[TowerTalk] RE: Concrete an insulator???

[w8ji.tom]

Hi Peter,

Peter, I'm very sorry you were targeted with nasty insulting comments. Even
if you were wrong, you never deserved to be insulted that way. The tragedy
is you were not wrong. 

As you pointed out, using a dc low voltage ohm meter to check ground
resistance in the presence of galvanic or induced potentials is a bad idea.
Someone else suggested reversing the probes and finding average resistance,
that is workable so long as the junction is linear and the meter stays in
range.

An AC ohm meter, especially a high voltage AC ohm meter, is a better
instrument for measuring dc resistance.

I think a ground rod in the middle of that concrete is a bad idea, however.
I remember how a concrete pier at WAAM shattered when the ground straps
were removed (an AM BC tower) for "maintenance" (waterproofing the pier so
freezing weather wouldn't work on the surface of the concrete). That day, a
thunderstorm hit. The lightning apparently found a path to the rebar just
under the surface and superheated the moisture in the concrete, chunks
wound up twenty feet away!

50 years of freezing and thawing wouldn't have tore it up that bad! 

73 Tom

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