Insulation resistance testing

[schoe]

Hi all ran a ring circuit for someone about 6 months ago and when I carried out the insulation test my results were around 250 m ohms for l-n and slightly lower for l-e, anyway didn't think anything of it as we had just plastered all the rooms where the ring circuit went.

Returned to the same job today and thought I'd just check it while I was there, anyway instead of the results rising which I would have hoped they have actually dropped to around 150 ohms still well within the requirements but it's dropped never the less.

I investigated further and split the ring circuit at the half way point and tested each way, in doing so I got results which were higher on both legs separately then when they were together.

Connected everything back up and re tested from the consumer unit and the results had lowered to 150 ohms again,


Has anyone come across this before? I don't think it can still be damp that is cause the results to decress , could it be a problem with one of the socket fronts that is causing the lowering reading?

thanks for the help in advance

Chris

 

[Octopus]

Seen this with sockets. Its over 2 meg so why worry!

 

[schoe]

It was just the fact that the result had lowered which I couldn't understand

 

[Richard Burns]

Had you tried keeping the test going and see if it rose steadily? in this case I would have thought it was damp in the fittings.

Someone could have poured juice over a socket the day before.
You may have had stronger batteries in your tester when you were testing today.

 

[schoe]

It was rising but very slowly, I'll have to monitor the situation thanks

 

[JIM4179]

A pain but you are well in, wouldnt mind betting that if you were to take all the sockets off and join the cables you would be clear

 

[Octopus]

A pain but you are well in, wouldnt mind betting that if you were to take all the sockets off and join the cables you would be clear

But with readings like this nobody in their right mind would waste their time doing that would they?

 

[somersetsparks]

you won't have to monitor it, there is nothing to monitor, I wouldn't waste another minute of the poor customers time!

 

[PEG]

Don't you listen to all those cynical,angry electricians :rolleyes2: If you have the time and patience to check and re-check those readings,fair play to you.I have done this for years with things like Ra readings,call it research,interest or devilment,but it is these things that build up your experience and keep you keen.Remember not to let BS7671 spoil any joy to be had from the job.