many years back, most of the electronic key/pbx systems had a fuse for every extension. you would open up the cabinet and there would a bunch of 4 or 8 port station cards with fuses on them. over the years these fuses slowly disappeared and were mostly jumped-out. one tech that i worked with said that every time he replaced a fuse, it would immediately blow, so he started jumping them out.

eventually someone asked him where he was getting his fuses and he replied "FROM LOU'S AUTO SUPPLY ON MAIN STREET"

!He didn't realize automotive fuses are rated for 12vdc!