[TowerTalk] Ground Rods

[Eric Gustafson]

>Reply-To: <radioman@communique.net>
>From: "Glenn J. Torres" <radioman@communique.net>
>
>What about using stainless steel ground rods? Does anyone have
>any experiences or opinions on the use of stainless steel ground
>rods?
>
>73,
>
>GLENN J. TORRES
>KB5AYO
>

I have used them on occasion.  The only real caveat is to be SURE
that the stainless alloy you have is really completely stainless
(usually pretty soft stuff).  There are "stainless" alloys that
realy aren't really very corrosion resistant.

Usually, the reason we used stainless was that the customer had
plenty of thickwall stainless tubing scrap left over from
building or upgrading an ore processing plant.  As far as
survivability below grade, they seem to be fine.  Our problem was
getting bonded connections to them.  If you plan to use
stainless, and you will be using clamped connections, I'd
recommend that you arrange for all the clamped connections to
either be above grade or in a small ceramic pipe "well" where
they can be uncovered and inspected occasionally.  The oldest
ones we have appear to be just fine after 8 years.  I'm sorry
that I don't have any older ones to refer to.

Normally, when we don't have an extremely cheap (free) supply of
stainless pipe, we (pretty much regardles of soil pH) have the
best longevity when we use copper.  Not copper clad steel but
solid copper wire.  We usually place them by drilling an 8 inch
diameter 12 foot deep hole, backfilling the bottom 18 inches of
hole with gravel, placing one or two sections of "00" seven
strand bare copper bonding cable down in the middle of the hole
and backfilling the rest of the way with bentonite clay or a
substitute electrolyte carrier.

During relocation of a repeater site we have pulled some of these
copper earth terminals out after many years in place.  They
always look like they have an additional 60 to 100 years or so of
useful life left in them.  You could do the same thing with large
copper pipe.  We use the bonding cable because we already have
the cadweld molds and charges for welding the connections.

There are several companies making "active" grounding systems
which are stainless steel based.  These are all designed to
maintain chemical conductivity enhancement concentrations by slow
release of the chemicals.  They are quite expensive and not
required except in extremely poor earth conditions.  I don't
think you would really be interested in any of these.

73, Eric  N7CL

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