Re: Rock salt and RF grounds (fwd)

---------- Forwarded message ----------
Date: Tue, 14 Jul 1998 15:31:14 -0700
From: lod-at-pacbell-dot-net
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Rock salt and RF grounds (fwd)

Tesla List wrote:

> > The other day I talked to someone in the national guard. He said that when
> > they install a ground rod they always pour rock salt (Ice cream salt) in
> > and around the hole. Anyone ever heard of this?
> Adding a conductive substance to the dirt around the ground rod is a
> well known technique. I've also seen copper sulfate used. The problem
> with salts in general is that they eventually leach out of the ground
> rod zone.  You need to keep dumping the salt solution on the ground rod
> area to keep the conductivity low.
> Somewhere, I saw mention of using carbon black as an additive to
> increase the soil conductivity. This might work better.  The idea is to
> (from an electrical standpoint) make the ground rod look bigger (larger
> in diameter mostly), so that its inductance is lower, and therefore the
> induced voltage from a lightning strike is reduced.

On Electrum we packed each of the 8 ground radials with 
Bentonite clay, which is somewhat conductive and harbors
moisture around the radial element.  The total R to the 
earth for this array was measured at 0.44 ohm, and seems 
to hold up well.