On Mon, 23 Jan 2006 13:42:41 -0800, Richard Clark
wrote:

On Mon, 23 Jan 2006 20:54:19 GMT, Owen Duffy wrote:

Interestingly, I note the ref doc recommends galvanised electrodes. I
have been conducting an experiment here where I have recorded the
resistance of several driven earth electrodes over some years, and a
galvanised electrode of 25mm OD performs much worse than a copper clad
electrode of 13mm OD driven just 300mm away from it (both 2.4m long).
(The galvanised electrode is not electrically bonded to the earth
system for reasons of galvanic corrosion).


Hi Owen,

What method did you use to measure the resistance?

I used a Kyoritsu instrument designed for the purpose. It uses the
three wire fall of potential method, and makes its measurements using
an AC waveform of about 800Hz.

Owen
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