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Electric upgrade design advice/help

Discussion in 'Electrics UK' started by egtrev, 26 Mar 2021.

  1. egtrev

    egtrev

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    Hello,

    Sorry this is quite along post.

    I purchased and moved into a 3 bed bungalow last year, the electrics are original from the late 80's except the kitchen has had sockets changed to doubles at some point, a shower has been added about 5 years ago and the consumer unit has been updated about 12 years ago (has one RCCB covering all MCBs except all the lighting circuits)

    The main issue is there are a lack of sockets throughout the whole bungalow (about 120sqm) and there is just one ring final circuit covering the whole bungalow, at the moment we have to be careful using the Kitchen equipment (washer/dish washer/dryer/fridge/toaster/kettle/microwave) as it will trip the MCB if too many are running. I do have a UPS in a couple of the rooms as I have extensive computers/servers/tech that stay on most of the time but still a pain when it trips.

    I'm at the point now where I want to change the consumer unit, reconfigure the circuits and add some extra sockets along the way. I have only the basic understandings so my electrician will be carrying out the works and I will be doing all the chasing and getting the floorboards up and removing redundant cables where required.
    We're just settling now on the design and I want to check if I'm going in the correct direction (after speaking to a few electricians they all seem to have different preferences)

    Here's is the current discussed plan/details:

    Lighting:
    Currently 1.5mm2 cables feeding 3 separate circuits, 2 split the internal ceiling lights and the 3rd is outside lights.
    Happy with the lights and these will be left as is for now and just put on individual RCBO's, the alarm will be cabled to a new separate RCBO instead.

    Central heating:
    Currently on it's own MCB, will keep the same just changing to a RCBO.

    Shower:
    Currently 6mm2 cable for 8.5kW shower on 40A MCB.
    Will just be moving it to a RCBO.

    Bedroom 1 and 2:
    Currently the first sockets (2 in each room) off one leg (A) of the ring final circuit (2.5mm2)
    Plan is to break the ring at the end of bedroom 2 before Bedroom 3 and put these 2 rooms on their own radial 20A RCBO, then add a few sockets in the radial where required.

    Living room/Dining room:
    Currently the first sockets (2 in each room) off one leg (B) of the ring final circuit (2.5mm2)
    Plan is to break the ring at the end of Dining room before the kitchen and put these 2 rooms on their own radial 20A RCBO, then add a few sockets in the radial where required.

    Bedroom 3 (Office/data room):
    Currently in the ring final circuit 2.5mm2 after the other 2 bedrooms before the kitchen.
    This will be broken once the other bedrooms are put on their own radial, plan is to remove the cable from bedroom 2 and to run a new 2.5mm2 cable from the consumer unit to the first socket, remove it's cable linking it to the kitchen and putting this room on it's own 20A RCBO and adding a few sockets in the radial where needed.
    I want this room separate as has lots of equipment I want to keep on whenever possible (not really high load equipment maybe 3000W total)

    Kitchen:
    Currently 5 sockets in the middle of the ring final circuit 2.5mm2
    This will be broken when the other radial circuits are created, plan is to remove the cable from bedroom 3 and Dining room and to run 2 new 2.5mm2 cables each side of the kitchen to make this back to a ring final circuit on it's own 32A RCBO.
    Optional thoughts for the kitchen.
    1. Currently have a gas cooker plugged into one of the kitchen ring sockets (just for the ignitor/display). I was thinking while chasing maybe having a new 10mm2 cable put in from the consumer unit on a new RCBO for a proper cooker socket for potential future use (incase we have a high power electric oven in the future)
    2. I mentioned earlier my kitchen equipment, when I've added the amps up it seems potentially could be pushing it, so I was thinking about having a 4mm2 cable put in and creating a separate radial on a 32A RCBO with 2 sockets just dedicated for the washer and dryer. I don't know if this just overkill/unnecessary?

    Any advice/input is appreciated, the above is all the basic overall design I'm looking to go with but happy for suggestions or anything that's been overlooked.
     
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  3. Aragorn84

    Aragorn84

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    3000w is a lot of IT kit.... The rack full of kit in the office is pulling <1500w

    Mining farm? :LOL:
     
  4. oldbutnotdead

    oldbutnotdead

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    Not read your design thing cos there's wayyyy to much detail in there.
    All you need to tell your electrician is where you want sockets, fcus, light switches, light fittings, cooker outlets, shower supplies etc etc. You can also add preferences (eg you'd want the kitchen on its own rfc, you want a radial with dedicated rcbo for your it room, you want to use this design of socket/switchplate/whatever.
    Your electrician will then design the circuits, chases, cable sizes and routes to give a safe installation.
    Quite likely they'll be happy for you to do wall and backbox chases but it is at their direction to their specification.
     
  5. JohnW2

    JohnW2

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    I suspect that he's probably adding up the 'maximum capabilities' of the PSUs in each of the items (e.g. 300W - ~1,000W for ATX PSUs) - which is likely to end up with a very much higher figure than the true in-service consumption.

    Kind Regards, John
     
  6. Aragorn84

    Aragorn84

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    Wishful thinking. Unfortunately most trades i've dealt with do things the cheapest and easiest way possible to maximise their profit, and you end up with a **** result.

    OP is going about things the right way, ensuring a solid spec sorted out up front. Also means if hes getting quotes, hes getting prices for comparable work. Really grinds my gears when domestic trades take umbridge with clients wanting to properly specify work. In commercial situations, even housebuilding, the trades would be given an exact spec by the client and would install to that spec, not whatever they fancy doing themselves.

    Overall plan looks fine to me, personally i'd run two "cooker" supplies, one for a hob, and one for the ovens. Might not need the hob supply if your on Gas, but might be handy to at least run the cable in now if it will be difficult in future and you want to fit induction hob instead for instance.
     
  7. ericmark

    ericmark

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    In the main it seems you have a good plan, and with all RCBO's unlikely to have problems, however be aware there are two types of RCBO's and there are also SPD and the prices manufacturer to manufacturer can vary hugely.

    The SPD can range from £25 to £125 and the RCBO can vary £13 to £35 also there are some which switch both line and neutral (although only line monitored for over load) but most switch only line, also there is type AC and type A with cheap range £12.12 for type AC and £18.60 for type A.

    I made a mistake, I did not realise I had been supplied type AC so three times the cost to upgrade now to type A to what type A would have cost extra in first place.

    If you have a TT supply you may have little selection in type and make of components, as the cheaper makes don't seem to do double pole versions, so you may be forced to use the more expensive makes. With computers, don't want to call it IT as that is a method of earthing, you will have likely many switch mode power supplies so really should be looking at type A, as to if lights can use type AC I would say yes, as most lights fed by a current limiting capacitor so very little chance of any DC.

    In the main electricians are trying to work to a price, and clearly using type AC with some makes is cheaper, although with more expensive makes the difference is less. We have debated on this forum about the SPD, with many considering them as snake oil, but with expensive equipment I would consider it to be prudent to air on safe side, and not a clue why, but the price varies a lot between makes.
     
  8. oldbutnotdead

    oldbutnotdead

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    Fair comment regarding routes and outlet specifications (though you'd like to think in a commercial setting whoever prepares the spec will be clued up enough to not specify unworkable stuff- running cables through steel lintels is a favourite trap. Also fair enough the client specifying a requirement for a 50A cooker outlet and deliberately specifying that the cabling must be capable of carrying that load (to prevent bodgers chucking a bit of 2.5 in knowing they'll be long gone by the time their bodge is discovered).
    Not fair enough specifying cable sizes (except as a minimum caveated by length, any thermal insulation or unusual installation methods).
     
  9. egtrev

    egtrev

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    :LOL: Not mining a farm, just running lots of hosted VoIP clusters/servers (among other things). They're pulling between 2500/2800w total on average when checking and adding up my various rack UPS load readings, so maybe not quite 3000w.

    As far as the electrics - Telling the electrician to decide/design everything is not what I'm looking for, hence trying to put as much detail as I can for help here, I've come across lots of tradesman that just go with whatever gets the job done quickest/most profit, I want to have some knowledge so I can assure and have peace of mind that it is getting done right, I don't want to be left later thinking wish I'd have had this/that

    @ericmark thanks for the info, I'll be supplying pretty much everything myself (except the cable/small parts), so I'll keep that in mind. Wylex/Hager are the 2 brands I've been looking at, but haven't settled on anything yet.

    @Aragorn84 the kitchen is getting tiled so it is really the one I want to get right if I can, makes sense to have one for the hob and oven, thanks.
     
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  11. egtrev

    egtrev

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    @oldbutnotdead nothing really helpful so far. Sorry I've put too many details for you to read, I just wanted to put as much down as I can so everyone can get a good visual on the current and new potential setup.
    If you do have any input/suggestions/concerns on what I've stated as the design/plan as others have that would be appreciated, if not, might be best moving on to a different shorter less detailed thread and help out there.
     
  12. EFLImpudence

    EFLImpudence

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    For a start -

    Some flats have 10mm² as their supply cable - for everything.

    You will not require it just for a cooker.
     
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  13. egtrev

    egtrev

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    Thank you, noted. What do you think of other things? Any help is appreciated.
     
  14. EFLImpudence

    EFLImpudence

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    1mm² is more than adequate.

    Ok.

    Ok. You could go up to 10.5kW and 45A (installation method permitting).

    Ok? Breaking the ring will leave two 20/25A radials. is that what you meant?
    Not much point breaking the ring really; you can add as many sockets as you want.

    Ok - as bedrooms

    Ok. Hard to picture not knowing the layout.

    Ok.

    As above.
    32A / 4mm² (although everyone still uses 6mm²) is good for 19kW of cooking appliances.

    Sounds like overkill.
    You could have two 4mm² / 32A radials sharing the sockets.

    It's not really design - just what you think you need.

    A separate circuit for the kitchen is likely all that would be beneficial (not counting your equipment but 3000W is only 12.5A)
     
  15. EFLImpudence

    EFLImpudence

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    How is the bungalow wired at the moment?

    Sometimes they have the ring in the loft and all the sockets on spurs.
     
  16. egtrev

    egtrev

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    At the moment it's one ring (CU > Bed 1 > Bed 2 > Bed 3 > Kitchen > Dining > Lounge > CU) all wired under floors except kitchen which is a concrete floor so they have gone up the loft then returned back down.
    Lights are run in the loft through ceiling roses.

    My thinking was the ring would be broken and cables removed where as marked with [X] so (CU > Bed 1 > Bed 2 [X] Bed 3 [X] Kitchen [X] Dining < Lounge < CU)
    It would make then Bed 1/Bed 2 radial and Dining/Lounge Radial (once each leg moved to own RCBO) and leave tBed 3/Kitchen not working.
    New cable 2.5mm² run from consumer unit to Bed 3 to make it a radial.
    New cable 2.5mm² run from consumer unit to either side of the kitchen to make its own ring again - or could run 4mm² as you suggested and split to 2 radials.

    This is true as the others aren't a big load requirement.
    My thinking with moving the lounge/dining and bed 1/2 to separate radials was more the convenience of being able to isolate them if needed and that because they are the start of either side of the consumer unit on the current ring they could easily drop into separate radials without further cabling, if that makes sense.

    Appreciate all the help and input :)
     
    Last edited: 26 Mar 2021
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