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Assistance in choosing Main Consumer Unit

Discussion in 'Electrics UK' started by RetroKeys, 27 Jan 2021.

  1. RetroKeys

    RetroKeys

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    Hey guys n gals,

    I am looking to buy (it will be fitted by a professional to comply with new regs) a consumer unit as I get a good rate at some of the suppliers I use.

    I have a 3 bed house, and at the moment it only has the older style consumer unit with isolators (they dont look like the newer style ones) and there are only four of them; 2x 5amp, 1x 30amp and 1x40 amp.

    Its situated outside in the shielded box with the meter, and I need it updating as its just too old.

    For normal use, would I be right in suggesting a 6+6 split load consumer unit would be okay and give us the flexibility should we extend in the future?

    Im loathed to get an electrician out JUST to confirm my suspicions on the type of MCU to buy.

    Thanks in advance.
     
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  3. davelx

    davelx

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    These days all rcbo is the way to go. prices are much more reasonable than they used to be.
     
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  4. Taylortwocities

    Taylortwocities

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    a “split load” consumer is not the best plan. Cheaper, but not the best plan.

    Really, let your electrician design and install the right one.
     
  5. flameport

    flameport

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    No. Cheap, non compliant junk.

    That's the only sensible option.
    Impossible to determine what's required otherwise.

    Buying a consumer unit yourself and then expecting someone to install it will end badly.
    The installation will require a full inspection and test before any decision is made on which consumer unit is appropriate.
     
  6. Taylortwocities

    Taylortwocities

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    Agreed. It’s a bit like going to B&Q and buying a gas boiler, then phoning up a GasSafe plumber and asking him/her to come and install it.
     
  7. ericmark

    ericmark

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    We should before fitting a new consumer unit measure the earth leakage, we are told for multi circuits on one 30 mA RCD that 9 mA is the limit, never measured myself as my clamp-on meter only measures down to 100 mA, we should also test the insulation resistance using 500 volt, neutral earth faults can really cause problems, then we look at the equipment being used and select the type of RCD required, plus inquiry asking owner what he is likely to do in the future.

    It is possible a split consumer unit will do, with 16 circuits an all RCBO can work out expensive, and it may need a type B for electric car charging so since hard to get single module width RCBO type B some times one has to select rather carefully, but I priced up all RCBO v twin RCD for a 6 way and looking at £35 for the cheapest make, some of the more expensive makes it can get quite high, but the more expensive are only required when you want some thing special like double pole switching.

    Yes some electricians just bang in a consumer unit without investigating first, and when fitting all RCBO unlikely to be a problem, but with twin RCD's as I found to my cost when I fitted them in around 1992 you can go years not problem then it can trip out 3 times a week for a month then do another year with no problem, and I never did find a fault.

    Coming home finding it tripped, and resetting then looking at freezer door to see if had warmed to -4°C and you then need to debate do I bin all that food or not? At +4°C it is eat it now or bin, but is the reading good for whole freezer? That is of course if you have a freezer that displays the warmest temperature after a power cut. Clearly you don't want to open the door.

    Water ingress is another problem, my roof leaked and the lights in my flat under the house tripped the RCBO, this did not really matter, it could stay off until roof repaired, however with many circuits on the same RCD it would have needed that circuit disconnecting, calling out an electrician.

    So it does not take much for the twin RCD unit to work out more expensive to the all RCBO type.
     
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  9. SUNRAY

    SUNRAY

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    Your choice of electrician will usually happen after getting in 2 or 3 [or even more] electricians in to survey and estimate or quote for the job. That is the time and place to be asking for the information you are asking here. your selection of electricians at that point will either supply the list of parts they recommend/are prepared to fit or opt out of quoting.
    Some refuse point blank to install particulear makes or ranges within a make and usually curse to high hell if they have to make alterations in an existing unit they don't like.
     
  10. EFLImpudence

    EFLImpudence

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    If you have a 4 way CU (2 x lights, sockets and cooker or shower?) in the outside meter cabinet, then there will be a lot more work involved than just swapping it for a 12 way CU.
     
  11. John Peterhead

    John Peterhead

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    So looking at that, you have a 3 bed house with one ring main and I am assuming a shower. You cook by gas?

    Sorry mate but it sounds like you actually need a rewire or the sockets rectified pronto.

    I would say a DB is the very least of your problems.
     
  12. Captain Nemesis

    Captain Nemesis

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    doesnt sound like it would have been anywhere warm enough for long enough for things to go off. Unless you had stuff that was already off when you first froze it you would have been fine to just turn it back on and leave it.
     
  13. John Peterhead

    John Peterhead

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    Some electricians might do that but they should still test the installation upon completion? An earth leakage fault is near impossible to find sometimes. Thats the problem with RCD's RCBO's etc..

    I latterly worked on commercial washers and dryers (amongst other larger machines in the catering idustry) and earth faults are common where the cables rub against the side and eventually result in bare copper striking the side, virtually impossible to trace :(

    Freezer tripped ..... if it is still -4 it is still perfectly fine inside as the contents can last for a good couple of days if they are within the freezer compartment and its not opened ;) If its got to -4 though, that must have been left for a good few days but still frozen ;)

    Water ingress, refer back to the RCBO trip, another constant cause :)
     
  14. ericmark

    ericmark

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    Freezer off time and still OK depends on type of freezer and where in the cycle the power failed. A chest freezer likely a couple of days, but an upright freezer frost free depends on if centre of freezing cycle so likely 8 hours, or just finished de-frost cycle then looking at less than 2 hours.

    You also need to realise it has failed, my lights were on a different RCD to half the kitchen sockets, yes there is a light on when powered up, but you notice a light coming on, but not so much lack of a light.

    So normal working day 8 hours, plus travel time often looking at 10 hours, so the freezer needs to be OK for 10 hours.

    I saw my upright freezer fail, so I went into garage and switched on spare one, normally used for beer brewing, left it an hour for it to go down in temperature, and when I moved the food the food at top had defrosted. It was less than 2 hours total since it failed, I had it on an energy meter so knew exactly when it failed, plus I was there when it happened.

    We also lost two freezers full when we went to live with mother, we were away for over a week, so no question all went in the bin. I don't know how much the food cost, but I would think far more than the extra it would cost for all RCBO, yes they can still trip, but far less likely, only tip had in this house was correct had water ingress, but last house very rare to find out what caused the trip, basic fact 30 mA x 2 = 60 mA and 30 mA x 16 = 480 mA so the CU with just 2 is much closer to the edge to CU with 16.
     
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