DIYbanter - View Single Post - Question about earth rods and desired impedance

alan_m

On 19/07/2019 15:55, wrote:

Initially it made little difference, down to about 50 ohms, but after a
few days the resistance between the MET and the new rod had dropped to
less than an ohm (measured using PSU and ammeter and also by DMM). I
don't understand why it changed, but the new figure has been stable for
a week or so - it's possible that I had a bad contact before, but I'm
confident that I didn't.

When you first hammered the rod into the clay there was probably some
sideways movement making the hole a larger diameter than the rod. The
rod was only making good contact at the far end. Since than the clay has
flowed back to fill the void between the rod and the original side of
the hole.

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