Fatal Shock

by phymathlover
Tags: bird, current, fatal, potential difference, shock, transmission lines
phymathlover is offline
Feb24-14, 01:43 PM
P: 11
A bird perches on a bare high power line and nothing happens to it. A man standing on the ground touches the same line and gets a fatal shock. This is supposed to be because there is potential difference between the ground and the line which the man touches but similarly, isn't there also a potential difference between the line and the air to which the bird is exposed and thus a potential difference and so shouldn't the bird also get a shock? I know that air is an insulator but since the high transmission lines have large electric fields around them so this should cause breakdown of air?
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SteamKing is offline
Feb24-14, 02:39 PM
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P: 5,542
The breakdown voltage for air is much larger than the line voltage. The field strength for the breakdown of air is greater than 3 MV/m. If electric transmission lines grounded with the air, it would be impossible to transmit electricity in this fashion without zapping everything near the lines.
UltrafastPED is offline
Feb24-14, 06:48 PM
P: 1,305
Also note that you, as a person, are not a great insulator ... and being the path of least resistance is from the line voltage thru you to the ground.

If a bird is big enough to touch two wires simultaneously you will get roast buzzard!

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