IR testing Global or Partial (off topic discussion from another thread)

[ADS]

{The first 18 posts in this thread have been removed from another thread due to the apparent hi-jacking of someone else's question, (A new members first post!) and taking it even more off topic than it had already drifted.

Original posts can be seen here.

http://www.talk.electricianforum.co.uk/inspection-testing/17503-insulation-resistance-testing-socket-outlet.html#post236017

We aim to keep the forum open for all manner of constructive debate, (even the wording of BS7671 and its related publications), but if you wish to argue these topics, please have respect for the original thread starter's question. They do not want to keep checking back for more helpful information of their thread topic only to find some member calling other members smart a***s or T*****s This is not acceptable or within the forums T&C's which can be read here.

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Thank you

Doc H.

}

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Moved posts commence here:

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anything else i should keep in mind about this,

I wouldn't call testing IR at a socket outlet a 'quick and easy test'.

Even testing L&N connected together to Earth, I would still want all loads removed - in particular, anything plugged in, any transformers, dimmers etc.

The reason I say this is that, although we know that the chances of equipment damage is minimal when testing 'live' conductors together to earth - when, by pure coincidence, the customers computer no longer works after your visit, they're going to say "It was fine before you plugged your tester in to my socket"!!

So, be wary, not such a simple test.

....if the IR test result for the whole install is within the regs, then the IR of any single cct must compy.

IR testing is meant to be done on the whole installation (or section of installation e.g. at each DB) - it's not meant to be done circuit by circuit...........the figure that we need to comply with is meant for the 'whole' installation.

GN3 states: PG 38

Simple installations that contain no distribution circuits should be tested as a whole.

 

[Andy™]

i was just getting use to the peace around here

 

[Andy™]

IR testing is meant to be done on the whole installation

ROTFWL

you really must be a plumber!

 

[Sidewinder]

I wouldn't call testing IR at a socket outlet a 'quick and easy test'.Even testing L&N connected together to Earth, I would still want all loads removed - in particular, anything plugged in, any transformers, dimmers etc.

The reason I say this is that, although we know that the chances of equipment damage is minimal when testing 'live' conductors together to earth - when, by pure coincidence, the customers computer no longer works after your visit, they're going to say "It was fine before you plugged your tester in to my socket"!!

So, be wary, not such a simple test.

IR testing is meant to be done on the whole installation (or section of installation e.g. at each DB) - it's not meant to be done circuit by circuit...........the figure that we need to comply with is meant for the 'whole' installation.

GN3 states: PG 38

Yes ADS, in sub section 2.7.7.

Section 2.7 relates ONLY to INITIAL TESTING. It even says to in the heading!

NOT periodic testing, NOT testing with regard to modifications.

It also says that other appropriate test methods are NOT precluded.

Please check your facts before posting, as it may well confuse learners and result in them failing exams, which is not good for them.

 

[Riggy]

Please check your facts before posting, as it may well confuse learners and result in them failing exams, which is not good for them.

Here we go again!

 

[SPECIAL LOCATION]

IR testing is meant to be done on the whole installation (or section of installation e.g. at each DB) - it's not meant to be done circuit by circuit...........the figure that we need to comply with is meant for the 'whole' installation.

GN3 states: PG 38

Half the info I me-thinks...

Carry on reading down the rest of page 38....

read the other half..

it sounds to me like you haven't quite reached the last but one paragraph?

Something along the lines of:-

where an insulation resistance of less than 2 Mohms is recorded the possibility of latent defect exists. In these circumstances, each individual circuit should be tested separately.

Just in case you missed it...

Thats Page 38 of Guidance note 3, where it does say in these circumstances that

"each individual circuit should be tested separately"

if anyone is interested!

:C

 

[Sidewinder]

Here we go again!

Riggy,

Your problem is?

The guy has posted information which does dot meet the details written in GN3.

Why should this not be picked up?

 

[SPECIAL LOCATION]

Here we go again!

eh?

Do you think it best to leave miss information posted in threads and no one questions or counters someone elses statements...

Thought thats one of the things the forum was for?

Must have been mistaken

:C

 

[Nicky Tesla]

Here we go again!

i think i know what he means:innocent

 

[ADS]

Here we go again!

Yes Riggy, you're right, here we go again!!

[quote name='Andy

 

[SPECIAL LOCATION]

GN3 PG 75 The section on PERIODIC TESTING..........Top of the page!!

Where practicable, the tests may be applied to the whole of the installation with all fuse links in place and all switches closed.Alternatively, the installation may be tested in parts, one distribution board at a time.

NOTICE :- One Distribution Board at a time....NOT one circuit at a time!!

I think the phrase "MAY BE"... carries some relevance...

and I think you missed a paragraph...

skip back to bottom of page 74 under the heading

b Insulation resistance

Insulation resistance should be made on electrically isolated circuits with any electronic equipment ... etc.. disconnected

SHOULD be made on isolated circuits

-vs-

MAY be made on whole installations or diss boards..

We are all aware that you can IR a whole board..

but your stance that it SHOULD only be whole boards is factually incorrect...

(just for the record.. yes I have passed 2391.)

Notwithstanding the fact that the OP was asking about testing a circuit prior to doing an alteration..

NOT asking about doing a PIR..

Nor the fact that it was you who posted..

IR testing is meant to be done on the whole installation (or section of installation e.g. at each DB) - it's not meant to be done circuit by circuit...........the figure that we need to comply with is meant for the 'whole' installation.

 

[ADS]

As a side-question to all you smart a***s who are so quick to shoot me down.

If I am wrong and you are right, what happens when you disconnect your 'line', 'neutral' and 'CPC' of your circuit from the board to IR Test and all the results are 100 % - but what you won't know is if there is low insulation resistance between your circuit 'line' conductor and the neutral or CPC of another circuit - two damaged cables running together or a conduit/singles installation.

Not so clever now, are you??

---------- Post Auto-Merged at 00:44 ---------- Previous post was made at 00:32 ----------

I think the phrase "MAY BE"... carries some relevance...

I think it's relevant, too.

It's giving you the option of the two - It may be performed on the whole installation.....Alternatively, it may be performed at each DB

...and I think you missed a paragraph...

skip back to bottom of page 74 under the heading

b Insulation resistance

Insulation resistance should be made on electrically isolated circuits with any electronic equipment ... etc.. disconnected

Again, the obvious.

All the circuits are electrically isolated when I IR test the whole installation at the CU - it would be foolish not to.

---------- Post Auto-Merged at 01:05 ---------- Previous post was made at 00:44 ----------

To cut to the chase,

Yes, Specs, I did say 'meant to be done'......not 'has to be done'

You see, 612.3.2 applies, and there's really no arguing with what that says.

It's like the old question - you must have heard it.

11 final circuits, each with a measured IR of 10 Mohms - Does the installation pass with a 'satisfactory IR reading??

 

[SPECIAL LOCATION]

As a side-question to all you smart a***s who are so quick to shoot me down.If I am wrong and you are right, what happens when you disconnect your 'line', 'neutral' and 'CPC' of your circuit from the board to IR Test and all the results are 100 % - but what you won't know is if there is low insulation resistance between your circuit 'line' conductor and the neutral or CPC of another circuit - two damaged cables running together or a conduit/singles installation.

Not so clever now, are you??

Go back and read the OP's question....

1/ Where do you get the impression we are talking about a conduit job?

2/ Where do you get the impression we are talking about PIR's?

3/ If you are going to work on one circuit... how much time are you going to spend investigating faults on other non related circuits to the minor works that you have been asked to do? and who will pay for it????

4/ What if its NOT practical to turn off a whole installation?

5/ Why do some people try and draw other peoples threads off topic for their own arguments?

Just for the record:

No-where does GN3 state that you MUST ONLY IR test whole installations at their DB..

What it does say is the test considered appropriate by the person carrying out the inspection will be used and they give various guidance options and expected results for those options.

Oh..

by the way when having an annual assessment with your approved contractor schemes inspector..

how do they ask you to do an IR test?

:C

 

[ADS]

What, have you run out of argument now, so picking bones in my postings??

Listen,

The OP said:

........ but if the IR test result for the whole install is within the regs, then the IR of any single cct must compy.

To which I replied:

IR testing is meant to be done on the whole installation (or section of installation e.g. at each DB) - it's not meant to be done circuit by circuit...........the figure that we need to comply with is meant for the 'whole' installation.

Which happens to be backed up by Regulation 612.3.2.

I then got bombarded with posts about how wrong I was and how I shouldn't post false information, so I went on further to explain myself.

So I WAS on topic to begin with - until the bitching started!!

Go back and read the OP's question....1/ Where do you get the impression we are talking about a conduit job?

I did say:

As a side-question to all you smart a***s who are so quick to shoot me down!

2/ Where do you get the impression we are talking about PIR's?

Sidewinder brought this up when I mentioned GN3.

3/ If you are going to work on one circuit... how much time are you going to spend investigating faults on other non related circuits to the minor works that you have been asked to do? and who will pay for it????

Talk about relevance???

4/ What if its NOT practical to turn off a whole installation?

A whole other argument and debate - live board etc.......talk about going off topic!!

5/ Why do some people try and draw other peoples threads off topic for their own arguments?

As explained, I didn't - I was responding to an observation by the OP

Just for the record:

No-where does GN3 state that you MUST ONLY IR test whole installations at their DB..

What it does say is the test considered appropriate by the person carrying out the inspection will be used and they give various guidance options and expected results for those options.

I never said it 'MUST ONLY'' be........but see 612.3.2

Oh..

by the way when having an annual assessment with your approved contractor schemes inspector..

how do they ask you to do an IR test?

Hasn't asked me to - but if he does, I'll tell him what I've told you.

:C

Is that it - you out of argument on the IR topic??

 

[SPECIAL LOCATION]

Hmm?

As the thread had been moving quite reasonably with healthy debate until certain members started posting

AND..

The OP was happy with the answers given...

It could be said that it looks like its one person who is trying to argue?

(That same person is the one using impolite language as well!)

GO back again a check post #24..... The OP's comment is interesting no?

My question also relates only to Minor Works and NOT EIC or PIR

Now have a look at a MWC (pg 335 red book)

Oh yes.. it does ask for IR along with Polarity, Earth loop, Earth continuity ..

for the circuit you have altered..

So what are you on about one minute talking PIRs... Which the OP says he's not interested in!

then on about testing new installations (612.3.2),

section 61 is INITIAL VERIFICATION... which the OP says he's not interested in!

Which IMHO is only likely to confuse and mislead any student electricians reading the posts...

as for....

IR testing is meant to be done on the whole installation (or section of installation e.g. at each DB) - it's not meant to be done circuit by circuit...........the figure that we need to comply with is meant for the 'whole' installation.

.....it could be said that IF we are only interested in a global IR figure...

why oh why oh why do they give space for IR readings for each & every circuit on a schedule of tests results?

Pg 341 of the red book in case you have forgotten...

Surely it would have been best just to put a global 'IR' box on the particulars of installation page?

Or perhaps yours do? :C

You have never been asked to perform and IR test at an assessment?

Do we deduce from that statement that you are not a member of any approved contractor scheme?

There is little point discussing anything with a person who ignores basic facts common sense and underlying electrical science.

As such I will not contribute any further to this thread because it is my understanding that the OP has been answered.

:C

 

[Sidewinder]

ADS,

NO apology will be forthcoming.

YOU referred to page 38 in GN3, NOT anywhere else.

My answer was based on THAT statement, so I was NOT incorrect, you were.

You have now gone and found other locations for information which were NOT the subject of your first INCORRECT post.

Which may well be fully relevant I am not going to dispute that.

I still maintain that your first post was incorrect, as the section on pg38 is with regard to initial testing.

I had no need to check anything else as I was answering a specific point which you made incorrectly.

IF you had put in the other references, then there may well have been relevance, but you did not, you stuck to a single incorrect reference.

 

[ADS]

Hmm? As the thread had been moving quite reasonably with healthy debate until certain members started posting

AND..

The OP was happy with the answers given...

It could be said that it looks like its one person who is trying to argue?

(That same person is the one using impolite language as well!)

The impolite language arises from the condescending comments that I receive from certain members whenever I have an opinion......right or wrong

GO back again a check post #24..... The OP's comment is interesting no?

My question also relates only to Minor Works and NOT EIC or PIR

The OP asked about doing a 'Whole Installation' IR test from a socket outlet - he was working on a lighting circuit - so my comments were perfectly on topic.

He said:

If i were to leave the Main Switch off and all the MCB's closed (on) and perform my IR test at a socket outlet between L-E and N-E only, surley this will test the whole install and be adequate for a Minor Works if the readings are compliant,

The answer, of course, being yes, subject to a couple of other checks.

Now have a look at a MWC (pg 335 red book)

Oh yes.. it does ask for IR along with Polarity, Earth loop, Earth continuity ..

for the circuit you have altered..

So what are you on about one minute talking PIRs... Which the OP says he's not interested in!

then on about testing new installations (612.3.2),

section 61 is INITIAL VERIFICATION... which the OP says he's not interested in!

OK -Read 621.2 FIRST, which will refer you back to Chapter 61 and, therefore, 612.3.2

This regulation gives the required result for comparison with the table- you can't argue with that.

Which IMHO is only likely to confuse and mislead any student electricians reading the posts...

If the students are taught correctly, they will be told that the required IR figure, for comparison with the table, is that of the whole installation, as per 612.3.2..........No Confusion.

If you wish to do individual-circuit IR testing, that is, of course, your perogative - but it's not a requirement, unless further investigation is required.

as for....

.....it could be said that IF we are only interested in a global IR figure...

why oh why oh why do they give space for IR readings for each & every circuit on a schedule of tests results?

Pg 341 of the red book in case you have forgotten...

Surely it would have been best just to put a global 'IR' box on the particulars of installation page?

This has to be your weakest argument yet.

If you are required to do individual-circuit IR tests, then you can insert individual results in the boxes.

Perhaps a similar reason as to why the certs have a RCD trip time box for each circuit- so that if your testing RCBOs, you can put in individual results........BUT, if your testing a dual RCD board, then half the boxes are going to have the same figure in them.

Or perhaps you think the one RCD should be tested on each circuit it protects???

You have never been asked to perform and IR test at an assessment?

Do we deduce from that statement that you are not a member of any approved contractor scheme?

You can deduce what you like - my assessor is more than happy with my ability and does not need to see me perform an IR test.

There is little point discussing anything with a person who ignores basic facts common sense and underlying electrical science.

Really??

As such I will not contribute any further to this thread because it is my understanding that the OP has been answered.

:C

Hmmm?

There's a surprise - it doesn't stop you normally.

Ifyou thought you were right about this, we'd be getting a 1000 word lecture/post around about now.

 

[Doc Hudson]

IR testing is meant to be done on the whole installation (or section of installation e.g. at each DB) - it's not meant to be done circuit by circuit...........the figure that we need to comply with is meant for the 'whole' installation.

GN3 states: PG 38

I would just make clear, IR testing is meant to be done on the parts of the installation you are contracted to work on. If it is minor works then it will be the circuit(s) you are working on, not the whole installation. If it is a full rewire it will be the whole installation. If it is a PIR it will be on the extent of the installation that has been agreed with the client. Even if it is a whole PIR then it may well not be possible to de-energies a whole installation or sub main's DB at the same time. work may have to be done in stages to ensure critical areas still have power whilst testing other areas. This is where the interpretation and skill of the competent person undertaking the work will be applied. Anyone expecting to see a black and white set of rules and procedures in the wiring regulations, telling them how to do every job will be disappointed. Electrical work is a daily risk assessment and evaluation process to achieve a specific task.

Doc H.

 

[Nicky Tesla]

" A daily risk assessment" good comment

also slip in the word "practicable" somewhere that may help

And for PIRs, it is best to do the least amount of dismantling as practicable, as this may introduce faults and risks.

 

[m4tty]

I forgot something off my risk assessment today. It was are the tiles the other side of the wall going to fall off whilst chasing a box on other side of wall. Oops lol