Hans is right.
You need an intermediate metal for washer, lugs , or other hardware.
If your installation is only for Field Day, or a few months/years, it
probably doesn't matter. If you want your installation to be "forever", then
this stuff has some bearing.
In the long term if you have dissimilar metals (eg galvanized/iron/steel
mixed with copper/brass) you will sooner or later have battery effect
(galvanic action). Depends on pH of all materials, moisture, etc. I don't
have much expertise in the chemical arena, and we need our C.E.'s to weigh
in.
One tip I was given is to use a "mediator" metal to join two reactive
dissimilar metals (similar to "sacrificial anode").
In many cases this means joining
a) Galvanized steel tower
b) Copper/brass wires/clamps/rods
The trick I learned (unconfirmed but maybe True?) is to use STAINLESS STEEL
hardware (someone else said lead, also fairly non-reactive) to keep the
iron/steel separate from copper.
So:
Galvanized steel tower legs to
Galvanized tower base to rebar, concrete, whatever
Big galvanized tower bolt thru base with galvanized lock washer & nuts on
the other side
For grounding, a number of big fat 2"+ diameter stainless steel washers on
other side, enclosing copper ground wire which ONLY touches & is bonded to
the stainless (might require copper lugs, etc.). While all metals are at 0
ohms what we are looking at differences in metals
Key issue to keep copper ground wire 100% in contact with the stainless
steel, but no other metals, not soil, not concrete, etc.
If you can achieve this (not easy) you will have minimal (but not zero)
etching of metals
Not sure this makes sense, but it's what I now do and so far seems to work
well.
73
dan
k0dan
-----Original Message-----
From: Hans Hammarquist
Sent: June 20, 2013 17:09
To: towertalk@contesting.com
Subject: [TowerTalk] Fwd: Fwd: Screw Anchor Experience
To connect an anchor to a copper ground rod is an absolute no-no. That will
"eat" the anchor in no time.
Old wisdom (my grandfather, that was a blacksmith) to me to use a lead
washer to minimize electrolytic corrosion. I put small pieces of insulators
between the anchor rods and the turnbuckles to interrupt possible current.
Could not harm, I believe.
Hans - N2JFS
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