Lightning Protection questions
On Sat, 08 Nov 2008 23:35:13 -0500, Marty wrote:
Richard Casady wrote:
Sounds like BS. My house barn and corn crib all had half inch or so
braided copper cable connecting 1/2 inch pointed rods. The ground rods
are presumed to be the standard ones the electrical places all sell.
They were struck hundreds of times, they were on top of a hill.
I heard it was 20 000 amps, at a million volts.
Guess I should have included a tongue and a cheek,,,
However my point was rather that lightening is inherently unpredictable.
Our barn is "protected" the same as yours, still has the cool glass
globes at the base of the pointed rods, what the hell they are supposed
to do I don't know. As far as I know it's never been hit. I've seen a
neighbor's lightening system vaporized, fortunately it was raining hard
enough, and his roof was leaky enough that damage was limited to a some
singed hay and a couple of scorched boards.
I've been involved with ground protection systems for airports,
(counterpoises in the trade) and seen some absolutely whacky things,
like edge lighting halogen bulbs blown up, even though the feeder was
buried three feet below a 4 gauge bare copper ground wire just a few
inches below ground..... I've seen constant current power supplies that
feed the lighting fried but the lighting fixtures and transformers
remain unharmed.... lighting is funny stuff..
Pretty much my take based on fairly extensive reading.
Think I came to the conclusion that:
Bonding can pretty much provide a safe area so long as you keep you
hands off metal.
An electrical disconnect that won't likely be jumped might be worth
exploring to cut down the expense of damaged electronics.
Basically like pulling the plugs in the house, which I usually do
during electrical storms.
Keep some portable radio/gps gear in an insulated container.
Since you might get holed, have a good collection of damage control
plugs.
Dry weather lightning can still catch you off-guard.
--Vic
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