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I thought Charles Proteus Steinmetz played a significant role in the debate with Edison over the use of AC or DC for long distance transmission of electrical power. Perhaps both Steinmetz and Tesla were involved?
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A friend and I were arguing the other day about what happens if you touch a
hot lead but do so with a fully insulated tool. Does one feel the shock?
Also what happens if you don't have the insulated tool but you were
standing on a non conductive rubber mat? We were basically arguing over
110 and 220v situtions. Thanks.
*haven't got anything better to wonder about? you can touch a hot lead all you want (don't!!) with no worry unless you are also connnected to the neutral or ground.You don't need an insulated tool either, you can grab it.You hopefully don't need an insulated mat either.But conditions vary, and there are situations where none of this is completely true. Just don't try it. It's really not worth much to find out if I'm right or not.MD
*Done it and never got hurt. (well maybe sometimes.) It's best to do it with your tongue.(insert same disclaimer as Mad Dog here)
*Birds sit on uninsulated, 330,000 volt power lines all the time.Jerry
*In another topic I posted about a recent "Suicide Missions" show on television about linemen. There is a "barehanded" technique they use where they connect themselves to the line while standing on a superinsulated boom or sitting on a helecopter platform. They wear a metallized suit to prevent induced currents and draw an arc to a clamp then attach it to the line.By the way, I am talking about 500,000 volt lines...
*I wonder if this is still possible with high voltage AC lines. As the voltage fluxuates from 500,000V above ground to 500,000V below ground potential, do you get fried?
*They are so insulated from ground they are not affected-however, if they get closer than 11'6" to the supporting structure they will get killed from a flashover. They wear the suit because of the electric field around the wires. It was something to see a helecopter pilot hovering along side the line while the lineman worked on it. They sit on a platform right by the landing gear and everything is at 500,000 volts-the helecopter, people, etc.They also showed a rescue exercise on the same line.
*There is a newscaster in an LA hospital with Fourth Degree Burns on 20% of her body. (That's no typo--but I've never heard of fourth degree burns before.) She has lost one arm and several fingers and toes. She may loose both feet and her other hand. The microwave antenna on the van she was in touched a 33,000 volt line.When I worked for a power company, linemen used rubber gloves for 4,000 volts. The gloves were magnafluxed periodically to test for failures. 18" Hot sticks were required for 12,000 and above. 64,000 and above was never worked on hot.There is no difference between the ground potential for 120v and 240v since the 240v is the potential between legs. Each leg is 120v to ground.
*Thanks for the great answers. Sorry to hear about the girl in LA. Just for the record, we weren't thinking about trying "it." With an nine month old I'm playing everything pretty safe these days. DB
*I thought the high voltage transmission lines were all DC. Less loss to impedence.What I'm thinking is: If you're touching a high voltage AC line and you get charged to whatever the line voltage is and then, the line voltage changes (120 times ever second), do you feel it. I don't know how fast the human body can be "charged" by a high voltage wire. Sounds like a petefest game to me.
*Anyone ever hear of this....A lineman from our town was killed recently while taking down heavy high voltage line from big towers. He was killed by STATIC electricity which apparently builds up on the miles of wire they were working with. The wires were completely disconnected from the voltage source at the other end. Apparently there is a certain procedure you have to follow to bleed this electricity out of the lines before you handle them and they failed to do this. He was killed as quickly as if he had touched a regular hot power line.
*G.Lalonde - Are you certain he wasn't killed by induction from an energized high-volt line nearby? I recently read the details of an accident in the IAEI journal, an electrician working on a disconnected 230 Kv line was killed by induction in the line caused by an energized 287 Kv line 125 feet away....the electrician had not followed proper procedure by temporarily grounding the line he was working on. The byline on the story said "Bonneville", wherever that is. The similiarity in stories leads me to wonder if it is the same incident..............Lee
*No, they are AC. That was the whole issue between Thomas Edison (who advocated DC, which is safer to handle) and ...(some one else big at that time). Edison invented the electric chair to 'scare people off of AC current' by showing how dangerous it was. The whole thing backfired on him: - people were disgusted with him that he invented a killing machine - the other design (AC) worked better over long distances So we use AC current today for power transmission and we have all pretty much forgotten about Edison's DC design. And we have an electric chair, if we want to use it.
*Norm:You sound like you're more knowledgable about this stuff than I am. But, I thought that the advantage of AC was that it could easliy be stepped up and down to travel the long distances. I thought that AC does lose more power to impedance than DC does to resistance and that DC has been chosen for those long, long runs across the country.
*Short legs are an advantage sometimes. The birds are actually in a current path if they have both legs on the line. However, the short distance of wire between the bird's legs has so little resistance that the parallel current through the bird (who has relatively high resistance) is nil, the vast majority of current still flowing through the wire. Now if the bird could stretch those legs quite a distance, he might be frying instead of flying.
*i and ...(some one else big at that time). Nicholas Tesla, genius wild man from Yugoslavia
*What happened in this case is that the mast was raised into contact with the 34.5kV line. The reporter in the front passenger seat of the news van was OK until she decided to get out to see what that big zapping noise was all about. That's when she bypassed the insulating rubber tires of the van and completed the circuit between the van body and the ground. Even walking around on the ground near a downed power line can be dangerous, because your two feet can span a substantial voltage gradient.-- J.S.
*I thought Charles Proteus Steinmetz played a significant role in the debate with Edison over the use of AC or DC for long distance transmission of electrical power. Perhaps both Steinmetz and Tesla were involved?
*I think it was George Westinghouse after he put generators at Niagra Falls.It was said that if all bosses treated their employees as Mr. Westinghouse treated his, there would have been no need for unions.
*Westinghouse funded Tesla's research and had him develop plans for the Niagra station. This was after Tesla and Edison had butted heads about AC or DC, and had parted ways. Electricity was an exciting new technology and Westinghouse, of railroad fame and wealth, was looking to get into it, so he hired Tesla. Generally, the company founded by Edison and his ideas has developed into GE, and Tesla's theories and developments came to be in Westinghouse. Tesla's first employer when he came to this country was Edison, but it didn't last long.I don't know offhand where Steinmetz fit in.Lee
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There are a couple of huge DC power transmission lines in the
US. But most are AC.