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Topic Title: minor electrical works
Topic Summary: nice easy certification entry question
Created On: 27 July 2013 08:58 AM
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 27 July 2013 08:58 AM
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psychicwarrior

Posts: 220
Joined: 18 October 2010

last night i got thinking (it wears me out)
and i could be a little embarrassed to be asking this but....

if one is certifying only the new work done and presuming too that the installation was suitable for the addition/alteration in the first place:

taking insulation resistance for example, the new work (say, for example, extending a lighting circuit or a radial socket) may return a significantly better/max. value [for the meter] than the existing it is tagged on to.

incidentally, it may only be possible to do L-N/CPC on an existing!?
and i presume we all check the circuit before starting to ensure no probs. in any case.

(reminder to self) IR guidance these days is to have everything finished off etc and to ensure the circuit is connected to the earth bar before this test - so that suggests the whole circuit can only be tested and recorded ;-)

briefly; i did 'ask' a while ago about recording Zs in this type of situation and most replies suggested Zs at the 'last point' of the new work - with a note possible of a Zs downstream as applicable, to show the work didnt affect anything.


so...what is/should be written on the cert. (and what if only L-N/CPC done due to many things to disconnect) - the IR values for the work done, as that's what the extent is as such (but accepting one can not really do the test as per guidance), or the whole circuit value from the board, which may reflect downwardly or not accurately of the new work due to existing circuit conditions covered by the cert?

given both values will both be decent - does it even matter..for accuracy or otherwise!

keep safe. regards
Habs
 27 July 2013 09:53 AM
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davezawadi

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The important bit is the overall IR of the circuit, so that is what you record. No one else is likely to measure just the extension are they?

Regards

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David
CEng etc, don't ask, its a result not a question!
 27 July 2013 01:48 PM
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psychicwarrior

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yes, that's true obviously...... i was musing on the certification (extent) of the work done against some possibly low readings on stuff not part of the extent as such.

incidentally, on a large circuit (as in many accessories etc) - do folks price up for removing all bulbs and other stuff before doing their extent of alteration work and associated tests to complete fully the L-N, L-CPC & N-CPC. ..... i guess so.


any way........ i suppose this is a bit of a dull subject to have posted on :-)
as i say, was only musing
 27 July 2013 04:54 PM
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weirdbeard

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Originally posted by: psychicwarrior


any way........ i suppose this is a bit of a dull subject to have posted on :-)



Wiring and the regs forum....on a saturday.....dull....? Surely not!!!!

To liven things up...I disagree with Dave

I say that for a minor works cert you only need to record the insulation resistance readings for the new bit in part 3, and any additional readings taken of the existing installation are best commented on in part 2.
 27 July 2013 05:49 PM
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redtoblackblewtopieces

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Well I have to disagree with weirdbeard , if doing an addition or alteration I would expect my work ( or anybody else's) to be +500 meg
For IR so what would be the point of recording this if everybody was recording the same. On limitations I tend to write from circuit
Protective device to end line of new wiring only as regards testing although I do record Ze and PFC as well.
Kevin

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 27 July 2013 06:35 PM
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weirdbeard

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Originally posted by: redtoblackblewtopieces

Well I have to disagree with weirdbeard , if doing an addition or alteration I would expect my work ( or anybody else's) to be +500 meg

For IR so what would be the point of recording this if everybody was recording the same. On limitations I tend to write from circuit

Protective device to end line of new wiring only as regards testing although I do record Ze and PFC as well.



My tester only goes to 200 MΩ

Limitations are only noted for EICRs, there is no section on the MWEIC for limitations.
 27 July 2013 07:40 PM
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redtoblackblewtopieces

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We must use different forms , I use easycert and the agreed limitations section are at the bottem of section 3
Kevin

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 27 July 2013 09:56 PM
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psychicwarrior

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hmmmm - just poking in and amongst whats been said

i just thought it was all a bit odd at the time it popped into my head, as i can see that the 'whole' circuit IR should be recorded, yet that's not what your cert is covering work wise as you are not responsible for existing...except only in that you did nothing to harm the existing and it was suitable for the alteration/addition work to take place.

i.e. a circuit may give 50 MOhms - its still ok - but it aint your work is it and unless you record what your stuff is somewhere - there is no record.

my view is, it doesn't have to matter so long as it complies - i was just musing over the 'liability is only for the extent of the works undertaken and recorded on the cert' - yet some tests recorded are for the whole circuit inc. what you didnt have owt to do with and that may not be reflective of the stuff you actually did :-)

that just leaves the - the circuit has some real fancy lighting - enclosed bulbs, crystal lights, controls, lights high up, fluorescents etc...... lots of bulbs..........big and tiny across a fair few rooms...... its a pig to taken em all out of circuit to do the IR.... so what do you do..... L-N to CPC and just record that! for your MEIWC.


hehehe.... by eck, this lagavulin is nice!
 27 July 2013 10:00 PM
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weirdbeard

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Originally posted by: redtoblackblewtopieces

We must use different forms , I use easycert and the agreed limitations section are at the bottem of section 3



Thanks, I've just checked out a sample, and your not wrong, it does seem that they have overcomplicated the most basic of the model forms.

I suppose you get what you pay for!

Edited: 27 July 2013 at 10:16 PM by weirdbeard
 27 July 2013 10:27 PM
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redtoblackblewtopieces

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Overcomplicate or provide the right information- each to their own- from my part I believe certifcates should show the work you have done complies and is recorded as such and that the information is passed onto the next electrician following me and that there is a direct link between extent of works covered and limitations,as an example.. extent of works covered might read extend circuit 2 final ring circuit to install additional three twin sockets under lounge bay window...limitations might read insulation resistance and end to end continuity tested for complete circuit but R1+R2,Zs ,RCD trip times and polarity only tested on new sockets.I know there is a school of thought that the circuit and every socket on it should be tested but for minor works I don't think this is needed.
Kevin

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 28 July 2013 11:02 AM
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leckie

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The agreed limitations bit on easycert is not on the BS7671 model certificates, it's just something they have decided to add on. I'm not sure I'm too keen on adding bits to the model forms, like number of points served on circuit schedules for example.

Could be useful though, as in the example Kevin gave. Also as the OP pointed out, it's not always practical to carry out a test between live conductors on an existing circuit, so a note could be made to point out that the line to neutral value of IR refers only to the additional work.
 29 July 2013 10:08 AM
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tillie

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Hi , very good question.

What I tend to do is try and test the whole cct where possible ie , take off consumer unit / distribution board cover and see if the neutral is indentifiable and whether the loads can be disconnected or removed.

If this is all easy then I will test the whole cct. This includes the new cct connected onto the old.

In most cases it is impossible to locate and disconnect all loads so I will join L and N together and test to earth and put this down in the limitations box which is included on the Niceic Meiwc.

In a few cases it is difficult to locate the neutral for the cct if they do not correspond with the fuseboard numbering which means you cannot IR test the cct .

So again you either have to be a fool and walk away from the job ( which I have had to previously do on a number of occasions when I could not find or was unable to gain access and confirm bonding conductors ) or test your new section of wiring with the cpc connected to the existing ccts earth.

Regards
 29 July 2013 05:38 PM
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weirdbeard

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Originally posted by: redtoblackblewtopieces

Overcomplicate or provide the right information- each to their own- from my part I believe certifcates should show the work you have done complies and is recorded


Hi kevin, compared with the BS7671 model form, it's definitely overcomplicated...how about cable type and reference method? Is that refering to the existing circuit, your new bit only or the whole lot combined.or is that another limitation?

Link for selecting example of 'easy cert' mwc :

http://www.tysoft.co.uk/easycert_certificates.htm
 29 July 2013 06:42 PM
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WalkersWiring

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I use the iCertifi documents, and their MWC has an agreed limitations box that I find very useful. Overall, I could pick quite a few holes in the iCertifi documents, but they are a work in progress and are being continually updated. They are very good value & have a professional appearance, but mostly they are extremely convenient. Whilst this is drifting away from the OP somewhat, I have to say that I don't see how an agreed limitations box over complicates a MWC - if you don't like it don't use it, but better to have the choice IMO...

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Jerry

The bitterness of poor quality lasts long after the sweetness of a cheap price...
 29 July 2013 06:45 PM
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redtoblackblewtopieces

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The new work is covered by the mwc , so cable type and reference method would be from the new work-think the requirments for 30mA rcd protection in domestics and new cable types like earthshield to BS8436, can you not see a situation where it might be advantages to record such details ? The model form dosent show a need for this or for the BS(EN) number of an rcd if present but just because a form does its hardly overcomplicated , but then I have been using these make of forms for about five years.
Kevin

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 29 July 2013 06:58 PM
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OMS

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LoL - whatever happend to that quaint, old fashioned idea of extending existing circuits in a cabling type and installation method to reflect the original design intent - ohh I know, that's why I see so much bloody T&E slung over ceilings and just meandering in and out of conduit boxes with the lids left off and those nice wago connectors on display for all to see -

Regards

OMS

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Failure is always an option
 29 July 2013 07:24 PM
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WalkersWiring

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Are you saying you're supposed to replace conduit box lids??

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Jerry

The bitterness of poor quality lasts long after the sweetness of a cheap price...
 29 July 2013 07:30 PM
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WalkersWiring

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Maybe that's what the agreed limitations box is actually for - "conduit box lids left off & randomly scattered..."

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Regards -

Jerry

The bitterness of poor quality lasts long after the sweetness of a cheap price...
 29 July 2013 08:19 PM
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OMS

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'Fraid so Jerry - I know it'll come as a shock to some - they'll be even more shocked to learn that defying gravity isn't in the product standard for T&E either

Regards

OMS

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 29 July 2013 09:19 PM
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leckie

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Your just being fussy OMS
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