insulation resistance testing bombshell

[sellers]

I do it that way and it makes complete sense to me.

Imagine you have a cooker cicuit and kitchen ring. One of the metal cooker feet is sat on a the kitchen ring T+E piercing the live. You isolate both circuits test IR no fault shows. The fault will only show when both earths are connected together.

 

[springcrocus]

IV, test cable fully isolated to check for damage.

Connect up then re-test, as described, this proves electrical separation also.

I always do it this way, too. Just in case some idiot carpenter or similar has pierced my cable between install and initialize.

 

[a12jpm]

:C Im confused as to how IR is checked here,

do we have to disconnect the earth, L&N and test, then reconnect and test again?

Ive only ever done it the same since I was taught,

check continuity(ring finals obviously) then connect, when everything is connected then global IR, if something shows up then disconnect til you find it.

Phew, thought it was just me missing the point. I close all the mcbs and IR test on the bars, only remove them if there's issues.

 

[steptoe]

so there is at least 2 of us that dont have a clue then a12jpm !? :|

 

[sellers]

No you only need to test it with the cpc in the earth bar. That will be the worst reading with the parallel paths in place.

 

[SPECIAL LOCATION]

I want to know, when did reg 612.3.1 change to say that cpc has to be connected in and bonding present? Who has old regs books lying around?Me? :red card I need to lie down a while...

Reg 612.3.1 is worded exactly the same in the red book... Page 158..

In the Brown flavour book it was called 713-03-01 was worded slightly differently.. page 172

and didn't specifically include that wording CPC connected... blah blah...

BUT..

IMHO it is the 612.3.2 & 713-04-02 that defines how to do the IR test...

that is ..

AT THE DISTRIBUTION BOARD WITH ALL FINAL CIRCUITS CONNECTED...

you only separate them off if you have lowish readings and you are trying to eliminate latent defects...

Now to my mind...

All final circuits connected means all the CPC are still in the earth bar!?

That is how the GN3 and OSG have always described it.

:C

 

[Apache]

From the replies on this thread my money is on the NICEIC bankrolling the Doc's book!

 

[markx]

Sorry guys I am still confused, only ever checked IR with cpc connected in earth bar. Is this right or wrong? From what steptoe says, it sound the same way I do test.

 

[SPECIAL LOCATION]

Sorry guys I am still confused, only ever checked IR with cpc connected in earth bar. Is this right or wrong? From what steptoe says, it sound the same way I do test.

Right!

see reg 612.3.1 & 612.3.2



what the Doctor is saying is a lot of sparks incorrectly remove all the conductors from the CU when testing..

Guinness

 

[SLIPSHOD & SLAPDASH]

I always do it this way, too. Just in case some idiot carpenter or similar has pierced my cable between install and initialize.

And me. Its common sense to me and i think what has not been addressed here is that your guy is wrong in saying most electricians do it wrong. Maybe a small % ?

---------- Post Auto-Merged at 00:33 ---------- Previous post was made at 00:30 ----------

YepNoz is right...

How long has the rule been in that the cpc has to be connected in? At the old electric board school they taught a guy to test and then connect it in

[...

I was taught that way in 77

 

[markx]

Thank god for that I can rest easy now.

Many thanks

 

[Sharpend]

Well I can vouch that reading the regs and GN3 works as I do exactly as it says in the book. Am I alone???

 

[ProDave]

I'm reading this thread with interest.

In the example of the live conductor nicked and shorted to the metal stud work.

Am I the only one that thinks it is TOTALLY implausible that you would get a reading of >199M ohms even with everything dry? I personally would have expected to get some reading, even if everything was bone dry.

so I'm struggling here to understand what you are getting at. I think in that unfortunate case, it's VERY likely the IR testing was "forgotten" and the spark responsible is perhaps just using the excuse of the "wrong" method of IR testing as an excuse to get him off the hook.

 

[NozSpark]

TBH I'm thinking that this statement is more due to the fact that on assesment they get you to do ring continuity and polarity, and then IR testing. With someone watching it is very easy to get a bit flustered and to forget to refit the CPCs and test from there,,,,,

Well that's my excuse anyway

 

[Manator]

I carry out initial insulation tests at first fix before boards are fitted, and then again when fitted to the boards. This way I prove electrical separation and pick up on any possible other trades damage. Testing this way saved my bacon many times and especially with those jumbo studs! I love them and hate them. I use wago connectors to connect circuits temporary to do the tests, then test when all accessories are fitted. It takes longer than the just bang em in method but I do not mind testing a circuit over and over again.

 

[Nicky Tesla]

what the Doctor is saying is a lot of sparks incorrectly remove all the conductors from the CU when testing..

Guinness

No....Thats not what is being said......Many people test the cables before fitting the cpc and do not recheck after it has been fitted in the CU.

Its not confusing at all........simple really

 

[Manator]

No....Thats not what is being said......Many people test the cables before fitting the cpc and do not recheck after it has been fitted in the CU. Its not confusing at all........simple really

It is obviously confusing some of us from what has been discussed, I would have to agree with Special Location, but am now equally confused by your statement. I guess it is not that simple after all, unless you are confused and we are all agreed?

 

[Sidewinder]

Nicky,

I think I see what you are saying, but is that what the doctor is saying?

Also, what if the cables are already in as it were in the state of an EICR?

In the case of IV then IMHO a before & after is the best way.

I suppose you could do a connected and disconnected on an EICR, but not strictly needed really.

I suspect one of the limits of this media?

 

[sellers]

In testing we are looking for the 'worst case scenario' reading. Therefore your readings with the cpc connected will always be the same or worse, therefore the reading you are looking to write down.

The same reason why we remove the CPC for R2 testing, to get rid of the paralel paths and find the worst (highest) reading so to speak.

 

[SLIPSHOD & SLAPDASH]

I carry out initial insulation tests at first fix before boards are fitted, and then again when fitted to the boards. This way I prove electrical separation and pick up on any possible other trades damage. Testing this way saved my bacon many times and especially with those jumbo studs! I love them and hate them. I use wago connectors to connect circuits temporary to do the tests, then test when all accessories are fitted. It takes longer than the just bang em in method but I do not mind testing a circuit over and over again.

I had done this on a job and had a Rcbo tripping out which got to the stage of not resetting. Cut a long story short it was a cable fault. I have the culprit but not much to show. Not had this before in all my years experience, will stick some pics up in the pictures section