Date: Wed, 13 Oct 2010 22:08:11 +0000
From: Don Moman VE6JY <ve6jy.1@gmail.com>
Subject: Re: [TowerTalk] Protecting Buried Guy Anchors
If you have insulated guy wires, no galvanic current can flow. If not:
insulate them.... 1 amp for 1 year consumes 20 lbs of anchor - so even a
few milliamps over time from a small earth potential difference can weaken
your anchor. Protecting the anchor rod from the earth with tar/pitch
compound can't hurt either.
73 Don
VE6JY
On Wed, Oct 13, 2010 at 9:35 PM, Mark Robinson <markrob@mindspring.com>wrote:
> I have installed the standard Rohn GAC303 guys anchors into buried concrete
> per the Rohn drawings.
>
> I was talking to a tower installer who says that he has seen these buried
> guy anchors eaten away in only a few years.
I think that I am OK since I have pulled 8 foot copper ground rods that
> have
> been in the ground here for several years and they came out shiny and
> bright.
............................................................................................................................................
>
Interestingly enough, I will be adding cathodic protection to my 145 foot Rohn
45 tower this
weekend even though after 9 years, there is no evidence of anchor corrosion
(primarily because
my guys are insulated and not grounded at the anchor points).
GL es 73,
Jeff, W3KL
## what's wrong with grnding the guy wires themselves ? You see that in the
Rohn catalogs.
IF EHS used, and broken up with egg insulator's, there should be no current
flow. There was
something in the latest EIA-222-rev G spec abt grnd rods for guy wires. I
think it was that
copper rods could no longer be used, because of disimilar metals, or the grnd
wire from the
grnd rod to the galvanized guys could not be copper.
## it all depends if your soil is alkaline..or acidic. Around here, 8' copper
grnd rods last forever,
and ditto with copper water pipes coming into homes. Galvanized anything that
is in direct soil
contact just eats itself. A friend back in 1980, had a rental place, and
buried the bottom 2' of his
tower [angle legs] into dirt. Then guyed the tower, along with the house
bracket. He took it all down
in 1990....and there was almost nothing left of the tower that was buried in
the dirt ! Apparently, if using
galvanized GAC-XXX rods in buried concrete, the portion of the GAC-XXX rod
that comes up at an
angle is all in direct contact with the soil. That portion is supposed to be
covered with roofing tar pitch
1st, [ let harden].. then installed in the grnd. Having said that, telco's
and pwr co's use thousands of
buried rods in the grnd, [AB Chance type screw in anchors, installed with a
Kelly Bar] and they appear to
hold up for decades. They also use at least one egg on each guy wire too.
Jim VE7RF
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