Just an observation but as this problem would seem to be an earthing issue, I did a bit of checking today.....our CU would appear to be earthed via a large ground spike,earth cable runs from the CU through the wall of the house and is attatched by a clamp,like a car battery terminal, to the top of the spike.
Further investigation and I found that not only was the clamp a bit loose,I could turn it on the spike (now tightened)but I also I think if I tried I could pull the whole thing out of the ground,it's set in a concrete path to the side of the house,if I knew how to post a pic I would to show what I mean.
I guess over the years with expansion and movement, it's come loose. Could this be contributing to my problem?
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