Live Rads?

[grumpy17]

Hi, Think i'llneed some helpful advise before attending this one. Got a call from a landlord who owns one of two purpose built flats on the ground floor.The gas board were in the flat upstair and put their voltmeter stick as a matter of course on the rads and pipework in the kitchen.It gave a live signal to indicate the presence of a voltage (dont know how much yet).To cut a long story short when the lighting circuit in the flat downstairs is turned off the volt reading stops. The central heating was added about 2 years ago to the upstairs flat. Anyone come across this before? Also not sure of my obligations if i attend as the tenant downstairs has turned the circuit back on saying they arent doing without light etc as its not their fault.Could plumbers who installed the system be responsible. I would have thought the 2 flats could not be linked in anyway.Apparently with the power back one you can touch the rads without getting a shock. I could be walking into a nightmare here but would appreciate some advise.

 

[londonlec]

I'd be pushing a long screwdriver into the lawn, and wander lead onto the metal work.

Possibly open junction box under the floor touching copper pipe, with no suitable main bonding.

I saw this before and it was a faulty cooker with no main bonding.

 

[topquark]

You'll be looking to isolate it to a faulty circuit (or circuits) first.

One method: Isolate each circuit in turn (after checking with the owner of course) and check again after each circuit disengaged. That will hopefully identify the faulty circuit, worst case could be more than one. Then do standard tests for the circuit(s) found to be faulty and diagnose as normal.

You may find that there's a PD at the CU between line and earth, if there isn't then either the rads are at (or around) 230V as well or the rads aren't bonded back to the CU.

EDIT: and be careful, you're not dealing with a normal environment, so take nothing for granted!

 

[pushrod]

Hi, Think i'llneed some helpful advise before attending this one. Got a call from a landlord who owns one of two purpose built flats on the ground floor.The gas board were in the flat upstair and put their voltmeter stick as a matter of course on the rads and pipework in the kitchen.It gave a live signal to indicate the presence of a voltage (dont know how much yet).To cut a long story short when the lighting circuit in the flat downstairs is turned off the volt reading stops. The central heating was added about 2 years ago to the upstairs flat. Anyone come across this before? Also not sure of my obligations if i attend as the tenant downstairs has turned the circuit back on saying they arent doing without light etc as its not their fault.Could plumbers who installed the system be responsible. I would have thought the 2 flats could not be linked in anyway.Apparently with the power back one you can touch the rads without getting a shock. I could be walking into a nightmare here but would appreciate some advise.

Yes with your rubber soled shoes on, but it they are touching another conductor at the same time it could be a completely different story. I would be very careful with this one and leave yourself plenty of time to sort it. Logical approach and proper testing on all suspect circuits .

 

[Electricalserv]

Well from what you have said, seems to be that lighting circuit. Obviously do the relevant checks but if voltage disapears after circuit is isolated..its going to be just that.

 

[Deleted member 9648]

Make sure all earthing and bonding is in place before calling the job ok after the cause has been rectified.....if they wont pay for that if needed issue an electrical danger notice and walk away......you have to cover your rear if the problem resurfaces and someone gets a belt.

 

[topquark]

One after thought, given that it's flats don't be surprised if the voltage doesn't disappear completly on isolating all the circuits in the flat (it could be that the fault(s) also extend into the other flat).

 

[VoltzElectrical]

You'll be looking to isolate it to a faulty circuit (or circuits) first.

One method: Isolate each circuit in turn (after checking with the owner of course) and check again after each circuit disengaged. That will hopefully identify the faulty circuit, worst case could be more than one. Then do standard tests for the circuit(s) found to be faulty and diagnose as normal.

You may find that there's a PD at the CU between line and earth, if there isn't then either the rads are at (or around) 230V as well or the rads aren't bonded back to the CU.

EDIT: and be careful, you're not dealing with a normal environment, so take nothing for granted!

I would hope that there IS a potential difference between line and earth at the consumer unit, or am I getting the wrong end of the stick?

 

[telectrix]

guess would be plumbers damaged cable then sat a copper pipe on it.

 

[Andyfm]

Or it could be that the voltstick is picking up an induced voltage - I know the kew technik versions do on cables sometimes, maybe the pipework is run through a bunch of cables.
I also remember, probably 8-9 months ago I was called to check a similar problem after a BG engineer picked up a voltage between the copper gas pipe and the incoming gas main when changing the meter, and shut off the gas. I called round and could not find any voltage on the pipework and all the main bonding was intact with all good readings, I told the landlord to get back in touch with BG and demand an explanation and reinstatement of the gas supply. I dont know if their external pipework was bringing a voltage into the building from the street outside or their electrical department was fishing for work? I didn`t hear any more.