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Completing MWC properly as DIY'er

Discussion in 'Electrics UK' started by McKenna32, 30 Jun 2019.

  1. McKenna32

    McKenna32

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    Hello folks,

    I’d like to do some non-notifiable minor electrical works on my home as part of some building work we’re having done and I want it done properly recorded on MWC. I want to DIY it. I want to be able to stand by my work and produce documentation if it’s ever required (selling house, LABC approval of current building work*, etc.)

    Although I have some relevant background**, I have no formal electrician/building regs qualification.

    I figured this seemed like a generic enough situation and I couldn’t find straight answers to my questions elsewhere, so thought I’d go fishing…

    Works are, mainly in the kitchen (just so it’s clear this is non-notifiable):
    • moving and extending cooker radial
    • moving and adding sockets & fused spurs to ring main
    • adding lights & switches to existing lighting circuit
    i.e. new fixed wiring all over the gaff, but no changes at CU. CU includes 30mA RCD that covers all circuits (TBC) – so I’m assuming I’m good to leave that well alone (as I should as DIY’er)

    My plan is to get an EICR from a sparky after just as belt and braces check of the whole place, but I appreciate that’s a different thing to MWC and does not negate the legal requirement for it.

    I’d like to check a few things and figure this is the right place for that.
    • There is no legal requirement, other than to be a “skilled person”, of which there is no strict or formal definition (i.e. BS7671/partP quali or otherwise), in completing & signing off a MWC. Can I please check this is this correct and uncontentious?
      • What I need to do is satisfy myself that I have the tools and knowledge necessary to put my name to the work and (practically) permanently imagine myself standing in the dock defending it is probably a good attitude.
    • Regarding the testing, which is a big chunk that many DIYers seem to miss off, I’m poised to spend a couple £00 on testing kit, but before I do could I please check:
      • I don’t need to have full logged history of the tools involved and I just need to trust/calibrate them to my satisfaction (i.e. I can borrow them from, say, work, or hire them – if that’s a thing, or borrow from a trusted friend)
      • If I need better traceabiity is it a reasonable request to get an electrician to make just these measurements (perhaps best as an EICR as suggested here to give a paper trail) and copy into the MWC with my name on it.
    I don’t pretend to know the building regs or part P in great depth right now but intend to buy 18th OSG and will ask if in doubt. My kids will be growing up in this house, and I’ll know a lot more after finishing it off, let’s put it that way.

    I know I’m unlikely to find a spark to just do the test & MWC once I’ve done all the install, so once I’m committed I’m all in to the end.

    Any sources you cite would be much appreciated, but if not just a trail of breadcrumbs will do! Happy to be proven wrong also.

    Thanks in advance for any advice, and my apologies if this is a repetition of prior questions (I have searched for a good few hours on this now to build up the above picture)

    Cheers,

    Al

    *which my builder assures me will happen even though the electrical works are non-notifiable – they’ll be on site and can see the evidence for electrical work, so will ask for MWC.
    **Mainly in >60V traction systems which is utterly different regs-wise of course but still an electrical fire and a hazardous exposed voltage are identical problems resulting from shoddy work (of which I have some experience from when I was an unsupervised young player)
     
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  3. EFLImpudence

    EFLImpudence

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    Firstly there is no relation between Minor works and whether Notifiable or not.

    However, there are so few notifiable things now in England that you might need an Electrical Installation Certificate to record all the necessary details even on non-notifiable work.

    A start -
    https://www.flameport.com/electrical_testing/index.cs4
     
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  4. jelliottelectrical

    jelliottelectrical

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    The problem is, if you don’t know what you are testing then you might as well not certify. The only thing with the test equipment you need to record on the certificate is the make, model and serial number.

    However, do you know what you should be testing, and what values you are looking for? And whether these values are within limits, and are correct for the work carried out?
     
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  5. McKenna32

    McKenna32

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    Thanks for the replies!

    Makes sense, adding a light fitting in a bathroom, that sort of thing

    Interesting point. Will read the link. On a quick look at the cert it might require the CU to be opened to fill in some fields which is clearly not DIY-able legally.

    "what I should be testing" = a pretty good but probably not complete idea. "what values" = not yet, no. First trying to figure out if it's worth learning - i.e. can I do it legally and at reasonable cost, then if so learn what the right values are. No point spending the money on the tools and spending the time trawling the regs/forums/'tube if I legally can't produce the paperwork, (I'd just call an electrician in!).

    Cheers

    Al
     
  6. McKenna32

    McKenna32

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    Watched this - seems clear this is not a form you can fill in as DIYer, but confirmation appreciated?

    Does seem like I should be able to do this under minor works though from what I understand so far. The complete list of what I plan to do:

    Existing ring main 32A cct
    (re/)moving sockets
    Adding sockets – some into Kitchen cupboards/service gaps
    Some new fixed wiring for above
    new fused spur for under-cabinet lighting
    moving fused spur for an existing outside light feed​
    Existing radial 32A cct (cooker)
    extending - new fixed wiring from new 60A jct box
    Install new 45A isolator (may/not be required TBC)
    moving cooker jct box (induction hob & oven splitter)​
    Existing lighting 6A cct
    New switched supplies from existing circuit
    New light fittings
    Outside lights installation (cable straight shot inside->outside)​

    I suppose that would be best recorded on 3 MWCs for clarity.

    Cheers,

    Al
     
  7. jelliottelectrical

    jelliottelectrical

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    To save filling out the paperwork I would normally do this on an EIC just for the amount of work but 3 Mwcs is totally fine too. I see no reason if you are competent enough to fill out an Mwc, that you couldn’t fill out an EIC

    It is important to get it right though, I was once called upon after a major fire (17th century farmhouse, 70% gutted by an electrical fault in the loft, which had been insulated by the farmer sometime in the past with straw!) as I had been the last electrician to work on the property (around a year before). My certificate (mwc for fitting a bathroom extractor) was heavily scrutinised as the fire started in the bathroom. Fortunately they could find no fault with my work (more evidence that the immersion heater in the bathroom had been the cause of the fire) and I had also used the comments section on the form to detail a few existing issues with the generally poor state of the electrics in the property.
     
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  8. ericmark

    ericmark

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    I can apply to the LABC and pay their fee and do all the electrical work I want on my house. The only thing I can't do is remove a DNO seal, so it may require an isolator fitting so I can disconnect the supply. (Most would not bother, they would draw the DNO fuse, but looking at what should be done.)

    However the LABC are reasonable for site safety once you pay their fee, so they have to assess if you can safely do the work, and if you can't show you have the skill, then they can refuse permission to do work they feel you don't have the skill to do.

    With non notifiable work, there is only the health and safety at work act that stops you doing some work, since at some time you will have people at work in your house, the house must be safe for them, be it a social worker, policeman, dust man, or double glazing salesman, at some time we will have some one at work in our house. Not sure about the thief, is that work?

    Of course you want the house safe for your family, but the IET/Bsi wiring regulations BS7671 is not law, although it can be used in a court of law. Most will regard it as law, for a scheme member it is law, as he has a legal binding agreement with the scheme provider to follow BS7671, but if I want to fit German sockets in my house I can, but a scheme member could not fit them as they don't comply with BS7671.

    So test equipment first, as I found to my cost, traceable records mean nothing, as when it comes to shove, they can't 90% of the time actually trace them, this includes compliance certificates, I am sure they could be found if the HSE demands them, but council told me would take 3 months, so forget traceable, what you want is to compare with known supply or similar to show they are reasonably accurate, I have two insulation testers and if they show same result, then highly unlikely either is faulty. The supply to house has been recorded at 0.28Ω loop impedance, if the meter shows that figure at the supply then unlikely it is faulty. We are taught how to prove dead using a proving unit to show before and after the meter is sound, the same in a way applies to all other test equipment, I had a socket at home I knew the loop impedance for, and I would regularly test it, I don't want to find on a yearly calibration my meter is out, and I need to re-test everything done in last year. It is just common sense, to test once a week even if you don't record it.

    You can buy an insulation tester for around £35, and a very simple plug in loop tester for around £45 with go/no go lights, but the latter will not give the results needed to fill in a minor works, the meters required for that will cost around £300, same for testing the tripping times of a RCD, can't really measure 40 milliseconds with a stop watch.

    Now the forms say enquiry is a valid method to find the ELI of the supply, and you say your getting an EICR done on completion, so why not simply copy the results onto your MWC if your so inclined?

    To be frank I have seen many a MWC and EIC where they have figures which don't seem to match, it says the property has a TN-C-S supply, the ELI is 0.30Ω and the PSCC is 1.2kA how? if the ELI is correct than PSCC will be 767 amp, it is simple ohms law. And so many forms will not stand close scrutiny, which I suspect is why the loop readings for each socket are not recorded.

    But electrics is all about maths, so a B rated MCB is designed to trip at just above its rating for thermal release, and between 3 and 5 times rating for magnetic release, so a B32 MCB will trip at 5 x 32 = 160A so simple ohms law 230/160 = 1.4375Ω give 5% margin to allow for volt drop so 1.37Ω corrected to two decimal places. Volt drop is not as easy, as there is a complex formula to give correction figures, and one has to decide what to use as the design current with a ring final, most consider 20A centre and 12A even spaced, so use 26A as the design current, so allowed 5% volt drop = 11.5 volt so again ohms law, so 0.44Ω plus the incoming impedance so around the 0.94Ω mark, I don't think many worry about volt drop.

    There are tables in the BS7671 to help you, but you need to understand what you are testing, if volt drop is 6% instead of 5% it will not make much difference, but if the impedance is just slightly too high, then the magnetic part of trip will not work, so you jump from a 0.02 second disconnection to 5 minutes, so there it is very important, with the old fuse it was not so important, but ELI with RCD protection is not so important, but then the test results for the RCD are, and to test a RCD there are 6 tests, or 3 pairs of tests positive and negative for each test, and I have found the strain of a wire in the terminal can warp the device enough to make it fail, so if worked on, they need testing, and I don't mean press the test button.

    All the expensive test gear, will not find a borrowed neutral, it is such a basic rule, never borrow a neutral, yet again and again I find borrowed neutrals in the lighting circuits. I have even found electricians move a MCB from one RCD to another because the borrowed neutral was causing it to trip, OK stops it tripping, but still a borrowed neutral. Can you work out why? if not, do you think you should do the testing?

    So two reasons to test, one to find if there is spare capability before adding to a circuit, the second to test if safe after doing the work, often we take a chance with first, and only test after, if we find it fails to reach 1.37Ω for ring final, then fit a smaller MCB, so get it tested once finished and then fudge the paper work by copying the results to your MWC.
     
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  9. JohnW2

    JohnW2

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    What makes you say that?

    As I understand it, anyone adequately competent to do it (and the work) and having (or having access to) the equipment necessary to undertake the required testing (and with an understanding of how to use that equipment, and interpret the results) can fill in an EIC, regardless of their occupation, 'status', training or qualifications.

    Kind Regards, John
     
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  11. EFLImpudence

    EFLImpudence

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    It depends what you mean by 'can'.
    Anyone may (is allowed to) fill out any certificate. Obviously if you do not know how to do the tests or what the numbers mean or do not have the equipment then you cannot do it.

    You keep saying minor works (certificate) as if it does not require as much knowledge to complete. This is not the case.
    Minor work refers to the work being minor. The certificate just includes fewer items than an EIC. You could still use an EIC and have lots of N/As.
    It is more correctly a Minor Electrical Installation Work Certificate - the Electrical Installation Work being minor; not the Certificate.


    Ok. If you know how to do all that then, fine.​

    It doesn't matter. It depends how much testing you think is required or are able to do.
    If you test for things which are not included on a MEIWC then you will need an EIC.
    It is the results which are important; not the piece of paper you use.
     
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  12. flameport

    flameport

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    There is no law that prevents DIYers or anyone else from opening a consumer unit, or installing one, or making alterations to one.
     
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  13. McKenna32

    McKenna32

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    Evening all,


    Firstly thanks for the detailed and considered responses. Please understand I’m coming at this from a (deliberate) perspective that seems to be prevalent among DIY’ers - “Not notifiable? Pass me that screwdriver and hold my beer”


    Nope not at the moment, but glad borrowed neutral was on the youtube "to watch" list anyway! I certainly do not know everything I need to know right now so would be learning in real-time (otherwise I’d be getting on with it! )


    Yep that's exactly the approach I'd have started with :)


    Something about needing to record the CSA of conductors entering the CU. I can dig them out the wall or look at the meter and have a guess given their insulation OD but I can’t do what I’d consider “proper” which is get hold of the loose end and measure/count the strands. Maybe inferring copper CSA from cable finished OD is normal practice – I don’t know…


    Sorry, I’m being unclear. I’m coming at this from the starting perspective that “all this electrical paperwork stuff” could only be legally completed by qualified electricians. The revelation that started this all off is that I “can”/(“may”) fill in a MEIWC myself if I have the tools and knowledge. As above I still thought EIC was off the cards, but sounds like that’s distinctly on them. I understand both MWC and EIC require populating with test data that is non-trivial to obtain.


    So my feeling right now is that whilst I’m pretty sure I’m able to do a good job of the install, the testing side is a potential can of poo I’ve no idea how to gauge the magnitude of


    I’ve also not managed to come up with a source for a proper RCD tester, which will be about £300 as you say @ericmark, not least the value of my time learning to use it properly, is quickly going to vastly exceed the cost of getting a sparky in assuming they let me do the dusty stuff as it’s not actually a massive job.


    Still plan to put an OSG into the amazon basket so I’ve got a better run-up at this next time. A lot of this hinges on what information is actually in there.


    Anything to add, though, for the record?
     
  14. McKenna32

    McKenna32

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    Oh that's interesting, another assumption potentially up in flames....
     
  15. Risteard

    Risteard

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    Minor Electrical Installation Works Certificate, actually.
     
  16. EFLImpudence

    EFLImpudence

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    Factually correct in what BS7671 states, thank you.

    However, I'm not entirely sure what "Minor Electrical Installation Works" means nor if it makes sense.

    Is just one job MEIWork and more than one MEIWs?

    I have done two electrical works today ??? Perhaps if you had written two plays - Two works of Shakespeare.

    Isn't a "works" a factory or something similar - or a third person singular verb?

    Is there perhaps a missing apostrophe? No, it's not an "Electrical Installation's Certificate.
     
  17. JohnW2

    JohnW2

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    Indeed but, at least in the minds of some 'authorities', there is another meaning (we are, after all, all fairly comfortable with "road works" etc.) ...

    upload_2019-7-1_21-1-26.png

    Kind Regards, John
     
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