|To:||"Charlie" <firstname.lastname@example.org>, "Bill Shell" <email@example.com>,"Tower Talk List" <firstname.lastname@example.org>|
|Subject:||Re: [TowerTalk] Conductive Concrete and Grounding|
|From:||"K8RI on Tower Talk" <email@example.com>|
|Date:||Wed, 26 Jan 2005 21:40:36 -0500|
The one thing predictable about lightning is its unpredictability.|
The Science (Discovery) channel had an interesting program on this a couple of weeks back.
Lightening varies greatly in strength from a direct strike to a 25 G might scorch a bit, or burn some insulation. Then it goes all the way up to the "super strikes" which they now believe are associated with "sprites".
Although lightning is DC (static electricity) is does tend to "ring" with a strike consisting of both positive and negative current flow.
The latest, or at least one of the latest theories is the super strikes are a downward current flow receiving power from sprites which cover a wide area. Strangely enough these are a higher percent of cold weather lightening than that associated with warm, or hot weather.
Supposedly the regular strikes of a strength that can be managed, while the super strikes are a tad beyond our abilities at present.
So, taking precautions should mitigate damage from the lesser strikes, but with the super strikes you can only hope for the best.
I've always heard even from lightning experts that there is little one can do to stop or even minimize the affects of a direct hit.My tower gets hit about 3 times a year. So far only one strike did any damage as far as I remember (one poly phasor and one computer) and I'd call that minimal. The old tower was only hit a couple of times over nearly 15 years, but those were memorable.
The last hit was the one where my neighbor was looking right at the tower when it was struck. No damage. The previous one caused the UPSs to complain and the network (CAT5e) reset, but again there was no damage. Had I not been setting here at the computer I would never have known the network reset.
BTW I use cordless keyboards and mice.
Roger Halstead (K8RI, EN73 & ARRL Life Member) N833R, World's Oldest Debonair (S# CD-2) www.rogerhalstead.com
Charlie Ham Radio - AD5TH www.ad5th.com Live Blues Music www.492acousticblues.com
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
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