I have used many types of Copperweld in my consulting business. A couple of
times I have called their engineering staff about products.
One time I asked about the aluminum on steel product, which I believe was
called "aluminumweld." (Not to be confused with aluminum arc-welding wire)
I was told if the wire was used on ground or buried I would have dust in a
year or two.
This has to do with dissimilar metal action in the presence of an
electrolyte.
Here, in New England that electrolyte can be supplied by acid rain,
fertilizer, salt air (near the coast), or salt from plowing snow. Locally
the City Fathers have decided that plowing with salt during smaller snow
storms is less expensive, for them, then using an actual plow.
Here the action of aluminum can often be seen on pick-up trucks and vans
where an aluminum "running board," or step has been installed. After a few
years, fair sized spots of rust develop where the step is attached. A few
more years results in holes.
Wikipedia has a nice page that discusses dissimilar metals. Essentially the
two metals and electrolyte makes a battery, that has a short-circuit. The
"trick" to using dissimilar metals is to pick two that are close on the
voltage scale.
Like copper and steel.
The other thing to look at is the thickness of the copper on copperweld.
The company uses a conductivity scale to describe thickness, measured at 60
Hz. Very different at 1.8 MHz.
In the past I recall they had a different scale where I calculated that
their 30% conductivity for something like #10 wire was adequate. But memory
slips with age.
I do remember you will need to be careful with "copper coated" wire. A very
thin plating does you no good at all, you are using steel with it's poor
conductivity. Around 3% of copper, if memory serves me.
Pure aluminum wore is just fine. You should use a larger size than copper
for two reasons: strength, and conductivity. Aluminum is roughly 50% that
of copper.
I would keep aluminum from the ground, tho.
Jim, W1EQO
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