Have you talked to the water supplier and found out about the supply.?
So far we know that there has been an electrical problem (may still be) and obviously that should be corrected, but there doesn't seem to be any clear evidence relating the electrical installation to the demise of the pipes.
Does the water come from the mains or from a well?
Do the neighbours have the same issue with their pipes?
.andy
To email, substitute .nospam with .gl
Not after rectification of leakage currents by the copper oxide layer. See this first letter which I've just found.
Ah, I see what you're saying.....
Plausible I suppose.
.andy
To email, substitute .nospam with .gl
But the supply system here does appear to be PME, from the references to a 2-wire overhead line and a 0.2 ohm Zs value. That being the case there should be a number of other earth electrodes in parallel with the main transformer earthing, making it pretty hard, I'd have thought, for an consumer's earth fault to drag one phase down very far. Moreover such an earth fault would have to be to a local means of earthing (in a TT installation) and not to the CNE[1] conductor.
A broken supply neutral might be another possibility, but I think we can rule that out as there's been no mention of supply voltage problems.
*** *** ***On further reflection though, perhaps there's something in what you say: IF something is causing the potential of the CNE conductor (and therefore all the protective conductors in the house in question) to be well above earth, AND the water supply is from cast iron mains (clearly well earthed) THEN the said potential difference will appear across the section of plastic water mains feeding the property. This could cause electrolysis in the water and perhaps some of the strange effects described.
One thing that would certainly do this is if the overhead supply has been connected with reversed polarity, so that the consumer's PME terminal is actually connected to the phase! Hmm, yes, your suggestion of making voltage measurements to a local independent test earth electrode is a good one.
*** *** ***I would also like to point out that the OP, Keith, is the NE London Regional office contact[2] for a company whose business is gas and electricity safety inspection and testing.
[1] Combined neutral and earth. [2]
Yes, such a test should be done, but I doubt the earthing is all live: if it is the OP would have been bitten numerous times by now. Equipotential bonding would not stop that happening, it would merely reduce the number of opportunities for it. There are real life earths inside houses as well as supply provided ones.
NT
Must get my eyes tested, missed the decimal point in front of the 2 when I first read the OP! Mind you, all that proves is that the phase to neutral loop on the mains is sound, coz that's all the earth loop impedance tester is checking.
Not at all. The notional maximum value for additional electrodes is (or was - I've been out of the industry for a few years now) 40 ohms maximum, but they were rarely tested anyway. If the main earth for the transformer happened to have been broken with ploughing (and it happens).....
Not exactly a common occurence, but I came across two or three instances during my time, although the usual warning is reports of shocks in the property, or someone reporting that they're reading 300-400 volts from phase to a water pipe or similar.
Unfortunately we don't live in an ideal world where every electrical installation complies with the current edition of the regs - after all, the problem doesn't necessarily have to be in the property in question. There are countless voltage operated trips still in use - something of a contradiction in terms - and there will be many installations where the local water distribution system offers a better connection to the general mass of earth than the local REC's system. We also have the incompetent DIYer who carries out work without understanding the theory behind what he's doing, but that's altogether a different story.
At the moment, you are coming back with more and more questions and no factual information on which to make a judgement. I did note also the email addy you were using, and find myself wondering why the very firm you represent cannot do this work for you.
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