We very often see flocks of birds perched in trees, on rooftops, on local power line wires, and even on radio antennas.

Figure 1 Birds often perch on antennas.

However, I have noticed that I never see birds coming to rest on high-tension power lines.

Figure 2 Birds don’t normally come to rest on high tension power lines.

I may have come across the reason on the NKT Photonics site. Please examine Figure 3, which shows power line wire temperature excursions when conditions go from normal service to an emergency.

Figure 3 This chart shows power line temperatures from normal service to emergency conditions.

The vertical axis of this chart shows temperatures as far down as 62°C, but even normal wire service temperatures are shown well above that. This may be normal service but it is HOT stuff.

I discussed in a previous post that biological harm can be incurred at only 50°C, well below the above wire temperatures. It’s no wonder that birds don’t perch on those wires. If I were a bird, you wouldn’t find me up there either.

John Dunn is an electronics consultant, and a graduate of The Polytechnic Institute of Brooklyn (BSEE) and of New York University (MSEE).

Wow, that is a lot more power loss than I realized. It is strong support for supporting the idea of interconnected microgrids with lots of distributed clean distributed power sources.

There is a New Yorker cartoon showing birds sitting in a row next to a sign saying “Buried Cable”

It is hard to believe that kind of temperature rise exist on the high tension line. That would spell a very high I2R loss. It would be interesting to know typical current flow, cross sectional and material makeup of the line itself. High Tension lines don’t typically have a conventional insulation or “jacketed” wire, they are bare essentially. I am wondering if a reason for the birds not landing on the high tension line is the electro static effects on the feathers or something else?

I once read an article that I can’t find anymore, but which cited long distance power line temperatures of 125°C. Today, I put the phrase “Powerline Temperature” into Google and the first search result that came up was:

“Operating temperatures can be 120°C or over 200°C with some of the more exotic (and expensive) cables used today. Also, high operating temperatures accelerate creep, which is a gradual expansion of the cable with time.”

Yes, indeed. The power losses are quite substantial.

It would be a very cold day if you saw icicles on those lines!

A somewhat related item: https://www.gocomics.com/herman/2021/09/03

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