EV Charger and d.p mcb's

Discussion in 'Electricians' Talk' started by spaceman76, Jan 18, 2022.

  1. spaceman76

    spaceman76 Active Member

    Hi I do have a question im not 100% sure about. Ive completed my C&G EV charger course and as yet not installed one, but have a job come in so want to make sure im getting things right. The proposed charger has a built in OPEN device, as well as a built in A type d.p rcd. Im proposing to install a separate CU (via henley block) to house an mcb protecting the SWA feed to the charger; does this MCB need to be D.P ?

    Im thinking it does not as the charger has a built in D.P RCD, and for maintenance the supply's Line & N can be isolated via the CU's D.P main switch.

    Obviously if the feed out to charger was not of SWA then it would need its own RCD protection, but this is not the case here as its SWA.

  2. Comlec

    Comlec Screwfix Select

    I am sure someone with EV charger experience will come along soon to help.

    What concerns me is that after attending the course you are having to turn to an Internet forum for advice. I don’t blame you for asking but I would question the value of the course and the quality of the tuition and achievement of learning outcomes. hope it wasn’t to expensive.
    seneca likes this.
  3. spaceman76

    spaceman76 Active Member

    Thanks Comlec

    I just knew a comment such "why are you turning to a forum for advice, you should already know", would come up. But I just want to confirm my thoughts really; gotta admit I did forget to ask my tutor this while on the course. In my mind I dont see any reason to protect the cable with D.P MCb but maybe thought to ask . What I did omit from my original post was the need to fit a switch fuse for the SWA feed if run directly from henley's !
  4. Teki

    Teki Screwfix Select

    As the EV charger has the required protection devices built in, the SWA install from the CU to the charger should be treated in the same way as you would any other cable installation.

    Presumably, you've read the EV charger manufacturer's installation instructions?
  5. spaceman76

    spaceman76 Active Member

    Thanks for the reply yes the Charger has necessary PEN & d.p rcd built in. The supply of SWA I will treat as any other circuit with the necessary precautions. As I said in first post im almost certain if the SWA supply is protected by an MCB it dont need to be of the d.p variety, just wanted to double check for piece of mind.

    I expect the charger instructions wont be of much help regarding the supply requirements as each install would be different.
  6. MGW

    MGW Screwfix Select

    I do wonder about EV charging points, seems we have a number of problems.
    1) Overload.
    2) RCD being correct type.
    3) Protection against loss of PEN.
    But there is nothing to stop the install of a 32 amp socket upload_2022-1-20_12-7-20.png and a 7 kW type 2 plug in charger upload_2022-1-20_12-8-54.png and although some safety features built into the charger, it varies how much is built in, so possibly no protections against loss of PEN.

    There is also of course the granny charger.

    The idea of training installers to design the system seems good, looking out for looped supplies and informing the DNO, and ensuring no type AC RCD is used in the supply, and using current transformers to reduce charge rate when home lacking spare capacity. Plus what to do with a PME or TN-C-S supply, safe distance between earth types etc.

    But why bother when a plug in type 2 charger can be used? How long before we see the first court case because some one is injured?
  7. CeSparky1

    CeSparky1 Active Member

    The regs requiring pen fault etc say any car charger or socket likely to be used for car charging.. So the same rules would apply to a granny charger or other socket.
    spaceman76 likes this.
  8. spaceman76

    spaceman76 Active Member

    Easier said than done, how is the installer to know if the supply he's working on is at the far end of a looped supply without looking at next door(s). Dont know is likely the honest answer installers can put on the form.
    People do tend to like the idea of using their phones to see whats going on with the charger/charge rate ect, so most will likely go for the charger on the wall set up over a plug in commando socket or granny charger (not that im condoning their use. in fact I would prefer a socket and lead approach), however with with all these emerging variable tariff's from suppliers it will likely end up cheaper for the consumer to have a dedicated wall charger with all the whistles and bells (ct clamps, wifi enabled ect) so the chargers automatically draw the cheapest rate. One thing to be aware of when connecting an EV charge point to wifi is the potential for your wifi to be hacked; probably best to have a dedicated car charger wifi rather than utilising your home/office one, or dont use wifi atall and use the free cellular network if the charger has the facility.
  9. MGW

    MGW Screwfix Select

    Oh that opens a can of worms, like the socket likely to be used outside with old RCD regulations.

    If the owner says I have welding set I want a socket to plug it into, does the electrician say no you could plug a car charger into that socket.
  10. Dnsmith

    Dnsmith Member

    To go back to the original question the requirements are a combination of the iee regs and the manufactorers instructions.
    Under the iee regs the rcd protection (mcb) at the consumer unit does not need to be DP if it has this in the charger unit providing this is what the manufactorers instructions state.
    I have seen some where the manufactorers state double pole.
    If you do not comply with both if something happens it makes it more difficult to legally fight your corner.

    With adding outdoor sockets quotes and completion paperwork should state not to be used for car charging to cover yourself and a label adjacent would be a good idea.
  11. Dnsmith

    Dnsmith Member

    I went on the C&g ev charger course last november.
    A survey had beed carried out of installations (my cps bodies) and they said that 60% were dangerous or potentially dangerous (c1 or c2).
    The use of segrigated earthing on TT system is no longer viable as you need to guarantee seperation of the earthing system from the tncs (pme) system and there are not many circumstances when you can do this.

    Even when buying a dedicated ev charger unit you have to be very careful of the protection it has
    1) open pen fault protection-otherwise you will need to add this seperately such as a mat-e
    2) type a double pole rcd with 6ma dc detection or type b dp rcd.

    There are quite a lot of units for sale with no PEN fault protection.

    Interestingly the same risks exist for charging caravan or motor homes from an outdoor socket.
  12. sparko69

    sparko69 Screwfix Select

    In your situation you would be best to ask your scheme provider to clarify the position and then you have got the information first hand. Personally I would send an email so you have got it in writing. You pay them for support so when you need support just ask.
  13. MGW

    MGW Screwfix Select

    Seem to remember 2.7 meters from the building for caravan or motor home to comply with fire regulations.

    Clearly a caravan or motor home can be inside a show room, so must be a little more than simple 2.7 meters, but if the TT earthed parts are at least 2.7 meters from the building, then not really much of a problem.

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