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Re: [TowerTalk] Grounding base slab and pier tower bases

Subject: Re: [TowerTalk] Grounding base slab and pier tower bases
From: Roger D Johnson <>
Date: Tue, 04 Jul 2006 14:31:43 -0400
List-post: <>
David Robbins K1TTT wrote:
> 20' isn't all that much rebar.  There's probably that much in a 3'x3'x4'
> block for rohn 25/45 type base when its done right.  And I would be
> surprised if anyone could put such a limit on 'absorption' by a ufer ground
> like that, sounds like something pulled out of thin air to me.  The truth
> is, concrete is a pretty darn good conductor in its own right, especially in
> ground where it stays relatively moist.  The whole reason for concrete
> encased ground rods is to improve the conductivity and spread the current
> out more so that the current density is lower when it gets into the
> surrounding soil that is a worse conductor.

I really need to find Ufers paper on the subject. As I said originally,
my understanding is that the capacitance to grounds important to absorb
the charge which then leaks off through the concrete. You seem to be
treating it as a pure resistance. I have my doubts whether the average
tower base will carry 10-20 Kamps and, even if it does, it has to dump
that charge into the surrounding earth.

73, Roger

Remember the USS Liberty (AGTR-5)

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