I don't know whenever my input counts, but...
When using Intel 486DX4-100, with rather noname 200W AT PSU, I came across an older hard drive, which I've plugged in and pressed the "power" (AT supplies had mechanical power switch). As it turned around, hard drive had a short, so excess current went into cable, it got hot, but then protection turned on and psu switched off, but since it was mechanical power on, after shutdown, psu restarted, again catching a short and starting to melt the cable, all this happened in loop, for about 5 seconds, until I understood what was happening and unplugged the PSU. IDE cable was totally fried, and if not me, it would definitely catch the fire.