Insulation resistance test on ring final circuit

[Cj92]

I havnt done this test for a while and I am a bit rusty I was at a house and the breaker for the sockets kept blowing, I checked all the sockets and seemed sound no deterioration among the cables or loose connections etc. So I done a continuity test on the circuit l-l n-n e-e and came back fine but when I came to the IR test one leg (L-N) was only reading 0.003 M and the other leg was clear. I didnt get to test at the sockets as I didnt have time but would this mean up to a certain point the cable has deteriorated and there after is fine or am I forgetting something.

Cheers 

 

[ProDave]

And what about L-E and N-E?

There is obviously a fault OR a faulty appliance plugged in. Further investigating needed.

Ask the usual question. Has there been ANY work done recently, yes that means ANY.

 

[binky]

that would trip the MCB, now you have to find where the fault is, which is simple enough. Can I ask if you are a qualified electrician or not? I ask becuse it will help us help you.

 

[Andy™]

that would trip the MCB, now you have to find where the fault is, which is simple enough. Can I ask if you are a qualified electrician or not? I ask becuse it will help us help you.

nope. 0.003 meg is 3000 ohms... about 0.08 amps...

 

[Sharpend]

Isn’t 0.003 something like a neon across L-N? 

As Dave has said what was the other readings? 

 

[Cj92]

Hi sorry the other readings were fine just L-N and there no neons on the circuit there was only 6 sockets on the circuit with everything unplugged

And no work has been done recently 

 

[Sharpend]

Could there have been any fused spurs, perhaps in loft? Above cupboards? Etc 

 

[Murdoch]

I’m a bit lost .. you outline testing 2 legs after confirming continuity.

so are you saying one pair at the CU was good, and one leg was giving the very low IR?

if so, that doesn’t make sense. 

With only 6 sockets , you should really test L-N, L-E, N-E ..... at 500v to get the real picture.

then split the ring at one of sockets and repeat ....

 

[ProDave]

If you are SURE there are only 6 sockets, then remove them all split the ring and test all 7 legs of the ring on their own.

Re "no work done "  the reason I say ask and ask again, the last similar fault I had was a short in a cable above the kitchen ceiling.  Only THEN did the owner say "well we did just have the flat roof re done".......

That's why I say ANY work, not necesarilly electrical work.

 

[binky]

nope. 0.003 meg is 3000 ohms... about 0.08 amps...

 true, but a reading like that is more likely as low as the test gear will register (at least it is with mine) and could just be not very good test lead contact, leads not zeroed porperly etc etc.

 

[Cj92]

Yes Murdoch that's right one leg was good and the other low. I thought it was a bit weird to.

Dave: Well the guy showed me all the sockets and he said his pretty sure that's all if them I am going back later this week I may have to go hunting for an hidden socket if not I'll split the ring.

 

[Murdoch]

What were the end to end readings of the l, n & e?