I don't recall seeing it anywhere, but is there any problem with using some
left over guy wire (3/16 EHS) to go from the tower to a ground rod at the
base of a tower. Planning on going to about 60 feet with Rohn 25 and will
probably use a ground rod at the tower and maybe one at each of the guy
points. Just seems to me that if the correct clamps are used the wires and
tower would be the same material and not have a galvonic reaction.

I'd avoid it. The conductivity of steel (stainless?) guy wire is much
lower than copper, maybe 40 times lower, so your 3/16th EHS is maybe
something like 20 gauge copper equivalent.

Dan

Ralph Mowery wrote:
I don't recall seeing it anywhere, but is there any problem with using some
left over guy wire (3/16 EHS) to go from the tower to a ground rod at the
base of a tower. Planning on going to about 60 feet with Rohn 25 and will
probably use a ground rod at the tower and maybe one at each of the guy
points. Just seems to me that if the correct clamps are used the wires and
tower would be the same material and not have a galvonic reaction.

On 1 Nov 2006 19:44:24 -0800, "
wrote:

I'd avoid it. The conductivity of steel (stainless?) guy wire is much
lower than copper, maybe 40 times lower, so your 3/16th EHS is maybe
something like 20 gauge copper equivalent.

3/16" is approximately 5 AWG. The ITT handbook gives the resistance
of copper-clad steel (a good enough approximation to zinc plated
steel) as about 1 ohm/1000'.

Compared to the resistance of a ground rod to Earth "connection" I
think that a few feet of steel wire resistance is in the noise.

I'd watch out for a zinc to copper connection tho.


Dan

Ralph Mowery wrote:
I don't recall seeing it anywhere, but is there any problem with using some
left over guy wire (3/16 EHS) to go from the tower to a ground rod at the
base of a tower. Planning on going to about 60 feet with Rohn 25 and will
probably use a ground rod at the tower and maybe one at each of the guy
points. Just seems to me that if the correct clamps are used the wires and
tower would be the same material and not have a galvonic reaction.

On Tue, 31 Oct 2006 23:45:05 GMT, "Ralph Mowery"
wrote:

I don't recall seeing it anywhere, but is there any problem with using some
left over guy wire (3/16 EHS) to go from the tower to a ground rod at the
base of a tower. Planning on going to about 60 feet with Rohn 25 and will
probably use a ground rod at the tower and maybe one at each of the guy
points. Just seems to me that if the correct clamps are used the wires and
tower would be the same material and not have a galvonic reaction.


Do you have codes or standards that provide guidance, or requirements?

The standard applicable here in Australia suggests that it is likely
that earthing conductors need to be 35mm^2 copper or better (~ 2AWG).

The conductor used for lightning protection should be sufficient to
carry the anticipated current without deterioration and without risk
of fire.

People often design for a scenario like 20kA for 0.1s.

I don't know how 3/16EHS performs in that scenario, but I venture that
it probably has csa of about 10mm^2, conductivity of a tenth of
copper, higher inductance than copper (which affects the voltage
rise), higher specific heat and higher melting point.

Perhaps it is safer to use copper of adequate size.

Owen
--

Compared to the resistance of a ground rod to Earth "connection" I
think that a few feet of steel wire resistance is in the noise.

But the power-handling capability of that wire is much less than that
of the earth below the tower ;-) It would be a tad better at not
exploding than a 20AWG wire would, because it's more massive, mostly,
but I don't know that I'd want to use it as a primary grounding
conductor anyway.

Dan