A strange one today, called to a house that had had its earth conductor pulled out by a dog.
A length of 16mm was lying on the floor, one end connected to the consumer unit.
I turned off the power, then reconnected it to the TN-S sheath clamp. But, on doing it, there was a tiny spark once connecting it. I did this a few times to see if it continued - it did. I didn't bother to take any voltage readings, but I did do a Ze, which gave a very reasonable 0.14 ohms.
Checking further, the cut out was a loop in system, whereby a 3 phase head supplied this house from one phase, and next door took another phase, along with a shared neutral.
I am presuming that next door have an earth problem, and are getting a good earth from the water pipe, and once the earth conductor from the head is reconnected, they have a better earth. The cable supplying the next door house does not export an earth, it looks like it is 2 core split concentric, so probably TT earthing next door, or , possibly TN-C-S, but the first house had no PME stickers, or combined E and N.
Should I inform the next door neighbours about this, and could it be a hazard to my customer?
