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#161
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In article , "K Wind"
writes: "Paul Burridge" wrote in message .. . The question seems daft, but bear with me, gentlemen. Has anyone ever had an electric shock that they feel lucky to have survived? Would 1,500VDC with 6mA capability flowing through one arm and out the other be considered lethal? At one time, I knew how much current was considered lethal, but have forgotten. Think of "30-30" as a mnemonic. If the source has over 30 Volts and can supply over 30 milliamperes through the cardiac region, you will go into cardiac fibrilation. High voltage with little supply current will affect the nerves and the resulting muscle spasms can cause other kinds of injuries, some that may be fatal. DON'T DO IT. PAY ATTENTION! Len Anderson still living in the same reality I was born into... |
#162
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In article , "RP Henry" richard.p.henry@saic dot
com writes: "Tom Sevart" wrote in message ... "WB3FUP (Mike Hall)" wrote in message ... 10KV to fire magnetron in counter battery radar. Took six marines to stop me from burying my screw driver in the chest of the asshole that thought it would be cute to push the radiate button. I remember hearing the story of an Air Force tech working on a 30' radar dish. For some dumb reason, someone energized it and promptly microwaved him to death. Some of these stories are hair rasing... and I'm too much of a weenie to stick my tongue on a 9V battery... A Raytheon corporate legend is that one of the engineers discovered the microwave oven principle when a radar melted a chocolate bar in his shirt pocket. That's been an Urban Legend for decades...probably a PR plant from someone at Raytheon's Santa Barbara, CA, division that deveeloped the RadaRange (originally a trademark of Raytheon before they sold that consumer line to Amana). ======== While all the war stories and chit-chat are entertaining, please consider a real-life tragedy that happened to a TV broadcast van in Los Angeles last year. The van had stopped and erected its field-to-transmitter link dish to Mount Wilson where the TV transmitter was. Standard procedure here to get a clear shot above buildings and obstructions, all the field vans have such erectable dishes. Nobody in the field crew seems to have noticed that the van was under a "high-line" of higher-voltage lines common in local area power distribution. The dish and its two-section small crane came in contact with the high-line. Somehow the kind of contact sent a good-sized electrical power flow down into the van. A woman reporter was severely burned in addition to being knocked unconscious...burns severe enough to require amputation of part of an arm and part of a leg. She survived but spent many months in the hospital and physical therapy, had to use a wheelchair to get around even though active and healthy and not yet 40 before the accident. This incident was clearly a result of STUPID NON-ATTENTION by the TV field crew. That high-line distribution is common all over this city and adjoining cities. To erect the link dish right into power wiring of any kind was just compounding the stupidity. I mention this because amateur radio nearly always involves outside antennas in urban areas close to utility power wiring on poles. The possibility of fatal or terrible electric shock isn't confined to some radio-electronic box interior...it exists out in the open, in plain sight. Keep it in mind to avoid frying that mind. Len Anderson retired (and still living) electronic engineer person |
#163
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In article , "RP Henry" richard.p.henry@saic dot
com writes: "Tom Sevart" wrote in message ... "WB3FUP (Mike Hall)" wrote in message ... 10KV to fire magnetron in counter battery radar. Took six marines to stop me from burying my screw driver in the chest of the asshole that thought it would be cute to push the radiate button. I remember hearing the story of an Air Force tech working on a 30' radar dish. For some dumb reason, someone energized it and promptly microwaved him to death. Some of these stories are hair rasing... and I'm too much of a weenie to stick my tongue on a 9V battery... A Raytheon corporate legend is that one of the engineers discovered the microwave oven principle when a radar melted a chocolate bar in his shirt pocket. That's been an Urban Legend for decades...probably a PR plant from someone at Raytheon's Santa Barbara, CA, division that deveeloped the RadaRange (originally a trademark of Raytheon before they sold that consumer line to Amana). ======== While all the war stories and chit-chat are entertaining, please consider a real-life tragedy that happened to a TV broadcast van in Los Angeles last year. The van had stopped and erected its field-to-transmitter link dish to Mount Wilson where the TV transmitter was. Standard procedure here to get a clear shot above buildings and obstructions, all the field vans have such erectable dishes. Nobody in the field crew seems to have noticed that the van was under a "high-line" of higher-voltage lines common in local area power distribution. The dish and its two-section small crane came in contact with the high-line. Somehow the kind of contact sent a good-sized electrical power flow down into the van. A woman reporter was severely burned in addition to being knocked unconscious...burns severe enough to require amputation of part of an arm and part of a leg. She survived but spent many months in the hospital and physical therapy, had to use a wheelchair to get around even though active and healthy and not yet 40 before the accident. This incident was clearly a result of STUPID NON-ATTENTION by the TV field crew. That high-line distribution is common all over this city and adjoining cities. To erect the link dish right into power wiring of any kind was just compounding the stupidity. I mention this because amateur radio nearly always involves outside antennas in urban areas close to utility power wiring on poles. The possibility of fatal or terrible electric shock isn't confined to some radio-electronic box interior...it exists out in the open, in plain sight. Keep it in mind to avoid frying that mind. Len Anderson retired (and still living) electronic engineer person |
#164
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On Sat, 09 Aug 2003 12:11:19 -0700, Mark Fergerson
wrote: Now that you've explained what you meant, I'll mention that I must be on at least my fifth parallel Universe. Don't bother counting. You have a *lot* more to go, it seems. -- "I believe history will be kind to me, since I intend to write it." - Winston Churchill |
#165
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On Sat, 09 Aug 2003 12:11:19 -0700, Mark Fergerson
wrote: Now that you've explained what you meant, I'll mention that I must be on at least my fifth parallel Universe. Don't bother counting. You have a *lot* more to go, it seems. -- "I believe history will be kind to me, since I intend to write it." - Winston Churchill |
#166
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Ian White, G3SEK wrote:
. . . An interesting thing happens when you switch off to isolate part of the house wiring, and then cut the "dead" three-wire cable. (We call it "flat twin and earth". It has PVC-insulated hot and neutral wires with a bare ground wire in between, all in a flattish grey or white PVC sheath. Is this what you call "Romex"?) Yes, that's "Romex". The official designation is type NM (for Non-Metallic). 12 gauge wire, for 20 amps maximum, is "12-2 with ground" and 14 gauge, for 15 amps, is "14-2 with ground". Those are the most common sizes for residential lighting and outlet circuits. If you cut the hot and ground wires together, nothing happens; but if you cut the neutral and ground wires together, the RCD trips. That's a puzzle the first time it happens, but it's because that cable isn't quite as "dead" as you think. the isolating switches interrupt only the hot wire, so the neutral and earth are still being shared with everything else that's switched on in the house. Does that happen in the USA, or do you have two-pole isolating switches for individual sub-circuits? I don't quite follow where you're cutting the wires or where the RCD is located. Here, you can get a GFCI as either a circuit breaker you install in the service box to protect a whole circuit, or incorporated in a duplex outlet. Both are easily identifiable by the conspicuous test button. The breaker differs from an ordinary breaker in that the neutral wire is also routed through it. Circuit breakers interrupt only the "hot" wire. It's been a long time since I studied the code (NEC - National Electrical Code), but I'm sure that switching the neutral is still a no-no. Neutral wires are all brought back to the service box, where they're all connected to the central power feed wire. The safety grounds are brought back to the service box separately, where they're connected to the same point as the neutrals. Neutral and safety ground are connected together only at the service box, nowhere else. This isn't totally idle curiosity. If there's an electrical problem while we're staying with the in-laws in Atlanta, I'm the one who's supposed to know about these things... I'd at least get a home-handyman book on electrical wiring, and a real code book if you'll be doing anything other than pretty simple wiring. The rules are quite complex, dictating things like how close to a junction box wires have to be supported, how they can be routed, what size junction box is required for various combinations of entering/exiting wires, etc. In Oregon, wiring can legally be done only by the homeowner or a licensed electrician, but each state and many localities have their own rules. I think all, or just about all, the states now at least have agreed to use the NEC. (You're probably technically forbidden to touch the wiring, depending on Georgia and Atlanta regulations.) The presence of non-code wiring could result in non-payment of insurance if a home were to have an electrical fire. I wired the addition to our home, which involved adding seven circuits including outside outlets and lights. I also replaced and upgraded the service box. Those jobs were done with electrical work permits, and both were inspected and passed. So I have done a bit of this before. But it was a lot of years ago now, the code evolves, and my memory fades. Roy Lewallen, W7EL |
#167
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Ian White, G3SEK wrote:
. . . An interesting thing happens when you switch off to isolate part of the house wiring, and then cut the "dead" three-wire cable. (We call it "flat twin and earth". It has PVC-insulated hot and neutral wires with a bare ground wire in between, all in a flattish grey or white PVC sheath. Is this what you call "Romex"?) Yes, that's "Romex". The official designation is type NM (for Non-Metallic). 12 gauge wire, for 20 amps maximum, is "12-2 with ground" and 14 gauge, for 15 amps, is "14-2 with ground". Those are the most common sizes for residential lighting and outlet circuits. If you cut the hot and ground wires together, nothing happens; but if you cut the neutral and ground wires together, the RCD trips. That's a puzzle the first time it happens, but it's because that cable isn't quite as "dead" as you think. the isolating switches interrupt only the hot wire, so the neutral and earth are still being shared with everything else that's switched on in the house. Does that happen in the USA, or do you have two-pole isolating switches for individual sub-circuits? I don't quite follow where you're cutting the wires or where the RCD is located. Here, you can get a GFCI as either a circuit breaker you install in the service box to protect a whole circuit, or incorporated in a duplex outlet. Both are easily identifiable by the conspicuous test button. The breaker differs from an ordinary breaker in that the neutral wire is also routed through it. Circuit breakers interrupt only the "hot" wire. It's been a long time since I studied the code (NEC - National Electrical Code), but I'm sure that switching the neutral is still a no-no. Neutral wires are all brought back to the service box, where they're all connected to the central power feed wire. The safety grounds are brought back to the service box separately, where they're connected to the same point as the neutrals. Neutral and safety ground are connected together only at the service box, nowhere else. This isn't totally idle curiosity. If there's an electrical problem while we're staying with the in-laws in Atlanta, I'm the one who's supposed to know about these things... I'd at least get a home-handyman book on electrical wiring, and a real code book if you'll be doing anything other than pretty simple wiring. The rules are quite complex, dictating things like how close to a junction box wires have to be supported, how they can be routed, what size junction box is required for various combinations of entering/exiting wires, etc. In Oregon, wiring can legally be done only by the homeowner or a licensed electrician, but each state and many localities have their own rules. I think all, or just about all, the states now at least have agreed to use the NEC. (You're probably technically forbidden to touch the wiring, depending on Georgia and Atlanta regulations.) The presence of non-code wiring could result in non-payment of insurance if a home were to have an electrical fire. I wired the addition to our home, which involved adding seven circuits including outside outlets and lights. I also replaced and upgraded the service box. Those jobs were done with electrical work permits, and both were inspected and passed. So I have done a bit of this before. But it was a lot of years ago now, the code evolves, and my memory fades. Roy Lewallen, W7EL |
#168
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On Fri, 08 Aug 2003 10:05:43 +0100, Paul Burridge
wrote: On Fri, 08 Aug 2003 03:29:47 GMT, Eric Immel wrote: Paul, are you asking if anyone has been killed, then revived? That's pretty close to what I'm getting at. What I *am* actually get at is that theoretical physicists are coming around to the rather extraordinary view that one cannot from one's own perspective be killed by any sudden and dramatic life event. No matter how bad the shock, you will always 'come around' to find that you've survived. The tricky bit is that you'll probably have found yourself in a different reality to the one you left. In the one you've left, observers will see your cold, dead, smoking body lying sparko on the ground. Your relatives will grieve, your obituary will be written. But *you* won't know anything of that. You'll just believe you've had a lucky escape; you'll go home and tell your friends and family all about it and years later maybe you'll tell others via the Internet. Sounds nuts? Incredible as it may seem, the majority of physicists currently Well that is funky! Got electrocuted pretty well as a teenager. Fiddling about with an ex-Army ZC1 set I'd converted to mains, managed to take 230vac from arm to arm for what seemed like several minutes, but was probably a second. Was sick, shaking, sore and sweaty for a couple of hours, still had sore muscles for several days. Not at all funny. But the universe I came back to seemed pretty normal. Did the NDE thing after drowning in the school pool as a kid though, can pretty clearly recall looking down on myself, and the teacher "bringing me back" I suspect she still wanted to hassle me about the unfinished homework, and drowning was not going to be accepted as an excuse! Still the same universe though! Barry Lennox |
#169
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On Fri, 08 Aug 2003 10:05:43 +0100, Paul Burridge
wrote: On Fri, 08 Aug 2003 03:29:47 GMT, Eric Immel wrote: Paul, are you asking if anyone has been killed, then revived? That's pretty close to what I'm getting at. What I *am* actually get at is that theoretical physicists are coming around to the rather extraordinary view that one cannot from one's own perspective be killed by any sudden and dramatic life event. No matter how bad the shock, you will always 'come around' to find that you've survived. The tricky bit is that you'll probably have found yourself in a different reality to the one you left. In the one you've left, observers will see your cold, dead, smoking body lying sparko on the ground. Your relatives will grieve, your obituary will be written. But *you* won't know anything of that. You'll just believe you've had a lucky escape; you'll go home and tell your friends and family all about it and years later maybe you'll tell others via the Internet. Sounds nuts? Incredible as it may seem, the majority of physicists currently Well that is funky! Got electrocuted pretty well as a teenager. Fiddling about with an ex-Army ZC1 set I'd converted to mains, managed to take 230vac from arm to arm for what seemed like several minutes, but was probably a second. Was sick, shaking, sore and sweaty for a couple of hours, still had sore muscles for several days. Not at all funny. But the universe I came back to seemed pretty normal. Did the NDE thing after drowning in the school pool as a kid though, can pretty clearly recall looking down on myself, and the teacher "bringing me back" I suspect she still wanted to hassle me about the unfinished homework, and drowning was not going to be accepted as an excuse! Still the same universe though! Barry Lennox |
#170
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