120V from water tap to true earth

[LastManOnline]

My question, could a poor earth connection, cause a potential between earth and true earth?

Yes it could.And modern appliances with their built in electronics will quickly alert you to your poor earth as soon as you are unfortunate enough to make contact with the affected metal while standing on a poorly insulated floor or worse while simultaneously touching other metal that is well earthed/bonded.

 

[Midwest]

Yes it could.And modern appliances with their built in electronics will quickly alert you to your poor earth as soon as you are unfortunate enough to make contact with the affected metal while standing on a poorly insulated floor or worse while simultaneously touching other metal that is well earthed/bonded.

Would it reach 120V though?

 

[LastManOnline]

Would it reach 120V though?

Good question.I personally never measured a voltage that high that resulted from a disconnected CPC on a circuit containing appliances with intentional leakage built in.

Looking at the problem from another angle ,it would appear that the homeowner solved the issue by reconnecting an earth wire that had become loose.Is it possible he has been using an earth wire as a return wire? (As a neutral).The disconnected earth wire would then act as a "broken neutral" causing a voltage to appear on it.

 

[James]

In the U.K. a broken N will rise to 230v if there is any load on the circuit after the break.

 

[Vortigern]

Errmm can a load be on the circuit after the break, it would be dead from the break onward??? When I started learning it was Live and Neutral, and then of course earth which was really just another neutral. Then I was told, there is no neutral now, it is all phase right the way back to the star point. Okayyyy, I took that on board then understood that a broken neutral is live. Well of course it is because in truth, it is all phase. With me so far?

 

[LastManOnline]

In the U.K. a broken N will rise to 230v if there is any load on the circuit after the break.

Correct.But in the case of the OP where it appears some unconventional electrics has been carried out I,m wondering how could reconnecting an earth possibly lead to the voltage on earthed metalwork been removed?The only examples I can come up with are..

1) intentional earth leakage belonging to the affected circuit.

2) The earth wire has been used as a return wire and is now in effect " a broken neutral" .However as it's an earth wire it may be connected with other metalwork that offer some alternative but high resistance paths to ground.This would cause a volt drop.Entirely speculation on my part

 

[Midwest]

Firstly I must add, I cannot be certain the electrical additions have been carried out by my neighbours or anyone not competent. Also the main supply has been verified as in order by the DNO.

Therefore the fault was somewherein the property, could of been in the addition or possibly in the existing, although you’d of thought that would of been found by the original EIC, but you never know.

Neighbours appear to have gone away for the weekend, so been unable to offer Zs test at pod. Her indoors is saying not to get involved. I’ll see, and perhaps pick my moment. But he is a bit of a very confident type, if you get my drift.

 

[LastManOnline]

I

Neighbours appear to have gone away for the weekend, so been unable to offer Zs test at pod.

I, m progressive leaning towards the possibility there is actually nothing wrong and you could end up trying to fix something that is, nt broken.
The DNO found nothing wrong with the supply or the earthing.
They isolated the problem to the ring.
The issue was solved when the loose earth was reconnected.

Where does that leave us?
Neither the homeowner nor yourself mentioned that any appliances had stopped working,which confirms the integrity of Land N and rules out one of my previous suggestions about the earth been used as a, return wire.
That brings us back to intentional earth leakage from one (or more) of the appliances.The circuit for this current has now been opened, creating a "broken neutral" type scenario. This voltage will appear on all class 1 appliances and metalwork connected to them on the affected part of the circuit.

The above is easily established by plugging out all appliances and isolating all fixing appliances on the ring. Disconnect the earth that caused the initial problem. Test at the tap and it should be volt free. Plug the appliances back in progressively, testing as you go and you should find the 120 volts reappearing on the tap.

I have experienced the above problem on several occasions