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Green Building Bible, Fourth Edition
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    • CommentAuthorMike1
    • CommentTimeDec 16th 2020 edited
     
    Although the main solution has been to mandate the use of metal enclosures - see 'Enhanced Fire Safety from Consumer Units' at https://www.beama.org.uk/resourceLibrary/enhanced-fire-safety-from-consumer-units.html - the problem was the increase in consumer unit fires, partly caused by poor workmanship.

    Worth reading the best practice guide at https://www.electricalsafetyfirst.org.uk/media/1258/consumer-unit-connections.pdf
    • CommentAuthorphiledge
    • CommentTimeDec 17th 2020
     
    Quoting from a previous page doesnt seem to work for me, but in response to DJH's comment on RCBOs.......

    Adding an RCBO would give a single circuit RCD protection but leave everything else in the CU without protection, assuming a CU without any existing RCD protection.

    If you start adding RCBOs for all circuits then it gets expensive very quickly and takes up alot of cabling space. A CU full of RCBOs is a better solution than dual RCDs as it gives much better discrimination if theres a fault, but that comes at quite a cost
    • CommentAuthorEd Davies
    • CommentTimeDec 17th 2020 edited
     
    Posted By: philedgeQuoting from a previous page doesnt seem to work for me…
    It doesn't work for anybody. The workaround is to quote any arbitrary fragment of text from the current page, copy and paste the text to be quoted from the previous page (opening the previous page in another tab, of course) then remember to change the name of the person being quoted. Actually, change the name of the person first to be sure.

    Also, for anybody who doesn't realise this, you can quote only the relevant part of somebody's post by selecting that text before pressing the quote button. It's much easier for others to follow what's going on if only enough is quoted to make the context of the reply obvious. However, there's a possible gotcha here: if you select some text from one post then press the quote button of another (e.g., if you're quoting from near the end of a long post then press the quote button at the top of the following post) you'll get the selected text but attributed to the writer of the post with the quote button. E.g., this is misattributed:

    Posted By: philedgeWorth reading the best practice guide at
    •  
      CommentAuthordjh
    • CommentTimeDec 17th 2020
     
    Posted By: philedgeAdding an RCBO would give a single circuit RCD protection but leave everything else in the CU without protection, assuming a CU without any existing RCD protection.

    Yes, of course, but I think it does meet the regs without buying a new CU?
    • CommentAuthorphiledge
    • CommentTimeDec 17th 2020
     
    As I understand things that would meet the regs, as in providing protection to a circuit being modified, but definitely not best practice to leave the rest of the house without RCD protection, if thats the case.
    • CommentAuthorArtiglio
    • CommentTimeDec 17th 2020
     
    The current ideal is the use of rcbo’s on every circuit , but this soon gets expensive. So the current trend is towards “high integrity consumer units” where you have a mix of circuits with rcbo’s and the rest protected by one or more rcd’s, as deemed necessary by the installer/client.
    Arc detection is pretty recent and extortionately expensive for the latest perceived safety issue, but no doubt in time they will become the norm.
    I’m a landlord and 5 years ago an EICR ( electrical installation condition report) cost just under £100 for an installation with upto 5 circuits. Just been quoted for next years retests and that’s jumped to £260 plus vat, hard to see the increase is little more than being able to name your price as its now a legal requirement to have an EICR.
    The days of getting a new consumer fitted for around £300 are well gone. I was considering upgrading a few alongside the EICR but at £600 a piece , i’ll wait until my existing units are declared unsafe ( currently they have rcd protection to power circuits and most have unprotected lighting circuits ( the theory when they were installed 2002-4 was that it was more dangerous plunging a house into darkness ( people stumbling about looking for cu etc in dark) if a bulb blew than any likelihood of an electrical injury from a lighting circuit).

    Be interesting to see what the next move will be , no doubt parliament will be watching how the scottish parliaments decision to make fire and co alrms in private houses goes down. Though not to do so is not a criminal offence and enforcement is by local authorities.
    • CommentAuthorphiledge
    • CommentTimeDec 17th 2020
     
    Might be worth changing the CU yourself at <£100 and getting your building control to inspect and certify the CU/installation. Seems to be £100's cheaper than what your getting quoted.
    • CommentAuthorArtiglio
    • CommentTimeDec 17th 2020
     
    <blockquote><cite>Posted By: philedge</cite>Might be worth changing the CU yourself at <£100 and getting your building control to inspect and certify the CU/installation. Seems to be £100's cheaper than what your getting quoted.</blockquote>

    My local building control won’t do it ( they are not qualified) instead they ask you to find your own or use their nominated electrical contractor to inspect/test and certificate. This used to be an option about 10nyears ago that worked, but these days its an option that grow arms and legs , electricians are wise to the manoeuvre and so test to the nth degree as they have no pre installation readings to compare the new unit to.
    Someone i know recentlysold a house where the consumer unit had been changed but no paperwork, they got round it by paying for indemnity insurance, which cost little and covered a few other bits at same time.
    Its really a case of people being forced to use “ professionals” with the associated costs. Like for like replacement is now all a “ competent “ person can now do.
    Which is all very well, but can’t help thinking more good would be done by ensuring that dodgy electrical appliances don’t get into the country. Apparently knock off chinese chargers are a common source of electrical fires along with people using damaged appliance leads and ocerloading extension blocks, usually behind the telly.
    • CommentAuthorEd Davies
    • CommentTimeDec 17th 2020
     
    Posted By: Artiglio( the theory when they were installed 2002-4 was that it was more dangerous plunging a house into darkness ( people stumbling about looking for cu etc in dark) if a bulb blew than any likelihood of an electrical injury from a lighting circuit).
    That's something that's changed, of course - it's usually incandescent bulbs which trip RCDs on failure, LEDs not so much AFAIK, so having far fewer incandescents around swings the argument towards having RCDs on lighting circuits.
    •  
      CommentAuthordjh
    • CommentTimeDec 17th 2020
     
    Posted By: ArtiglioSomeone i know recentlysold a house where the consumer unit had been changed but no paperwork

    The house next to us recently changed hands. The new owner's been ripping out all the wiring and plumbing, which didn't surprise us too much since it was looking pretty tired. But today he told us that (a) he's an electrician and (b) he bought the house with an up-to-date electrical cert but as soon as he got in he realized it was dangerous. Hence ripping it all out! So much for the value gained by paying for certs.
  1.  
    Ed:>>>> " incandescent bulbs .... trip RCDs on failure, LEDs not so much AFAIK"

    AFAIK: LEDs, computers, induction hobs and all the other stuff with switched mode power supplies, apparently might not be compatible with traditional 'type AC' RCDs - the capacitors/inductors charge and discharge causing the current in L and N not to instantaneously match - the mismatch is detected as a 'leakage' current which has a much higher frequency than the RCD is designed for. The leakage current causes heat in the RCD sensing CT and it might not act when there's a genuine leakage through somebody.

    There are bigger versions of this issue in heat pumps, washing machines, etc with variable speed drives and big capacitors. I now understand why our ASHP used to trip the RCD intermittently!

    This could favour using RCBOs, so each type of circuit can use the appropriate type of RCD, and if the EV charger trips its RCD the house lights won't go out.

    https://professional-electrician.com/18th-edition/doepke-consumer-units/

    Edit: example given in link is to put the lighting circuits on individual 'type A' RCBOs, then group the living/bedroom socket circuits on a shared 'type A' RCD, and group kitchen/utility/heating circuits on a shared 'type F' RCD
  2.  
    RCD types per the 18th edition:

    Type AC - the kind found in most existing CUs - only for resistive loads like kettles and immersions

    Type A - also for switch mode stuff such as LEDs, dimmers, computers, induction hobs

    Type F - for the above and for variable speed loads such as heat pumps and washing machines

    Type B - for all the above and for PV inverters and some EV chargers

    https://electrical.theiet.org/wiring-matters/years/2019/77-september-2019/which-rcd-type/
    • CommentAuthorRex
    • CommentTimeDec 23rd 2020
     
    Gentlemen,

    Never thought my basic question would start such a debate. I have been investigating CU's and am p***ed off that even the smallest is considerably larger than the existing, so the wall will have to have a few bricks removed. That turns what should be a simple job into a much bigger job.

    So I guess I will have to buy whatever is available and have a lot of redundant space. I cannot seen any future owners wanting more than there already is, it is a basic maisonette; future owners are unlikely to be electric car owners, but frankly, that will be their problem.

    My solution to making good after removing a few bricks, will be to cover the work with a piece of Fermacell into which will be a cut-out for the CU to fit through. Basically, make a 'feature' of the CU rather than try to hide it flush with the wall. This will be less disruption for the tenants.
    • CommentAuthorphiledge
    • CommentTimeDec 23rd 2020
     
    Its fairly standard practice for electrical back boxes to be set into brick work so your spark shouldnt have a problem removing a strip of brick work along the top or bottom to fit a taller modern CU.

    If reworking the brickwork is too big a job, theres nothing to stop you fitting a section of DIN rail within the existing enclosure and mounting RCDs/MCBs/RCBOs onto the DIN rail. Youd need to get somone to fabricate a steel cover. All the components needed are available separately but if you are truly on a budget then buy a plastic dual RCD CU off ebay and build the components into your enclosure.
    • CommentAuthorEd Davies
    • CommentTimeDec 23rd 2020
     
    Posted By: Rexfuture owners are unlikely to be electric car owners,
    Are the existing occupants car owners?

    Posted By: philedge…theres nothing to stop you fitting a section of DIN rail within the existing enclosure and mounting RCDs/MCBs/RCBOs onto the DIN rail. Youd need to get somone to fabricate a steel cover.
    IIRC, enclosures (for all connections, not just switchgear) need to be to a certain BS.
    • CommentAuthorowlman
    • CommentTimeDec 23rd 2020
     
    The height of modern CUs seems to be the problem in your case Rex. This Wylex 5 way unit almost fits the bill size wise if mounted on its side, H 261 x W 188 x D 121, don't know if that's permitted, though, I can't see why not.

    https://www.electricpoint.com/wylex-5-way-main-switch-consumer-unit-100a-dp.html
    • CommentAuthorRex
    • CommentTimeDec 24th 2020
     
    Thanks for the link; yes, I had found that CU and yes, it does more or less fit the dimension with one major issue!

    My current one is horizontal, this one is vertical. So no other option than to remove some bricks.
    • CommentAuthorEd Davies
    • CommentTimeDec 24th 2020 edited
     
    Posted By: RexSo no other option than to remove some bricks.
    What about the option owlman suggests? Lots of boat and US domestic circuit-breaker panels have the breakers going left/right rather than up/down. The cover relies on direction of the gravity or acceleration vector, though.
  3.  
    Different parts of the regs apply on boats, which are the only installations where the acceleration vector is worth considering.... That CU will not be fire containing unless the door is held shut by gravity.

    Posted by me on the previous page: "ask the sparky to do any work on extending the cavity while live meter tails are dangling into it”. What did the sparky advise you?

    For the forum's further consideration: new buildings CUs are required to be 'accessible', so at the same kind of height as light switches - no longer allowed high above the kitchen cupboards or up above the coat rack, where you'd need steps to test the RCDs. (Edit: though I see there's a mess of different requirements and interpretations between different parts of the UK)
    • CommentAuthorphiledge
    • CommentTimeDec 24th 2020
     
    If you look at commercial/industrial distribution boards, components are routinely mounted in vertical rows rather than horizontal.

    In terms of enclosure standards its perfectly acceptable on refurbishment projects to fit new components in old enclosures. The existing enclosure will likely have complied with any relevant BS standards when it was new and I cant see much changing in the spec of a tin box. Relvant issues like corrosion resistance, earthing, IP rating are just as applicable now as they were 30 years ago, for the enclosure.

    A new main switch and 3 RCBOs will fit nicely in the existing enclosure with a new lid. Plenty of space for an EV charger supply if needed in the future😊
    • CommentAuthorowlman
    • CommentTimeDec 24th 2020
     
    WillInAberdeen 2 hours ago edited quote
    ... That CU will not be fire containing unless the door is held shut by gravity.

    Does it actually say that or is that your interpretation? My Hager metal CU has a sideways glazed door that has a small turn catch.
  4.  
    Sorry, I was referring to the Wylex one, although AFAICS the current Hager range are the same design, with a metal flap that falls over the plastic mcbs.

    "The non-combustible enclosure or cabinet must provide a complete envelope (for example, base, cover, door and any components such as hinges, screws and catches) as necessary to maintain fire containment."
    • CommentAuthorphiledge
    • CommentTimeDec 24th 2020
     
    Standard commercial dist boards are almost always vertically populated with components and have a side hung doors that arent self closing. AFAIK the regs apply equally to those boards, unless theres some specific domestic requirements??
    • CommentAuthorEd Davies
    • CommentTimeDec 24th 2020
     
    Posted By: philedge…unless theres some specific domestic requirements??
    There are specific domestic requirements, see further up this thread.

    However, the point here is that the specific 5-way Wylex consumer unit that Owlman referenced relies on gravity to hold the cover in position. If it was mounted sideways then it'd need to be modified to latch the cover closed to meet the relatively-recent BS7671 for domestic switchgear enclosures but then it would no longer be certified to the other BS for all wiring enclosures.
    • CommentAuthorRex
    • CommentTimeDec 26th 2020
     
    Ho Ho Ho gentlemen,

    As much as I would like to utilize the horizontal hole, I would not do so, so a vertical CU with gravity flap is what it will have to be.
    • CommentAuthorphiledge
    • CommentTimeDec 26th 2020 edited
     
    Posted By: Ed Davies<
    If it was mounted sideways then it'd need to be modified to latch the cover closed to meet the relatively-recent BS7671 for domestic switchgear enclosures but then it would no longer be certified to the other BS for all wiring enclosures.


    Theres plenty of wiring enclosures that have a mechanical means to hold the door closed that dont rely on gravity including all manner of catches, locks, handles, screws etc and are claimed to be compliant with EN 62208

    Is there a section in the wiring regs that specifically states domestic CUs must have a gravity closed cover??
    • CommentAuthorEd Davies
    • CommentTimeDec 26th 2020
     
    Posted By: philedgeIs there a section in the wiring regs that specifically states domestic CUs must have a gravity closed cover??
    No, AFAIK there isn't and I didn't say it wouldn't be compliant, I said it wouldn't be certified to be compliant on the assumption that any modification would invalidate the certification.
    •  
      CommentAuthordjh
    • CommentTimeDec 26th 2020
     
    My CUs were installed just before the amendments came in, and under regs that preced the amendments by some years. So they are plastic, not metal. They are installed at part M heights though because that seemed to be sensible and may have been required by Lifetime Homes or some other standard we were trying to meet (don't remember exactly). What lets me live with them at that height is that the front covers are hinged at the bottom and flap down, so I can see the MCBs etc when I'm standing up. They're held closed by latches.

    The idea of having to stand there and hold up the front cover whilst I look at the innards and do whatever else I'm doing fills me with horror. Who on earth thought that was a good idea, even for a person in a wheelchair?
    • CommentAuthorphiledge
    • CommentTimeDec 27th 2020
     
    Posted By: djh

    The idea of having to stand there and hold up the front cover whilst I look at the innards and do whatever else I'm doing fills me with horror.


    And if its an intermittent fault on a lighting circuit, youll be doing it with a torch in your mouth😁
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