IR Test

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avinalarf

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Evening folks

Been going over (& over) testing and did an IR test on my downstairs ring and got the following reading which concerned me somewhat; line to neutral = 0.67! Neutral to CPC was 175 megohms and line to CPC was 143 megohms. I'm assuming that these readings indicate a breakdown of insulation, but can anyone suggest why the line - neutral is so much lower???

Also, is there some way which I can detect exactly which part of the ring may be most affected?

Many thanks

 

steptoe

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something plugged in,

or a neon indicator somewhere switched on.

that would be most logical explanation, before I would even start looking for a fault.

do you have a TV amp/one of them silly air fresh things etc or something maybe you forgot about?

 

avinalarf

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Thanks Steps, but there was definitely nothing plugged in when I did the test!

 

kme

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Evening folksBeen going over (& over) testing and did an IR test on my downstairs ring and got the following reading which concerned me somewhat; line to neutral = 0.67!

As in 0.67 Megohm? seems low for a neon; but, as steptoe says, TV amplifier, plug in air freshner etc.

To try and find it, break the ring approx half way round; AND at the CU, and see which half has the reading on. If necessary, keep splitting until you find the section which contains the load. You`ve got SOMETHING loading the circuit, something small.

Neutral to CPC was 175 megohms and line to CPC was 143 megohms. I'm assuming that these readings indicate a breakdown of insulation, but can anyone suggest why the line - neutral is so much lower???

Also, is there some way which I can detect exactly which part of the ring may be most affected?

Many thanks
No problem

 

avinalarf

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Shall start re-testing on Monday.

Many thanks & I bid you "goodnight".

 

SPECIAL LOCATION

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your line - neutral and CPC are fine BTW.
Absolutely!! ;)

N - CPC 175Meg

L - CPC 143Meg

All ok and good..

Remember because the L & N are opposite sides of a bare CPC in the cable..

IF the cable were breaking down one or both of the readings to CPC would probably be going LOW! ;)

Don't forget any Fused spurs?

Boiler?

FCU & PIR to an outside light off the ring?

FCU & extractor hood / fan

Under counter kitchen lights can often be off the ring?

Got any 24hr timer clocks on the circuit?

Ignition for gas hob?

Fridge Freezer? e.g An integrated appliance somewhere in kitchen?

I have read 0.25Meg directly across neon @ 500v test?

If you have a neon FCU in your kit at the moment test across it yourself to see the sort of thing you can get! ;)

:D

 

avinalarf

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Thanks Special

Found the offending FCU in utility room! All readings ok now.

 

SPECIAL LOCATION

Trailer Boy - Electrician.
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Thanks SpecialFound the offending FCU in utility room! All readings ok now.
Applaud SmileyApplaud SmileyApplaud Smiley:^O

well done m8!

Tis my theroy that FCU's go and hide when they know someone is comming to to a PIR or simmilar...

when its gets dark they go a roamin! :eek: ; \ :)

 

M107

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When I was brushing up on the IR testing prior to the 2391 a few years back, I forgot about the kids night light tucked away at the end of the bed.........wasnt till I'd started dividing the ring I came across it Blushing........how f***ing miffed was I.......mind you the kids were more p***ed as the night light didnt like 500v up it :_|

 

Mark2spark

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When I was brushing up on the IR testing |
I did laugh at that! I mean don't you do it (IR) then?

I know most of us skip some of the tests but IR? Blushing

Not throwing stones here y'know :D

 

cheggers

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I always test a 250v first then 500v shows up anything plugged in before you blow it to bits.

 
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