Wire loops at insulator

They reduce corona discharge from all of the sharp points on the hardware that fastens the conductor to the insulator. The electric field near a small radius conducting surface (i.e. a sharp point) is much higher than near a larger radius. If this field strength exceeds the breakdown level of air, you get corona discharge as the air is ionized. These loops provide a larger radius and shield the objects in their immediate vicinity by creating a nearly zero potential gradient in this region.

Yes. I've seen birds on 26 kV but I can't recall seeing them on 34.5 kV. They might sit there in dryer climates, but given our weather, I think the cutoff lies somewhere in this region.

From what I hear about overloaded transmission lines it could simply be they are too hot to sit on. They are also pretty big. Birds seem to have a range of perch sizes they like.

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something

Local distribution is 20.8kV & 12.5kV and I see birds all the time on the lines. West of me a few miles it is 34.5kV but I never paid attention to birds. Now I guess I will keep an eye out and see if I ever see birds on those lines.

Matthew

Others have answered.

It is somewhere between 33 kV and 132 kV in the UK. Birds do perch on the 33 kV lines, but never on 132 kV. I did here a story of an engineer who used this knowledge to win a bet with another engineer. They were travelling by train on a railway line that ran parallel to a 132 kV line. One engineer saw a couple of birds perched on the line, and turned to the other engineer and said "I bet that line is dead". The other one said "If you can prove that statement I will buy you lunch." several miles along they came to a terminal pole on the line. There on the terminal tower was an earthing harness applied to the line.

John

Paul has it right. There is a combination of voltageand bird size that would result in corona from wing and feater tips as well as beaks. Feathers will "crawl" in high fields and this would be very uncomfortable. I haven't asked the birds but humans in high 50/60Hz fields have reported this "crawling" sensation due to body hair movement (only hair- no substitute for Viagra)

in article r4nIc.1007529$Pk3.885738@pd7tw1no, Don Kelly at snipped-for-privacy@peeshaw.ca wrote on 7/11/04 7:55 PM:

Last time I had that "crawl" it was a long way from any power line. I was fishing. Nevertheless, I ran for the cab of my pick up truck before the storm hit. Do graphite fishing rods protect against lighning?

Bill

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something

Local distribution is 20.8kV & 12.5kV and I see birds all the time on the lines. West of me a few miles it is 34.5kV but I never paid attention to birds. Now I guess I will keep an eye out and see if I ever see birds on those lines.

Matthew

"Matthew Beasley" wrote in news:pGHIc.736$ snipped-for-privacy@newsread1.news.pas.earthlink.net:

I have some 500kV lines near the house....have never saw a bird on them.

---------------- Your pickup cab does a much better job of protecting you. I wouldn't trust the rod to do any more than say "here I am, come and get me" :)