On Fri, 14 Sep 2007 09:49:13 -0400, Jim Jarvis wrote:
>Everyting I've read says...provide a low impedance path AROUND the
>foundation, not through it.
Yes. If you study the literature on Ufer grounds, you'll see exactly
this comment -- that care must be taken to insure that a lightning
discharge through a Ufer ground does not compromise structural
integrity. I included such a comment in my Power and Grounding
"White Paper" for audio and video professionals. (on my website).
By virtue of its conductivity, a concrete tower base (or the
foundation of a building) will be grounded, and if the tower is
bolted to it (as it normally would be), it WILL act as a Ufer
ground, whether we like it or not. This makes it even more important
to provide multiple low impedance paths to earth around the tower to
divert as much of that current as possible.
Jim Brown K9YC
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