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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorRex
    • CommentTimeDec 2nd 2020 edited
     
    What ho one and all,

    I have a two bedroom maisonette that we rent out. I has a five yearly electrical test (passed yesterday) but the consumer unit probably dates from when it was built and is just three wire fuses plus a main wire and a easy to access main switch. It has been suggested that it would be a good idea to up-date it.

    The current unit is virtually flush mounted and as space is limited in the entry area (about 5 feet x 5 feet), I don't really want anything protruding. The current recess is 300mm x 180mm approx.



    But any recessed consumer unit that I can currently find is considerably larger (https://www.denmans.co.uk/den/root-category/Distribution/Consumer-Units-%26-Devices/Consumer-Units/Curve-14-Way-Dual-RCD-High-Integrity-Flexible-Consumer-Unit-White/p/2500912029)

    Are there any simple, flush mounted consumer units available that only offer a few (3?) circuits?

    Thanks and toodle pip
      ConsumerUnit.jpg
    • CommentAuthorowlman
    • CommentTimeDec 2nd 2020
     
    • CommentAuthortony
    • CommentTimeDec 2nd 2020
     
    looks like Wylex mcb's would fit it to me
    •  
      CommentAuthordjh
    • CommentTimeDec 2nd 2020
     
    Why not just make the recess a bit bigger?
    • CommentAuthorphiledge
    • CommentTimeDec 2nd 2020
     
    Theres no visible RCD and if theres not an external RCD youd be crazy to rent the place out. Did the spark that did the inspdetion know it was a rental property?

    Pretty sure you can buy MCB units to replace the old rewirable fuses, but for a rental property you need to modernise ASAP.
    • CommentAuthorEd Davies
    • CommentTimeDec 3rd 2020 edited
     
    Is the one Owlman suggests OK for residential property? My understanding was that there was a requirement for non-flammability which, the way the rules were written, meant it had to be metal; have non-metal boxes been approved now or is that unit only OK for non-residential use?

    Correction: I wrote “for non-residential use or in garages, etc” but it seems metal consumer units are required in domestic garages, even detached ones:

    https://www.beama.org.uk/resourceLibrary/technical-update-enhanced-fire-safety-for-consumer-units.html

    More generally, this looks like a useful resource:

    https://electrical.theiet.org/bs-7671/faqs/consumer-units-and-protective-devices-faqs/
  1.  
    I'm certainly not sparkily qualified but AIUI a new consumer unit will be to 18th edition, so will be made of steel.
    It will include arc fault and surge overvoltage gubbins, and space for either RCD or RCBOs. All this tends to make it bigger...

    Can you dig out a bigger recess with a board at the back, and mount a new CU onto the board?

    Looking ahead to the electrification of heat and transport, it's worth having lots of spare ways in the CU for future electric heaters, showers, car charger etc

    Edit to add: the installation needs to be 'designed' by the sparky who will sign it off - might be best to ask him/her to select the new CU, and to do any work on extending the recess while live meter tails are dangling into it..
    •  
      CommentAuthordjh
    • CommentTimeDec 3rd 2020
     
    Posted By: WillInAberdeenLooking ahead to the electrification of heat and transport, it's worth having lots of spare ways in the CU for future electric heaters, showers, car charger etc

    To be fair, I think the work to install any of those into Rex's maisonette would likely be so major that fitting a new larger CU at the same time would be lost in the noise. But yes, we have two CUs in our house to get enough ways, and another in the garage where the meter is.
  2.  
    Not clear what you mean - are you advising Rex to continue looking for a 3-circuit CU, or for a bigger one with spare ways?
    •  
      CommentAuthordjh
    • CommentTimeDec 3rd 2020
     
    I'm just saying I don't think it's worth Rex thinking about future electrification of heat and transport when deciding what size CU to buy. I've already suggested making a larger hole for the CU so it's up to him what he does.
    • CommentAuthorRex
    • CommentTimeDec 3rd 2020
     
    Gentlemen,

    Thanks very much for the thoughts. i was not proposing to buy the CU, just find one that will fit with the minimum disturbance to the wall. And since there is a recess, .........

    The sparkie who did the testing has done if for the past ten years, so I figure he knows what he is doing. It is not essential that the board is changed, just like the MOT advisories, it is a 'best advice.

    As for an RCD, certainly on the board, there is none, however, for any outside power requirements, below the board and not in the photo is a 13A socket with RCD facilities.

    I will ask the sparkie about plastic v. metal.
    • CommentAuthorphiledge
    • CommentTimeDec 3rd 2020
     
    The standard now is to have RCD protection more or less on on all circuits indoors and outdoors. If you look at current domestic consumer units youll do well to find one without an RCD, for all circuits.

    New installs and refurb/replacements need non combustable consumer units

    Its your choice if you want to run with rewireable fuses and no RCD, but for a rental property youd be mad not to have the protection an RCD offers.

    If your spark knows its a rental property and isnt making a song and dance about the lack of RCD, it might be worth getting a second opinion for your own peace of mind??
    • CommentAuthorRex
    • CommentTimeDec 6th 2020
     
    Don't think the sparkie is making a song and dance. He is a nice guy and I do trust him and his expertise. But I am happy to replace the consumer unit for a more up-to-date model.

    My main issue is that in the current location, a wall mounted unit will encroach into the entry area, which is already rather small. Hence a flush mounted unit.

    The alternative is wall mounted but higher up. That of course will mean some rewiring, and I don't know how easy it is to find and relocate the wires in the cavity without major disruption.

    This current fuse board is back to back with the meter, so the all the wires would have to be re-routed.

    I will ask him.
  3.  
    IMO get rid of the rewire-able fuses ASAP if it a rental property. If something blows the fuse there is no knowing what the tenant will rewire with - anything from a paper clip upwards. MCBs are a much better safer option. Oh and a RCD as well 'cos tenants do silly things!
    • CommentAuthormarktime
    • CommentTimeDec 6th 2020
     
    Here's an idea for you. Not sure why you need a metal casing, this unit is CE certified.

    Size 200 x 400 mm
      Consumer .jpg
    • CommentAuthorEd Davies
    • CommentTimeDec 6th 2020
     
    Posted By: marktimeNot sure why you need a metal casing, this unit is CE certified.
    Because putting a non-metal one in in this location would be a breach of the wiring regulations which would likely result in a lot of poo if there's an accident, particularly in a rental property. Just because something is CE certified doesn't mean it meets the legal requirements for all possible applications and it may well have been CE certified before the fairly recent change to require metal enclosures in domestic (residential?) accommodation.
    • CommentAuthorphiledge
    • CommentTimeDec 6th 2020
     
    You can use plastic CUs so long as they are in a none combustable enclosure ie a metal cabinet/cupboard. CE marking ensures compliance with EU safety standards but not necessarily with individual countries requirements ie UK wiring regs
    • CommentAuthorphiledge
    • CommentTimeDec 6th 2020
     
    Posted By: Rex

    This current fuse board is back to back with the meter, so the all the wires would have to be re-routed.


    If you open up the recess as has been suggested, you're likely to be able to fit a new CU without any rewiring. Its just a straight forward swap out with the opening slightly larger than it is now. Youve currently got what looks like the equivalent of a 9 module CU. A replacement 10 module CU will allow a main switch, 2 x RCD's and 4 x MCBs.

    Your sparky should be able to guide you as to whether your cables will be long enough without rewiring.
  4.  
    As I understand it, since earlier this year, new installations should now be to the 18th edition. In houses/flats this requires a non combustible case that can keep an electric fire contained inside it - this includes the flap on the front. You can still buy plastic units for use in garages sheds etc.

    All sockets/lighting/circuits must have RCDs, as they have for many years. There must not be bad consequences if the RCD trips and takes out other circuits (eg if a socket circuit trips the RCD and takes out all the lights). Some folk are interpreting this that each circuit should have its own RCD (RCBO).

    The correct type of RCD must be fitted on each circuit, to deal with eg switched mode LED lighting which does not have traditional resistive electric characteristics.

    You are now recommended to have arc fault detection (detects if there is dangerous sparking somewhere in the circuit) and a surge protection device (stops lighting strikes nearby damaging electronics).
    • CommentAuthorEd Davies
    • CommentTimeDec 6th 2020
     
    Posted By: WillInAberdeen: “You can still buy plastic units for use in garages sheds etc.”

    Only if they're domestic garages, sheds, etc, far enough away that fire won't spread from them to the house, see section 5 of the document linked here:

    https://www.beama.org.uk/resourceLibrary/technical-update-enhanced-fire-safety-for-consumer-units.html
    • CommentAuthorborpin
    • CommentTimeDec 16th 2020
     
    Electrical regs have got out of hand IMHO. The regs are an industry to force consumers to part with cash and line the pockets of the 'professionals'.
  5.  
    A quick dip into the tech. bulletin shows
    " These new and changed regulations will apply to all Electrical Installations designed after 30th June 2015 (see Note 2 below)"
    So IMO if you are not designing but doing maintenance / repair the regs. don't apply.

    Also from the document
    "There is no published definition for "non-combustible" that aligns with the intent of
    Regulation 421.1.201. Ferrous metal, e.g. steel, is deemed to be one example of a non-combustible material that meets the intent of the regulation."

    So steel is one example - how about flame resistant plastic, flame retardant plastic, non flammable plastic or inherently self extinguishing plastic as other examples?
    •  
      CommentAuthordjh
    • CommentTimeDec 16th 2020
     
    Posted By: Peter_in_HungarySo IMO if you are not designing but doing maintenance / repair the regs. don't apply.

    I don't think that's correct in the case of a consumer unit. I believe it's notifiable work that is carried out under the current regulations and results in a new system that has to be tested and certified in accordance with current regulations. I can't quote chapter and verse unfortunately but I would urge anybody contemplating such work to check carefully.
  6.  
    Hi Peter, I believe that was the 17th edition 3rd amendment from 2015. The 18th edition applies from 2020.

    The requirements for fire-containing CUs came in with the 17th Ed amendment, so the manufacturers have been selling the enclosures since then. They mostly seem to have chosen steel. To contain a fire, the box needs to not melt, so that would need a very fancy kind of plastic, so steel is probably cheaper. It obviously has a good earth.

    Ours was installed with big cable knockouts in the back into a service void, so Im not counting on it to keep a fire contained for very long :-(

    AIUI the 18th Ed changes are about choices of RCD/rcbos/AFD/SPD, so affecting the layout rather than the material of the case.

    A sparky doing maintenance has to make sure all his/her own work complies with regs, such as installing a CU. They don't have to bring existing installations up to the newest standard if they are not modifying them, but they do have to make recommendations on their certificate. If there were an accident and it came out that the landlord had ignored the recommendation, then the insurers or an injured tenant or tradesperson would use that in their claim, so Rex is wisely getting a 21st century CU fitted!

    Testing the new CU may expose other hidden faults which may need to be fixed. In a previous house it was found that a mummified mouse had its teeth embedded in a cable under the floor, it had to be removed before the new RCD would stay closed...
    • CommentAuthorphiledge
    • CommentTimeDec 16th 2020
     
    Posted By: borpinElectrical regs have got out of hand IMHO. The regs are an industry to force consumers to part with cash and line the pockets of the 'professionals'.


    Not sure that the regs introduce any unjustfied additional cost. Most of the cost of the items being discussed is scooped up by the manufacturers and next to nothing for the sparks doing the job, (the 'professionals'??).

    Id guess that a modern CU adds an extra few £10's to the cost of a job over a CU from a few decades back.
    • CommentAuthorborpin
    • CommentTimeDec 16th 2020
     
    Posted By: philedgeNot sure that the regs introduce any unjustfied additional cost.
    New socket in the bedroom Sir? That'll be £350. 1 x socket 1 x CU. kerching. AIUI *any* new work will require a new CU even if it is only a a couple of years old as it won't meet the *new* regs. Assuming you don't do it yourself of course.

    Soon they'll ban the sale of electrical supplies to anyone not approved.
    • CommentAuthorphiledge
    • CommentTimeDec 16th 2020
     
    Did the circuit that the new socket was added to already have RCD protection?

    AFAIK adding a socket to an existing circuit would only need a CU upgrade if the existing CU didn't adequately protect the circuit ie no RCD
    •  
      CommentAuthordjh
    • CommentTimeDec 16th 2020
     
    Even adding a new circuit doesn't need a new CU as long as there is an empty way in the existing CU, AFAIK.
  7.  
    If the existing CU has an RCD then it's fine AFAICT, and it will do if it's less than 15 years old.
    If it doesn't then you could add one in a separate box, or possibly use a socket with integral RCD, but it would be worth considering replacing the CU with a modern one for the reasons mentioned above.
    •  
      CommentAuthordjh
    • CommentTimeDec 16th 2020
     
    Posted By: WillInAberdeenIf the existing CU has an RCD then it's fine AFAICT, and it will do if it's less than 15 years old.

    Yes, sorry - forgot that part. I suppose an RCBO would be sufficient?
   
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