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.

 

[JD6400]

Or it could be the poxy volt stick and nothing is wrong !
Would trust Tony Blair more than one of them , if you ask me they are both the devils work !
Once you have checked with a proper piece of equipment ! I would then start looking for a fault if there is one .
Heres hoping it's just one of merlin's wands jumping at it's own Shadow again , i suppose thats better than not bothering at all there again , as usually is the case !
And you get a early knock off , anyway which ever it is good luck mate !


PS . Don't know if you noticed but i ain't that keen on volt sticks !

 

[topquark]

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?

The bit you're missing is that this is a fault scenario, so not in the event that the short is a full short, then it will be at, or very close to, zero. It will probably be hovering somewhere between nominal 230 (238 or so) and zero. Perhaps a better way of phrasing it would have been that you MAY see that fault PD reflected back at the CU (by a reduction in the normal PD between line/neutral). Hope that helps.

 

[MarkieSparkie]

I thought I would tell you about a commercial office block where the office staff and visitors were complaining about receiving electric shocks from certain radiators in the building. After exhaustive electrical testing, I could find nothing wrong with the installation and was just walking back to the client to give her my ‘good’ news. As I passed a radiator I too was zapped on my bare arms, ‘luckily’ I saw the flash as it happened and it gave me a clue to the cause. To cut a long story short, I found that the radiators that were causing the shocks were all ones where the valves to the radiators had there threads heavily bound with PTFE tape and that the most complained about radiators were mounted on internal plasterboard stud walls. The PTFE tape was insulating the radiators in question from the pipe work and the passage of water through the radiator would charge the radiator over time, as if it were a crude but effective capacitor. The charge would continue building until somebody walked passed close enough to create a ‘static’ discharge path. The victim was usually female, we subsequently found that their shoe soles, on average, were less than half as effective as insulators as those worn by their male colleagues. The company approved supplementary bonding each radiator to the adjacent pipe work, eliminating the problem.

 

[MarkieSparkie]

Reversal of fortune?

In a more recent domestic job, I came across almost the reverse scenario. The client complained that they regularly got electric shocks from the radiators. On investigation, it again seemed that the electrical installation was blameless, even the radiators and all visible pipe work was well bonded back to MET and that soundly earthed. When talking to the client again later, she said “… first noticed in early autumn before we needed to use the central heating, just after we had the house re-carpeted throughout.” This was the clue I was searching for, the carpets fitted were of very durable nylon berber-twist that was popular at the time. As the family walked over the carpet they became statically charged, literally charged bodies. When passing the good earth path presented by a radiator the charge would leap from one to the other giving the appearance that the radiator was shocking the individual. After some research I was able to recommend periodically treating the carpets with a 3M product which reduced the static build-up and solved the problem.

 

[JD6400]

Hi Markiesparkie


I like to believe that DP Elec has never left a job with any type of fault unsolved .
But hats off to you !!!