Insulation resistance

[ogosh289]

Hi all,

I've recently done the vrq level 2 and 2381 and have my assessment with Elecsa
in a few weeks. As I don't have a lot of experience with electrics I thought I'd
carry out some testing at home. When carrying out an insulation resistance test
(using a Mega 1553) on a ring final circuit i couldn't get a reading between
R1 + Rn. R1 + R2 & R2 + Rn both gave good readings >299M ohms. Previous continuity tests and polarity results were all good. I have removed every socket on the circuit and remade the connections, my next step will be to check the wiring between each socket back to the distribution board.
In my inexperience could I be missing something really simple? There are no Neons or anything else I can think of that may interfere with the readings.

Any advice would be greatly appreciated.

Regards,

Ogosh289

 

[malcolmsanford]

First off it's only continuity for R1 etc, for IR testing it's back to LINE/NEUTRAL/EARTH. What your saying that after the correct results for continuity and polarity you could not get a IR reading on the LINE/NEUTRAL. You did though get results on LINE/EARTH and NEUTRAL/EARTH.

IMO only one of two things can have happened

1) There as been a break in the cable between LINE/NEUTRAL since you did continuity test. But as you have said you checked the connections at each socket then that seems ok

2) You somehow did the LINE/NEUTRAL test wrong.

What I would do is find the first socket and disconnect it. Then find the leg that went back to the CU and IR test that. If you have it there then it is a case of going along the ring testing each point.

 

[pushrod]

In addition to what malcolm has said i would have a really good look for something that you have missed that is still connected, if not a neon in the back of a cupboard in the kitchen maybe a fused spur off to the central heating or an outside light, etc have known it to be something in the loft before.

 

[telectrix]

re - reading you post, think there is some confusion between continuity and IR testing.

 

[Deleted member 19807]

I am having a problem understanding the OP as well, the best thing to do is start at the beginning, cont test line, neutral, earth. do r1r2, r1rn, r2rn test at each point, then ir testing if others are all ok.

are you sure nothing is plugged in? under sink, behind dish washer, feed to shed, etc, etc.