[TowerTalk] Power lines, hawks, and fire ignition (slightly off-topic)

[Gene Smar]

Bill et al:

     Animals like hawks (largish wing spans) and squirrels frequently meet
their demise by climbing onto or alighting on an energized power line (no
problem there) and then permitting their wing feathers or tails to contact
the pole (phase-to-ground fault) or another phase wire (ph-to-ph fault).

     I recall an article in a trade mag for the electric utility industry
over 25 years ago about a utility in So Cal (SoCalEd?) or Arizona that had
problems with eagles perching on their medium voltage transmission lines
(appr 69 kV, meaning relatively close-spaced wires and short distances to
the wood pole) and causing faults and outages due to their large wing spans.
The utility fought with animal rights activists and environmentalists for a
while until the utility came up with the idea of constructing platforms at
the very top of the double-pole structures.  As a result, the outages
ceased, the birds had a safe roosting place where they actually built nests,
and that was the end of the issue.

     The question I have about this report is how do the authorities KNOW
that it was a bird that caused the fire.  Have they been able to get close
enough to the point of origin to find the carcus?  (That's how we in the
utility industry were able to determine the cause of our line faults - we
found the poor little fried squirrel on the ground beneath the faulted
line.)  Inquiring minds want to know.

73 de
Gene Smar  AD3F
(former EE for an electric utility)

----- Original Message ----- 
From: "Bill VanAlstyne" <w5wvo at cybermesa.net>
To: "_Mailing List Tower-Talk" <towertalk at contesting.com>
Sent: Tuesday, July 20, 2004 12:53 PM
Subject: [TowerTalk] Power lines, hawks,and fire ignition (slightly
off-topic)


> I couldn't help but wonder at this snippet from an AP newswire article in
> this morning's paper regarding how the Santa Clarita wildfire in
California
> supposedly started: "[The wildfire] was ignited when a red-tailed hawk
flew
> into a power line, was electrocuted and fell, burning, into brush."
>
> I know some of you guys on this list are extremely knowledgeable about the
> basic physics of electromagnetism. Could somebody please explain how a
> single high-tension AC wire can ignite a hawk? (Yuck.) Where does the
> current flow -- I mean, between what and what?
>
> Bill / W5WVO
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