[TowerTalk] Conductive Concrete and Grounding

[K8RI on Tower Talk]

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
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>
>
>
> ----- Original Message ----- 
> From: "Bill Shell" <n6ws at charter.net>
> To: "Tower Talk List" <towertalk at contesting.com>
> Sent: Wednesday, January 26, 2005 7:36 PM
> Subject: Re: [TowerTalk] Conductive Concrete and Grounding
>
>
>> In 1966, I lost a tower to a lightning strike.  The tower was a 50ft Rohn 
>> 25 with three sets of two guys.  The tower was grounded an the base with 
>> ground rods and heavy guage wire going up about 3-4 ft where it attached 
>> to the tower legs.  Unfortunately, the strike went down one of the guys, 
>> over or through the heavy-duty egg insulators to the guy anchor where it 
>> cracked the cement open.  The tower, having lost the anchor point for one 
>> set of guys, just tipped over into my neighbors yard.
>> I didn't have any grounds on the guy anchor points.  I had thought there 
>> was no need, since the guys were broken at several points with egg 
>> insulators.  I was wrong.  Lightning is too unpredictable to follow 
>> rules.
>>
>> 73, Bill
>> N6WS
>>
>>
>> _______________________________________________
>>
>> 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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>
>
> _______________________________________________
>
> 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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>