Confusing earthing issue

[J_T]

Ok. I got a lend of a fluke tester.
I plugged in at a plug socket and carried out the loop impedance test (no trip) option. This gave a result of 1.5 ohms which doesnt sound right for tt. It also line up with the assumption that thete is a neutral earth fault somewhere.
I discinnected the outside lights. No difference then continued to disconnect circuits and perform the test untill i seen a different reading for a lighting radial... which was Err5.
I put my normal fluke multi meter across neutral and earth and measured 0.9ohms. I then disconnected the earths at different celing roses until i identified the fault (in the most awkward and out of reach fitting possible).
When i took the light fitting off the resistance went high (>1M).
I tightened up the wiring in the fitting (which is metal and earthed) and reconnected.
Everything seems ok now with the rcd tripping when tested and staying on when reset.
I think the Err5 is when you try and test with a load connected...
I didnt today but will do an insutalion test tomorrow to make sure there are no earth faults but hopefully that was the issue.
Does what im saying sound sensible?

 

[J_T]

Ok. I got a lend of a fluke tester.
I plugged in at a plug socket and carried out the loop impedance test (no trip) option. This gave a result of 1.5 ohms which doesnt sound right for tt. It also line up with the assumption that thete is a neutral earth fault somewhere.
I discinnected the outside lights. No difference then continued to disconnect circuits and perform the test untill i seen a different reading for a lighting radial... which was Err5.
I put my normal fluke multi meter across neutral and earth and measured 0.9ohms. I then disconnected the earths at different celing roses until i identified the fault (in the most awkward and out of reach fitting possible).
When i took the light fitting off the resistance went high (>1M).
I tightened up the wiring in the fitting (which is metal and earthed) and reconnected.
Everything seems ok now with the rcd tripping when tested and staying on when reset.
I think the Err5 is when you try and test with a load connected...
I didnt today but will do an insutalion test tomorrow to make sure there are no earth faults but hopefully that was the issue.
Does what im saying sound sensible?

 

[Octopus]

Seeing as this has been going on for nearly 1 year, would it be worth getting a decent spark involved who knows what they are doing ?

 

[J_T]

I appreciate it has been going on for a year but there have been 2 different faults here. Neither of which are run of the mill and 1 which required the suppliers intervention which is not always quick.
I was under the impression this was a forum for discussion/advice but if the advice is get an electrician i could have came to that conclusion myself rather than trying to understand the issue myself.

 

[Lucien Nunes]

Yes it does sound like the explanation, as per my previous post. Either your previous IR test was in error or quite possibly the fault was intermittent. E.g. when you took the IR test it was not quite in contact but by the time you were delving deeper into the Zs it had made contact. These things can be a royal pain to find, which serves as a reminder not to trust anything, anywhere. If I get conflicting or confusing results I always go back and recheck all measurements with extra care, avoiding the assumption that what seemed to be decent IR readings at the time remove all suspicion from the insulation as the culprit.

 

[Midwest]

Friggin MFT's. Whilst checking for extraneous pipework in bathroom today, I connect mine to a piece of copper pipe in a plasterboard wall, devoid of anything electrical and not physically connected to anything, just for the hell of it. Meter told me to pee off 'cos there was < 50v there

 

[UKMeterman]

Less than 50 volts? Check your symbols. But if you do find stray volts an insulation test might be a good idea.

 

[Midwest]

Less than 50 volts? Check your symbols. But if you do find stray volts an insulation test might be a good idea.

Apologies >50V