb to test continuity of 115V circuitry).