On 12/30/12 10:33 AM, Michael Mraz wrote:
My dear old SK friend Al Caplan, who used to manage the Hy-Gain amateur
division when it was part of Telex, was emphatic about proper grounding
when I bought my HG-52 crankup. He said that lightning could split the
concrete around the re-bar if the tower took a direct strike. It was a
long time ago, but my recollection was that this nasty event actually
occurred to some unfortunate ham who had to abandon the old foundation
and install a new one in a different location.
this anecdote and ones similar come up all the time. The short answer
is, "not if the system was properly constructed in the first place".
If the rebar penetration of the concrete surface is incorrectly done,
then it's a problem. For instance, if the top of the concrete holds
water at the steel/concrete join, it will eventually wind up inside a
tiny crack, which then causes corrosion of the iron. That in
combination with water in the crack will cause spalling or cracking when
lightning heats it up.
And when discussing "well, what it the installation isn't done right,
then disaster strikes"... I'd contend that the odds of getting a Ufer
done right are a whole lot higher than some of the bolt on clamp and
grounding rod schemes I've seen over the years.
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