Re: Rock salt and RF grounds (fwd)

---------- Forwarded message ----------
Date: Tue, 14 Jul 1998 19:16:52 -0700
From: Scott MacGregor <smacgregor-at-aasp-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Rock salt and RF grounds (fwd)

Tesla List wrote:
> ---------- 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.
> --
> -GL
> www.lod-dot-org


This number (0.44ohms)conforms well with TCI (Cablevision) corporate
standards. For lightning protection and safety, all earth station and
tower grounds are tested every 6 months and must meet a <1 ohm standard. 

Scott MacGregor EES,Co.
Enterprise Engineering Services Co.
E-mail smacgregor-at-aasp-dot-net
Member: Cable Television Advisory Committee, Plainville, MA