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Reliability of underground power lines? - Page 3

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Posted by Mark F on August 17, 2010, 5:02 pm

On Mon, 16 Aug 2010 02:14:44 -0400, "John Gilmer"
(original poster referring to both high and low voltage stuff)

In addition, above ground failures are highly concentrated around bad
weather, whereas below ground doesn't seem to be as concentrated
around bad weather.  Thus, with underground you don't have to wait for
37000 other groups of 5 or fewer customers to get their stuff fixed
after a big storm.

Posted by John Gilmer on August 18, 2010, 2:52 am

In the sense that homes numbered in the thousands usually don't go out for
days at a time, that's true.

But something usually "triggers" an underground fairure.   Heat is
correlated with both transmission line and transformer failures.    Freeze
thaw  can damage direct buried underground lines.

In cities, heavy rains and put lines & splices and equipment that are
usually dry under water.

So the weather does have an impact.

That said, the problems with our service "drop" didn't seem to be correlated
much with anything although they tended to occur sometime after 8 pm.

Posted by vaughn on August 18, 2010, 11:29 am

It seems like John doesn't live in hurricane country.


Posted by clare on August 18, 2010, 10:35 pm

On Wed, 18 Aug 2010 07:29:34 -0400, "vaughn"

Or Ice Storm country.

Posted by Josepi on August 17, 2010, 7:36 pm

Two questions.

1) Are you sure the primary is 38kV underground?

2) What area are you in?


Back to my own neighborhood, there haven't been any underground failures of
the 38kv but a neighbor lost her transformer.   The first replacement had a
"bushing failure" and had to be replaced again.   They were without power
for about 5 days because of the transformers.

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