We also use the pop nuts in electrical distribution boxes. The first time I saw them in the civilian world, was on D-box copper bars. Each phase and the PEN, (Ground and Neutral bar) had holes drilled in them and the pop nuts inserted. Cables are connected to the bars by large bolts, screwed into the pop nuts. Fast, cheap and dependable. And no lost hardware when you remove the bolt. Without fail, when a bolt was removed before the pop nuts came about, the nut, flat washer and lock washer fell to the bottom of the D-box. All fine and good, but sometimes we have to work with live circuits. I once, (under much pressure, and having complained unsuccessfully to two higher levels of command) had to replace a single pull, single throw, three phase circuit breaker, from live circuits. I lost several pounds of sweat, doing the job. High voltage is not a friend of mine. During the replacement portion of the job, the last nut, washers and bolt, would not start. The tools were insulated. I pushed too hard on the ratchet, and it pushed the nut out of the housing, and it fell down, between two two high voltage copper bars. The nut, (a 24MM) turned into plasma. It blinded me, destroyed my face shield and made many fine holes in my protective jacket. Those kind of accidents would never have happened with pop nuts. I am kinda partial to pop nut nowadays. Oh, yeah. The small town where we were working at the time had to spend several hours without electricity, until someone else could effect repairs. I had to go home and change my underwear.