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noquacks 03-09-2011 03:17 PM

Question for a really smart electrician/physicist
 
Not really related to a DIY project, but was hoping to get an answer just the same for this......heres a link to a story where a guy apparantly was "saved" from a 14,000 V jolt of electricity from wearing rubber shoes.

:http://www.villagevoice.com/2010-04-...-snuff-film/3/

I always understood that say, rubber shoes wont save you from a jolt of lightning, so then could we attribute this guy as having been saved by his rubber shoes???

Lightning has about 1 billion volts. also, has 20,000 amps -300,000 amps. Maybe thats the difference, guys??

Thanks!

fsae0607 03-09-2011 03:52 PM

To me it seems that the metal cage he was in was grounded, so the electricity was channeled away from him and safely to ground. From what I picked up from the story, the generator blew when it short-circuited on the "condor" thing. Even barefoot, he would have felt a small jolt. But that's the whole purpose of grounding: to channel a fault safely away from a person and to ground.

a7ecorsair 03-09-2011 03:58 PM

Have you ever wondered why birds can sit on a high voltage line and not get shocked to death? Same situation and the shoes had no part.

Jackofall1 03-09-2011 04:04 PM

Yes, I would bet what did save him, was the rubber tires on the condor, not the soles of his boots, whole different story had things been wet.

Ever see the story on how they service the high tension wires from a helicopter, absolutely wild, but they connect a platform from the helicopter to the wire, the service man works on the platform while the helo is hovering at the same elevation and the other side of the platform connected to the wire.

The only thing they worry about at that point is static discharge.

Mark

davido30093 03-09-2011 05:08 PM

Any time there is more than one path to ground, electricity will always seek the path of least resistance.

AllanJ 03-09-2011 05:16 PM

Possibilities:

1. Currrent would have gone through Jason Welin's hands, electrocuted him, and exited via his feet and down the metal frame of the cherrypicker (condor) except his rubber shoes stopped that current path.

2. Current went directly to the frame of the cherrypicker and Jason Welin was not in the path of least resistance.

3. Because the earth is not that great a conductor, different spots on the ground surface were at varying voltage potentials up to about 14,400 volts maximum difference once contact was made up above and given that various pieces of movie equipment sat here and there on the ground.

4. The 120 volt and/or 240 volt movie lights and equipment were fried by the 14,400 volt line current coming through the movie equipment and jumping through the insulation of the 120 and 240 volt wires attached.

5. John Lamensdorf was killed and Brian Streem was injured from the current from the 14,400 volt line coming through movie equipment they were holding on to and/or movie electrical lines near them together with the differing electric potentials of the exact spots of the ground on which they were standing.

6. At that time there was no danger related to the current from the generator per se. The entire problem was caused by accidental touching of a 14,400 volt electrical line nearby that was not part of the equipment and not part of an attempted tie-in.

MLMIB 03-09-2011 05:55 PM

amperage is what kills you and stops your heart, the amperage that did go through him didn't go over his heart. He's lucky as anything, that said.

Jim Port 03-09-2011 06:00 PM

Quote:

Originally Posted by davido30093 (Post 606171)
Any time there is more than one path to ground, electricity will always seek the path of least resistance.

I really wish people would understand that electricity takes ALL paths. It is just in proportion to the resistance.

noquacks 03-09-2011 06:04 PM

You guys are great! Thanks! So, I didnt get it from the article, but was there mention of the amperage? Would that compare to that of a lightning bolt which is like, 3000,000 amps? I doubt it, huh......

I mean, this guy keeps bringing up how his buddy was "saved" once in a parking lot when a bolt of lightning hit a car just next to him, knocking him down, yet unhurt. And when the paramedic told him his sneakers saved him thats when I told him the medic better stick to his profession as sneakers will never stop a bolt of 1 billion volts . Now, because of this article, my buddy feels it vindicates his belief that rubber soles are a life saver in lightning.......

noquacks 03-09-2011 06:13 PM

Quote:

Originally Posted by a7ecorsair (Post 606116)
Have you ever wondered why birds can sit on a high voltage line and not get shocked to death? Same situation and the shoes had no part.

Thanks. I understand about the Faraday Cage Effect, but how does the birds ona wire work?

a7ecorsair 03-09-2011 07:46 PM

Quote:

Originally Posted by noquacks (Post 606214)
how does the birds ona wire work?

Voltage is a difference of potential (EMF) between two points and since the bird is sitting on the point of reference there is no difference of potential. If I had the bird hold one probe from a meter with a 10 megohm input impedance in his beak and I grounded the other and then got the bird to land on a 100,000 volt transmission line, it would give him a darn good shock. He would feel 10 milliamps of current. So, as long as you don't measure the bird's voltage he will be just fine.

AllanJ 03-09-2011 08:06 PM

Quote:

Originally Posted by Jim Port (Post 606201)
I really wish people would understand that electricity takes ALL paths. It is just in proportion to the resistance.

Instead of "path of least resistance" I should say that at the time there was no path through Jason Welin with a resistance low enough that enough milliamperes would flow so as to electrocute him. One example of such a path: From the 14,400 volt electric line to the movie prop to its guy wire to Jason's hand holding the other end of the guy wire through Jason to his rubber shoe soles to the floor of the cherry picker cab down the cherry picker then along the outside of the wet tire of the cherry picker vwhicle and into the mud.

Meanwhile some current from the 14,400 volt line may have gone through the movie prop, through the insulation of some 120 volt wires strung through the movie prop for lights, through the generator system, and through the insulation of other wires in a movie lamp post that John Lamensdorf happened to be leaning on. The current went through his body, electrocuting him, and down through his wet leather shoes into the ground where he was standing.

davido30093 03-10-2011 10:27 AM

Quote:

I really wish people would understand that electricity takes ALL paths. It is just in proportion to the resistance.
That is exactly right, but when one path has very low resistance relative to the other paths, MOST of the current will go through the path of least resistance.

noquacks 03-10-2011 03:59 PM

Thanks, again, guys. You have explained it well, and promptly. I appreciate it very much.
You have proven yous are really smart electricians as well as physicists!!

WDR 03-11-2011 09:51 PM

The amperage and voltage Both matter, a car battery can deliver over 200 amps. That amperage is more than enough to kill you. But I have never heard of anyone electrocuted by a car battery. The voltage is low enough that the resistance of skin stops the electricity.


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