Path: utzoo!attcan!uunet!aplcen!uakari.primate.wisc.edu!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!cica!iuvax!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!phil From: phil@ux1.cso.uiuc.edu Newsgroups: sci.electronics Subject: short circuit experiences Message-ID: <34700035@ux1.cso.uiuc.edu> Date: 21 Oct 90 19:58:00 GMT Lines: 69 Nf-ID: #N:ux1.cso.uiuc.edu:34700035:000:4002 Nf-From: ux1.cso.uiuc.edu!phil Oct 21 14:58:00 1990 *** WARNING *** DO NOT ATTEMPT ANY OF THE EXPERIMENTS DESCRIBED HEREIN *** Back in my college days, which were just an extension of my high school days, I was sometimes rather destructive. I was the type to short circuit 110 volt plus with a loose solder bridge and leave the devices unplugged. When they were plug back in, the results were a bright flash, some solder vapors, and charred rosin residue blackening the outlet. I also made a shorting device out of a heavy duty 110 volt plug, some 10 gauge wire, and a 20 AMP "3 way" switch connected in parallel. I would plug the device in while open, then close the switch. Thus I did not have to see the sparks (instead they were burning up the switch contacts). The life expectancy of the device turned out to be about 50 uses on average. The usual failure mode was the switch fused in the closed position. That resulted in sparks on the (n+1)th attempt. Usual experiences with this device included a clanging sound from the walls. I suspected this to be the sudden rise and fall of the magnetic fields on the conduits. Most circuits I ever shorted were wired in conduits. One experience I had while using shorting device number 3 differed from the others. I was staying in a 4-person dorm room with only 1 roommate since it was summer. I was going home that weekend but my roommate was not. I decided to leave him a "complication" for the weekend. I shorted out the outlet circuit in room 1. There was the usual clanging sound, the blink of the lights (on another circuit but obviously on the same phase), and the shutdown of other devices on that circuit. I went into room 2 and found things there still working, and shorted that room's circuit in the same way with all the same effects. But the overhead lights were still on and I would have liked to get them off as well. After puzzling over the light circuit, I tried to turn on the light over the mirror and found it to be working. I hoped that this light was on the same circuit as the overhead lights. It had a utility outlet such as for an electric shaver so I was in luck. As I shall describe in the next paragraph, I was never able to determine this for sure. I plugged the shorting device (in open state) into the utility outlet. So far all was normal. Then I threw the switch to close the circuit and this is when the "fun" began. Instead of the expected clanging sound, I heard instead a loud buzzing and rattling combination sound. All the lights in the room went out when I closed the circuit, but the sound continued. After a few seconds of this, I decided something was wrong (gee, how obvious) and opened the switch. The buzzing and rattling sound stopped, and all the lights (including the one over the mirror) came back on. The wire portion of the shorting device was extremely hot. The plug body itself was so hot I figured I should not touch the prongs. I could feel radiated heat from it. I estimate the time of this shorted circuit to be about 5 seconds. I hid the shorting device in my suitcase and prepared to take it home (as I usually did on home trips anyway) with plans of retiring it and dissecting it as well (to see what damage took place to the switch contacts). I never did get around to doing that. On my way out, I went through the lobby and overheard a couple people talking about the "power failure". I asked them what they saw, and they said "the power went out for a few seconds". This was a dorm building with about 300 rooms, many of which were the double type for 4 people. It had its own set of three substation type transformers in the garage level under the first floor. How many amps do you think might have peaked out through this circuit? Why might the circuit breaker have not tripped? What damage to anything might have taken place (besides my device)? --Phil Howard, KA9WGN-- | Individual CHOICE is fundamental to a free society | no matter what the particular issue is all about.