PIR Insulation Resistance Test

[swift colin]

Just had a PIR done for a house we were hoping to buy.

The house - victorian/edwardian terrace - has 8 circuits and the wiring is approx 20yrs old according to the PIR.

The report gives the same reading for ALL circuits. Live-Live is 1.01 Mohms and Live-E is 0.17 Mohms. Continuity Polarity and Zs all seem OK. Each circuit having different (R1+R2) values and different Zs values.

I understand that the insulation resistance readings are not good and that further investigation will be required.

Despite reading (IEE books) about the test, the method of performing the test and the acceptable results I am none the wiser as to how 8 separate circuits tested independently can give the same reading.

Can anyone enlighten me as to whether this is possible? or give me some idea of what to ask the electrician who did the test so that I can have a meaningful discussion with him.


Thanks

 

[wallyanker]

When doing an IR test, U can test all circuits at once. If you then get results like yours, you would then go on to test each individual circuit untill you find the one that is not good.

 

[spark 68]

He may have carried out a global test, ie. on the whole installation at the consumer unit tails, and just filled in the same result for each circuit.

With readings this low, I would (although I do this anyway, regardless of a low global reading or not, unless it was above 10Megohms), is to carry out an IR test on each circuit individually, this would have shown up one or perhaps more faults on the individual circuits.

There may also be something still connected, eg. Neons, Alarms, Boiler controller,aerial amplifier etc..., this would give false low readings.

I would ask him how he got the same readings for each circuit, and if it is as above, ask him to re-test properly.

 

[swift colin]

Wallyanker and Spark 68. Thank you. Unbelievably quick replies.

 

[micknew]

With those readings there is almost certainly equipment connected so they don't really mean much.
There could even be 1 circuit feeding outside equipment with dampness giving the low readings.

 

[NMc]

Looking at a small piece of a PIR is not going to tell you what questions to ask your electrician. But the readings you have stated would suggest that a global test has been done. GN3 says that any result under 2Meg requires further investigation which is what should have happened. You say Continuity Polarity and Zs all seem OK but what are you compairing against? Each circuit having different (R1+R2) values and different Zs values - you would expect this but on PIRs I would be doing R2 readings

What was your brief for the PIR? PM me if you wish to discuss off the open forum

 

[Ponty Massive]

I tend to do a global IR test to begin and also R2 tests instead of R1+R2.

 

[needasparks]

I was going to say the PC was plugged in but the OP posted on here. so the equipments not fried.

 

[adamh]

how are you doing an r2 test? is it with a wander lead?

 

[Ponty Massive]

how are you doing an r2 test? is it with a wander lead?

Yes indeed

 

[RISElectrical]

I tend to do R2 tests however usually R1+R2 if it's a ring

 

[Octopus]

Back to the OP - what was the outcome of the EICR? Satisfactory? Unsatisfactory? If the later what are the comments and codes.

IMHO the IR readings must be suspect and as others have said they must have been done on a "global" basis which isn't giving you a real picture of the install.

I'm guessing you've paid his bill!

 

[GLENNSPARK]

when on a PIR i will hit it first (IR) at the tails...see what i get....if i dont like it (under 10 meg)....then i will do em all individualy.....theres either a connected load here .....or water in a fitting someware....outside maybe..but i think thats already been mentioned here already.....whether the R1 R2 method....or just a plain R2 method is used is neither here nor there.....it would also depend if you had your wander lead with you..(maybe it got left out of the van)..who knows...but........
what should have happened here of course is this `electrician` should have immedietly given this a (3)...but ready to go to a (2)...upon further investigation when the offending circuit/s had been found........which doesn`t appear to have happened here....hmm.....

 

[Octopus]

when on a PIR i will hit it first (IR) at the tails...see what i get....if i dont like it (under 10 meg)....then i will do em all individualy.....theres either a connected load here .....or water in a fitting someware....outside maybe..but i think thats already been mentioned here already.....whether the R1 R2 method....or just a plain R2 method is used is neither here nor there.....it would also depend if you had your wander lead with you..(maybe it got left out of the van)..who knows...but........
what should have happened here of course is this `electrician` should have immedietly given this a (3)...but ready to go to a (2)...upon further investigation when the offending circuit/s had been found........which doesn`t appear to have happened here....hmm.....

I wonder how much the OP paid for the EICR? Me thinks it was underpriced and he/she didn't allow sufficient time to do a proper job

 

[GLENNSPARK]

I wonder how much the OP paid for the EICR? Me thinks it was underpriced and he/she didn't allow sufficient time to do a proper job

well this is it Murdoch.....all easy n well to point out what a naughty `sparky` he was....but lets face it....unrealistic budget+unrealistic timeframe......we get this all the time....and not just on PIRs either.....like the other day we were on a job and after about 1 hour or so of being in there..she came out of the living room askin us `how long will it be`?....this on a job that was expected to last all day.....the client knew this n all......