EICR Help required from some of you testing experts.

Please help, I'm still new to testing for myself and sometimes I wonder if my new Megger is being naughty on purpose as my Fluke wasn't as prone to throwing up weird results as my Megger.

So a mate has been doing very small works on a property and as he's there he finds pd's tripping on other circuits and strange faults so got a bit of a wobble and asked me to go do an eicr on the premises so agreed 50% sample with the owner.

I have had a good few hours on site today and not gotten very far due to the state the board was in, lack of correct labelling and so on...

Advice I'm looking for is I found a 2 gang dimmer hanging off wall which subsequently found is fed from a 32A ring and through a fused spur at 13A before ending feeding the said switch ! One dimmer is switching a load of LED downlights inside, other is a dummy dimmer / ordinary push on /off switch covering ground lights along outside wall which seem to be full of water droplets / condensation ! the suspected switch line to the out lights was discon in back of box, reconnected and switched all on, 10 seconds then bang and the back of the dummy dimmer was black as .... no 1362 fuse blown in spur and no rcbo tripped but switch was shafted cannot believe rcbo didn't trip ?? thinking must be shorted light fittings out there.

Next issue is on downstairs sockets, tests r1,rn, fine but r2 relationship 2.5/1.5 ratio is way off ! r1 0.44, rn 0.44, r2 16.8 kOhms !! wtf ?
Thinking nasty connection on cpc somewhere anyone seen similar before ripping apart the circuit.

R1+R2 was o.k. though.
IR was a real pain as the meter did not want to know: @500V L-E max was 1.01 Meg
N-E was 0.36 Meg !
But sure every single thing was unplugged.
Also when tested at 250V the readings all came out approx 25 Meg ! ??

What was even more weird was that entire board was off and locked off and every breaker or rcbo was open too. but while doing the downstairs sockets R1+R2 I tested the same at kitchen sockets which are a separate ring and they gave a result of 20+ K ohms ! surely the separate circuit should not have even registered ?

Following this the kitchen ring was tested and was o.k. until IR test again,
L-E max would go to was 30V
and L+N-E would not ramp up at all ! 0V
L-N also 0V would not ramp up at all.

Anyone ever seen any weird issues like these when trying to IR test or similar ?
I know the Megger will inhibit IR if it senses voltage above touch or a high resistance I think it was ? but is this likely or is my new MFT no good ?

Any ideas would help loads, Thanks.

think iwillpasson this one till the beer's worn off. toomuchinfofor a befuddled brain ( and that's when i'm sober)

telectrix said:

think iwillpasson this one till the beer's worn off. toomuchinfofor a befuddled brain ( and that's when i'm sober)

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Tel, good on you, my heads battered with it today.

Restrict the use of your all singing all dancing multi functional contraption for installations that are going to be straight forward
In the meantime get yourself a single instrument insulation resistance/continuity analogue meter,the system will then reveal its status more clearly than using a instrument that has too much influence on what and when it needs to function

never blame your instruments. see the kegworth/M1 airplane crash.

Des 56 said:

Restrict the use of your all singing all dancing multi functional contraption for installations that are going to be straight forward
In the meantime get yourself a single instrument insulation resistance/continuity analogue meter,the system will then reveal its status more clearly than using a instrument that has too much influence on what and when it needs to function

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like this:

The poor dears these days wouldn't entertain the work involved turning the handle,it would never get up to speed and generate enough umph

Seems you have discovered why the external lighting was dissed. You are making the error of trying to find solutions to issues you are discovering instead of carrying out an EICR and itemising these issues in the Report. The problems with your meter is the reason I stick to individual meters and crack on with the job as opposed to fiddling with a temperamental meter.

So the question is - do you believe you results reflect the installation, or not? Is the kitchen ring IR result off because there is still something attached to it? I'd have another look perhaps then get on and record the result. Sounds like a few faults to be found later .

Des 56 said:

Restrict the use of your all singing all dancing multi functional contraption for installations that are going to be straight forward
In the meantime get yourself a single instrument insulation resistance/continuity analogue meter,the system will then reveal its status more clearly than using a instrument that has too much influence on what and when it needs to function

Click to expand...

Been told this before and kindly even been lent a solo IR tester to check an install but still had the exact same issues ! so thinking it's probably not the test kit.

Record your findings in the Report, investigate later.

Des 56 said:

The poor dears these days wouldn't entertain the work involved turning the handle,it would never get up to speed and generate enough umph

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I'm old enough we had them at college years ago !

Best way to locate the high R2 on the ring is to connect only one cpc leg to the earth bar and test for Zs all round. With a continuity result in kOhms, you should see a massive rise in Zs value between two of the sockets, one of which will likely contain the loose connection

Thanks all so far, as I say I tried a solo IR tester before and it still wouldn't ramp up test jolts on a similar nightmare job. Did find a few stashed sockets with built in fridges in back of kitchen units etc.. but thought I had unplugged it all, no client home to check if more still hidden / connected ! Also owner did say 4 different electricians had worked on premises before over the years as so many different extensions / builders had done works and no certs or anything offered for works on electrics before !!

Highresdis said:

Best way to locate the high R2 on the ring is to connect only one cpc leg to the earth bar and test for Zs all round. With a continuity result in kOhms, you should see a massive rise in Zs value between two of the sockets, one of which will likely contain the loose connection

Click to expand...

Thanks, never heard that one before.