Testing Thoughts

[Pretty Mouth]

I started to run the Insulation resistance tests @ 250v which most circuits passed with no issues apart from the Ring Main Sockets which. I got a >999 for Neutral to Live but I got a low reading of 112 ohms for Live to Earth. For 500v I got a measurement of 600 ohms Neutral - Live and 120 ohms for Live - Earth. A couple of the other circuits also struggled at 500 volts.

@mackatoon there's something not right here. I don't see how you can be getting those results from an IR test.

IR tests return results in meg ohms. 1 meg ohm = 1,000,000 ohms. 120 ohms would show a reading on your meter of 0.00012 meg ohms. Is that really the reading you got at 500V? My meter only has a resolution of 0.01 meg ohms for IR tests.

I suspect, as @westward10 has suggested, you are confusing meg ohms for ohms.

 

[DPG]

I tried 3 lead and was still getting the low result

Can you clarify this, bearing in mind you are doing IR tests.

 

[7029 dave]

If possible could you get a picture of the test results.

 

[timhoward]

In addition to the logic above which I agree with, it was mentioned that R1+R2 was carried out and was ok, and in my head that simply can't be the case if there's really 120 ohms in parallel between R1 and R2, even at the much lower voltage that test uses. (Might be red herring but was R1+R2 done at board or a socket, and if a socket are you sure everything properly re-terminated)

More generally - it's really easy to get increasingly stressed and for rational judgement to go out of the window when IR tests do strange things. Been there plenty of times! I think it was @westward10 who told me once the results were only getting worse each time due to the increased sweat on my fingers affecting the resistance!
New day, cup of tea (solves most electrical problems) and calmly start again I reckon. Please do report back, you have a bunch of us interested now!

 

[Dartlec]

Are there any fuse spurs with old neons in? They can often show up poor IR results - as can extension leads with neons (not so much the more modern LED ones).

But the key is to approach it calmly and if getting odd readings try to isolate it.

If there are only 1-2 sockets per room and tenant is using lots of extension leads then a rewire is probably advisable at some point (assuming the wiring is not recent and just stingy with sockets), but that's very different from being necessary on an EICR.