Comments on: Power Line Safety for Hungary’s Hawks

By: Jeb, FCD

Jeb, FCD — Mon, 31 Mar 2008 13:00:50 +0000

Thanks, JV et al, I appreciate the info.

By: Jim Thomerson

Jim Thomerson — Sun, 30 Mar 2008 21:37:40 +0000

I worked on an Army Corps of Engineers project which involved high tension lines in an area with high seasonal populations of bald eagles. We found a paper with measurements of eagle dimensions. We took this to the engineers and they designed power poles such that an eagle could not touch two hot spots at the same time. There were also things which would be put on the power lines to make them more visible.A Venezuelan friend told me of a problem with monkeys getting electrocuted. I gave him a copy of the eagle-friendly design study, but never heard any more about it.

By: charlie

charlie — Sun, 30 Mar 2008 19:11:13 +0000

Mr Vector is correct. Tony, underground cables are far more expensive to install and maintain. Also they are more vulnerable to lightning strikes and corrosion. I spent several years replacing underground power cables that were supposed to last 50 years but began to fail in 15.

By: bug_girl

bug_girl — Sun, 30 Mar 2008 17:37:48 +0000

This is interesting–I’ll have to check at the bird sanctuary and see if this is a source of injured raptors.

By: Johnny Vector

Johnny Vector — Sun, 30 Mar 2008 16:35:10 +0000

Jeb, they are electrocuted when they complete a circuit between two conductors. You are correct that for normal distribution lines there is no risk from perching on a single line. The problem comes about when they touch two lines at once, e.g. with a wingtip while taking off or landing.Solutions involve guarding areas where that can happen. (I learned all this from Google and friends just now, but it matches what I assumed was the answer.)A back of the envelope calculation I once did suggests that a large bird might have enough capacitance that perching on a single high-voltage (500kV or more) cross-country line would give it a nasty shock, maybe even enough to kill it. I have since noticed that I never see birds perching on cross-country lines (except on the ground wires at the top), so I suspect I’m right.

By: Tony P

Tony P — Sun, 30 Mar 2008 13:47:40 +0000

If I recall, don’t birds in general have some sort of magnetic sense? If so the high current AC going down those lines has to be throwing some serious magnetic energy. That would mess with a navigation system.Oh wait, that’s UFO’s.Seriously though I never understood why we don’t bury power lines everywhere. It makes no sense to string aerial cable anymore.

By: Jeb, FCD

Jeb, FCD — Sun, 30 Mar 2008 13:05:07 +0000

How are they electrocuted? What grounds them?We have residential lines in our backyard servitude that birds land on without being fried, and the lines aren’t jacketed.I am quite curious.