Any Electrician's that can help.....

[W12GT]

I am having a house demolished and I need the head and meter moving. I have been tracing services with a CAT and genny and have found some issues. I was tracing an indicated power source in the driveway and it came back as 0.6m deep so I've dug it out in reddiness for temp supply and found a 15mm copper pipe which I believe is the water supply but it's giving off a power signal and genny reading when I clamp the incoming cable or put the genny over the outside stopcock. In the house I am finding power signals everywhere which is strange as I've disconnected all but one circuit from the dist board. So I've done some testing:-

241v line to earth.
241v neutral to line.
0v neutral to earth.

Getting a continuity reading between disconnected earth on distboard to earth clamp on incoming cable.
Continuity reading from incoming cable earth to incoming neutral (as expected)

I've then disconnected the last circuit, With all visible earth bonding removed and I am still getting a contuity signal from the neutral to my pipework - and still getting a power signal from all pipework including the copper pipe in my drive.

I've also noticed that with the 100Amp breaker off and all circuits off the meter wheel turns backwards very very slowly.

I've also found an indicated power cable running under part of the house into a property a couple of hundred metres behind - I think our supply branches off this and up to the head.

Any ideas on what could be causing the power readings down the copper pipework?

I am waiting on UKPN to come out and investigate - hopefully tomorrow but I'm interested to know possible causes.

Thanks in advance!

[speedyman]

Sounds like a floating earth fault. Theres a short somewhere and the earth path is not effective to ground.

[Jonesy23]

I have had something vaguely similar, the incoming water supply had volts on it from somewhere external and these could be measured on the earth circuit compared to true ground. Basically the earth bonding to the supply pipes pulled the earth circuit up and nothing locally was capable of pulling it down.

Never did find out where, the UKPN guys reckoned it the was a short somewhere to a water main and a pretty substantial one, but finding out where wouldn't be simple as it could be quite a distance away.

Certainly it was outside my supply connection and property as we did enough isolation on their side to prove it.

[W12GT]

Thanks all. The engineer came out and did a thorough test- supply is healthy and as it should be. The water pipe had no voltage detected on it - apparently it's very common for copper gas and water pipes to be detected as power when the pipework runs close to power cables as it can act as an antenna for the electromagnetic fields.

Happy days!

[Dave_ST220]

I've also noticed that with the 100Amp breaker off and all circuits off the meter wheel turns backwards very very slowly.

Hmmm. There is something not right there!!

[Simpo Two]

Dave_ST220 said:

I've also noticed that with the 100Amp breaker off and all circuits off the meter wheel turns backwards very very slowly.

Hmmm. There is something not right there!!

The water in the soil is making a battery with the copper pipe and making electricity...

[EireEng]

Dave_ST220 said:

I've also noticed that with the 100Amp breaker off and all circuits off the meter wheel turns backwards very very slowly.

Hmmm. There is something not right there!!

Do the numbers on the meter tick backwards too?

[Paul Drawmer]

Like this?
https://youtu.be/uPBNk2wIcTs

[W12GT]

No mine is very very slow - you wouldn't notice if you didn't study it. He didn't know why it was doing that but said it could be a faulty meter.

[Busterbulldog]

I recently got called out to a broken down boiler in a doctors surgery. I kept getting a tingle on the hairs on the back of my hands when I touched anything metal...eg radiators , boiler, sinks. My multimeter picked up mains voltage on everything it touched....it turns out the western power electricians had wrongly connected live to earth in a pole outside. So we had two lives coming in...seemed pretty dangerous to me. The workers begged me not to report them as it was a stackable mistake.