Bill Aycock wrote:
> Another myth:
>
> At 03:50 PM 8/25/98 -0700, you wrote:
> Also, don't be temped to put your grounding rods through the base. I
> >was originally planning to do this and found out that a lightening strike
> would
> >cause the concrete to explode, causing the tower to fall, etc.... >> KT3U
> >>
> >>
> I have heard this many times, but have never heard of a case being
> documented. The ARRL is one of the perpetuators of this, in their position
> against" "Ufer Grounds", but I dont know who, at ARRL, started it.
>
> If anyone knows of an authentic case of grounds through bases causing an
> explosion, please post to the list, giving traceable info.
>
> Remember- traceable, please. Second and third hand "my cousins dog groomer
> heard of---" are not real.
>
> Bill
I'm with Bill!
Anyone presenting evidence of a "Ufer" ground causing damage to a concrete
footing should provide the details of the installation. Putting 10' of #10 wire
doesn't get the job done!
The instructions for "Ufer" ground use are clearly defined in the Polyphaser
book, The "Grounds" for Lightning and EMP Protection. The "Ufer" ground is
intended to be used with a peripheral ground system. The size, and length in
the "Ufer" ground conductors, and their placement relative to the edges of the
footing are also described.
Poor installation practices result in failures!
I have only one source for empirical experience with the "Ufer" ground
technique. W7CY had 3 crankup towers at his old qth, here in Minden NV. All of
them, utilized only "Ufer" grounds, via approx 30' of #2 solid copper wire in
the tower footing. All towers took direct lightning hits and no gear was lost.
Coax leading into the shack was also protected with Polyphaser equipment.
I was there to see that concrete was not blasted across the county!
Those who want to explore the lightning protecting possibilities of the "Ufer"
grounding technique should get the Polyphaser book!
73, Kurt
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