Insulation resistance help on a ring main.

[schoe]

Hi all having a few issues with an insulation resistance test on a ring main. Firstly carried out my continuity test,

End to end,

L-l 0.93 n-n 0.90 e-e 1.46
R1+n 0.47 r1+r2 0.61

So then moved onto the insulation test.

Checked all the sockets for tightness, made sure nothing was plugged and disconnected the wires from the consumer unit to test separately.

L- n <500
n-e <500
then l-e 246.

Now I no this is an acceptable reading on the line to earth but the cable is newly installed so don't understand why I'm getting the lower reading.

I've even check each leg of the ring by disconnecting the socket and doing an insulation resistance test in-between each leg. After completing this though every leg passed the 500 mohms. But when I re tested the circuit as a whole I would get the same lower reading again. I really don't understand why, if anyone could offer any advice i would really appreciate it.

Like I said before all the wires were disconnected from the consumer unit and nothing was plugged into any of the sockets.

Oh and I have even put all the ring in choc blocks to make sure the sockets weren't faulty but I still got the same results.

King regards chris

 

[telectrix]

any new plasterwork?

 

[telectrix]

r1+r2 0.61 : don't you mean R1+R2?

 

[schoe]

Sorry R1+R2. yes there is newish plasterwork, it was done last week on the face of it though it looks dry enough to paint. The N-E reading is good but it's laboured on the meter, it doesn't automatically go to 500 m ohms it's works it's way up but it does get there. So do you think it could be the plaster, everything was capped?

 

[SPARTYKUS]

As Tel says probably plaster, expect it'll be alright in a month. Wouldn't worry the figure of > 246 Million Ohms is not going to worry anyone.

 

[schoe]

My only concern is I'm thinking of using this re-wire to show the niceic so I can hopefully become a domestic installer so I want everything to be perfect. I'm pretty nervous about them coming even though I've done my three years at college and past my 17th edition. If I show an inspector a schedule of test results with everything else stating 500 m ohms and this different is he likely to question it?

Also the rest of the house has been plastered and I noticed the same laboured results on the upstairs ring. It didn't do it on the lighting though. I was considering taking floor boards up today, even though the plaster looks dry on the face of it, and there wasn't any condensation in the back boxes do you still think it could be the plaster? I'm sure you are all right as I'm pretty new to this and have never come across plastering issues before!

Thanks chris

 

[schoe]

I'm still waiting for the plaster to dry :8:

 

[telectrix]

makes me glad that my mft only reads to >199meg.

 

[SPARTYKUS]

I'm still waiting for the plaster to dry :8:

schoe - he'll be impressed with your honesty. The worst thing ever is looking at a sheet of results and knowing it's made up.

don't worry you'll be fine.

 

[telectrix]

you coiuld even put on your test results >10M. for all circuits. all the regs. require is that the readings are >2M.

 

[mattmoo1974]

I just write my phone number backwards across those papery bits at the end, And if the portal Loo is out of paper you wont get any test results!

 

[tc50]

why wouldnt it show up on ir test of each leg though ..... just interested

 

[schoe]

Tc50 that's what I was thinking! is there anything in the regs brb about it?

 

[schoe]

Telectrix your usually my oracle what do you think about tc50's post?

 

[bsrfc10]

But it is R1 not r1!