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Car charger install, existing consumer unit?

Discussion in 'Electrics UK' started by cjp2k, 8 Jun 2020.

  1. cjp2k

    cjp2k

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    Hello everyone, I need some advice

    I have ordered a plug in hybrid BMW and need a home charge point. The BMW garage have passed me onto a third party who will install as part of a grant, however I have been told they must install a secondary consumer unit at my cost?

    My current consumer unit is a 16th edition crabtree with most circuits on the RCD side.

    Only exceptions are the downstairs lights on the un protected side but on a rcbo and the smoke and doorbell circuits on standard mcb.

    I have one spare way in the board on the non RCD protected side, surely they can just use that with a suitably sized RCBO?

    Thanks
     
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  3. oldbutnotdead

    oldbutnotdead

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    Not according to their scheme rules apparently (which sound like a bit of a scam - you get to pay 100% of their price for a garage CU & 25% of the price of the charging point).
    You need to do some homework.
    First check your car is eligible for a grant (being a hybrid it may not be).
    Second get prices from them both for this secondary CU and for the actual charging point.
    Then go online and get some comparison prices
     
  4. cjp2k

    cjp2k

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    Thanks for that i will look into it when I get to work and check the paperwork

    The consumer unit is in the integral garage and the charge point will be about 1m away on the front wall of the house, if their costs are more I will just go fully private.

    Is there any reason technically not to put the charger unit connection in the main consumer unit? We are thinking of converting the garage at somepoint so the consumer unit will be part of the house at somepoint
     
  5. oldbutnotdead

    oldbutnotdead

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    Probably not- you're almost certainly going to get a 7kwh charger which requires 32A. Unless you've got a lot of high current items already installed (electric showers) then existing setup should have enough capacity.
    From the installers POV, requiring a sub CU ( Henley blocks etc) makes their life much easier- no need to survey, no need to acquire correct brand of MCB/RCBO- but they may not be passing that saving on to you so beware.

    EDIT As far as i know, you can apply for the grant as an individual BUT you may have signed that option away as part of the car deal. Check that you haven't already ordered the work from this 3rd party supplier, if you have then pause it til they supply price information.
     
  6. ericmark

    ericmark

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    I watch a video of some one fitting a Ziggy car charging point, it seems from the video that the unit monitors how much power the house is using so it can ensure the car charger does not exceed the supply available to the house, and it could charge at over 45 amp which is the maximum size MCB that will fit in any consumer unit, so it was not supplied from the consumer unit, but direct from mains incomer.

    It was only passing interest to me, so did not note details that much, but it seems there are different makes of charge units and it all depends on the make as to what is required, I know the milkman across the road to me the charge point is on wall outside garage and uses the TN-C-S supply from a MCB in main consumer unit, I looked at it and thought how can a car be charged direct from a TN-C-S supply? However watching that video it does seem there are methods that can be used, but I have the feeling it was not used in his case. It was some years ago it was all fitted so maybe rules have changed.

    I assume this is why people need to go on special courses to fit the units. As a normal electrician I could not fit one.
     
  7. flameport

    flameport

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    Yes, entirely possible.
    Compelling people to pay for a separate CU no matter what sounds like a money making exercise for the installer company. Find someone else.

    To be eligible for the £350 grant, it must be a charger that's on the government list, and it must be installed by someone approved on the OLEV scheme, and there are other criteria relating to the vehicle.
     
  8. flameport

    flameport

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    Yes, entirely possible.
    Compelling people to pay for a separate CU no matter what sounds like a money making exercise for the installer company. Find someone else.

    To be eligible for the £350 grant, it must be a charger that's on the government list, and it must be installed by someone approved on the OLEV scheme, and there are other criteria relating to the vehicle.
     
  9. Risteard

    Risteard

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    The RCD must break all live conductors which may make an RCBO impracticable for that DB. It will also need to be Type A at a minimum. (Sometimes a Type B RCD may be required.)

    Requiring a separate DB is far from improbable.
     
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  11. alan333

    alan333

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    I'm not a sparky but had a car charging point installed under a grant system in Scotland a few years ago (free). As I understand it, the main consumer unit can only handle a certain amount of current. For example I believe that we shouldn't install a second electric shower in our houses since if they were both in use along with a large draw from the oven/microwave/kettle etc then it could overload the CU. I expressed these concerns to the installer, who said no problem and fitted a second small CU beside the main one, just for the charger. I reckon he was originally just going to use a spare way on the existing board, since that's what was done in our neighbour's house by the same installing company.
     
  12. flameport

    flameport

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    That is true, but unless it's decades old, consumer units are generally rated to 100A, which is the usual maximum for a single phase supply.
    Adding a second consumer unit doesn't provide any extra supply capacity.
     
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  13. alan333

    alan333

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    I didn't realise that. I thought it was the power going through the CU which was 'capped'. So I might as well have let the guy use the spare way on my CU for adding the car charger? (My CU is rated at 100A, as you guessed [Crabtree Starbreaker]).
     
  14. davelx

    davelx

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    Most of the home charging point I have looked at have a DP type A or B RCD built in - so an RCD may not be needed in the CU at all, depending on other factors.
     
  15. ajohn

    ajohn

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    You'd need to check this carefully but some of the chargers use some form of rcd that breaks all 3 connections and swa is used to run to them. That then needs an mcb or fuse to feed it. As swa is used it doesn't need rcd protection. On that basis fitting a switched fuse unit makes more sense or an unbelievably small cu when one is needed.

    So called high integrity CU's make sense with this sort of arrangement as they have 2 ways without rcd protection.
     
  16. Risteard

    Risteard

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    EO Mini units I have fitted do not come with any RCD protection internal to the EVSE.
     
  17. ajohn

    ajohn

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    Only thing I can add is that at least one brand of charger gets round what can be an earthing nightmare. Trips usually disconnect L and N. The type that gets around the earthing problem breaks the earth connection as well. It's to protect battery current running to mains ground.
     
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