Insulation Resistence on ring main

Dannydigger · Jul 22, 2015

Hi Guys,

I am absolutely baffled at the moment as to why i cannot get the correct reading for insulation resistence when Im testing the line/neutral on the ring main. I have made sure everything is unplugged, disconnected the neutral from the bar and allgator clipped to my test lead. When I press test, it goes through the relevent steps and comes back with 0.00

I have also tried this on my ring main at home and still get the same reading for line/neutral.

I get >1000 when I do CPC/Neutral and all other Circuits give correct readings of >1000

Its just the Line/Neutral that is stumping me, any help is greatly appreciated

HandySparks · Jul 23, 2015

Dannydigger said:
My apologies MDJ and also for my outburst. I was getting 0.00 so all neons were off. I have double checked myself now and found a fridge plugged in at the back of a cupboard. My customer had just turned it off by the FCU on the kitchen top.

thanks again folks

If the FCU supplying the fridge was switched off, then the fridge will not have had any effect on a L to N IR measurement unless the FCU was faulty.

yellowvanman · Jul 23, 2015

ian.settle1 said:
Please explain why you are not obliged to test it?

As with everything its up to the person doing the testing as to what they test, and this thread has highlighted a typical problem with testing between L-N. The priority is to ensure that a fault to earth is picked up, hence a lot of people short L/N together and test to earth, as quoted in:

Guidance Note 3 - 3.10.3
'There is a range of possible outcomes when carrying out insulation testing. Tests are typically made between all live conductors connected together and earth at a test volatge of 500V d.c.'

Yorkshire · Jul 23, 2015

Check for spurs outside sockets and spurs got a kickboard heater in kitchen? Hob spark extractor hood hidden sockets in cupboards hell even in the loft theres a load on it somewhere if theres a short on it