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[TowerTalk] concrete and lightning

Subject: [TowerTalk] concrete and lightning
Date: Thu, 27 Jan 2005 15:19:22 +0000
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I was responsible for a 500' self supported installation,
AM/FM/commercial tenants,  and significant effort was placed on routing strike 
current away from the foundation
concrete.   That stick gets hit 8-10 times a year, with no
damage, and it's been up since 1979.  

The polyphaser site indicates that concrete will absorb moisture, and release 
it slowly.   Depending on whether there is a good conductive path through the 
concrete... j bolts or welded rebar might get current to ground 
that way...or, if the cage system doesn't touch earth below th e foundation,  
strike current would have to flow through the concrete alone...producing added 

While no one can say for sure what will happen, were it my tower, I'd have 3" 
strap routed from the tower legs to a dissipative ground, above and around the 
foundation, and then a radial/strap/groundrod system beyond that.

This is particularly true if I had a fixed height tower attached to my home.  
I'd want to provide a nice, low impedance path the other way.    Personal 
preference at present is for crankup poles that live down.   Let the trees take 
the big hits.  


See:  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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