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#199845 - 03/11/11 04:20 AM Power line induction
Vlado Offline

Registered: 02/28/11
Posts: 28
Loc: Croatia
Interesting video clip of HV induction.
Do not open gas tanks when you are below HV power lines... whistle

Arc Flash PPE Clothing, LOTO & Insulated Tools
#200139 - 03/21/11 04:04 PM Re: Power line induction [Re: Vlado]
mikesh Offline

Registered: 06/07/06
Posts: 614
Loc: Victoria, BC, Canada
Capacitive coupling is pretty interesting too. Maybe 17 years ago I was working on a big project and we were well into the finishing of the building. I was testing the parking lot lights and of course 1 did not light. I grabbed a 12 foot step ladder and stood it beside the problem lamp standard. I leaned over to undo the canopy and I got a pretty sharp tingle as soon as I touched it.
Immediately I am cursing the moron that did not bond the lamp standard. At least until I opened the hand hole and found the standard was properly bonded.
So here I was standing on the ground and I did not get a poke and wondering what was up. Up was where I was headed and again as soon as I touched the lamp I got buzzed again.
I was flabbergasted. Next I touch 1 lead on the luminaire and read 120 volts with only 1 lead touching anything. AAARGHH what is going on here I yell in unrepeatable construction jargon. I got down off the ladder and touch the volt meter lead to the standard 70 volts. Back up the ladder and 120 volts. Raise the other volt meter lead up over my head and 160 volts. At this point I was just about to call for the loony truck that I look up. 239 KV transmission lines over my head.
I was shocking the lamp standard not the other way around.
I decided then that I would never live close to a transmission line. BTW if you took a fluorescent tube and touched 1 end to the luminaire and the other to the sky it would light the tube.
Capacitive coupling lesson illustrated.

#200247 - 03/26/11 07:36 AM Re: Power line induction [Re: Vlado]
Vlado Offline

Registered: 02/28/11
Posts: 28
Loc: Croatia
Yes,so called capacitive coupling is the key factor which enables HV induction via AC E-field from overhead power lines here.More generally it is electromagnetic induction but E-fields are more important than B-fields in such cases.In substations it is an ordinary thing.I have been in 400 kV substation.For example, when you wear insulating shoes but don't wear insulating gloves,and you reach down to touch the ground,you get very unpleasant electric shock!


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