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Adding EV charge point to garage supply

Former Community Member
Former Community Member
Hi all, 

I need to replace the old fuse box in the garage with a CU and at the same time install a load balancing a fast charge outlet for electric vehicle.

Current installation has a sub panel in the house (40A) with type B MCBs: 20A for kitchen sockets and 32A for the garage supply. Main board is double RCD 80A, and DNO fuse is 100A.

10mm armoured cable underground to garage, approx 15m.

Plan is to move the kitchen sockets on to the main board (there is a spare), replace the adjacent garage sub panel for a 63A RCD panel with a 63A MCB, and replace the old fuse box in the garage with similar panel but with a 6A, a 16A and two 40A (one for the EV and one for the office that runs off this fuse box).


Does that work, or have I missed anything?


Thanks | Paul.
  • Your description of the current arrangement is very unclear. Describe it starting from the DNO cutout: what cables go from what to what? For each  CU/DB, describe where they get their feed from (e.g. from the main CU? Direct from the cutout via henley blocks? etc) and state what OCPD and/or RCD protects that cable.
  • Former Community Member
    0 Former Community Member
    Thanks for your time and apologies for being unclear. I’ll try again:
    1. DNO

    • 100A fuse

    • single rate meter (hopefully to be replaced with a smart meter ASAP)

    • Henley block

    • from Henley block to main CU (100A SVMS) with two RCDs: one 80A 30mA and one 63A 30mA. (Just double checked and not two 80A RCDs as I said in OP)

    • also from Henley block second feed to sub panel with 40A 30mA RCD and two MCBs one B20 for kitchen sockets which I could move to main board spare, and one B32 feeding 10mm SWA cable to garage.

    • garage has only wire-fuse box from which are taken a lighting circuit, a ring and a second SWA that goes the to office.


    I hope that that is clearer, but please let me know if there’s anything I’ve left out.

  • 40 A seems a lot for an office.


    Buried 10 mm² SWA will be good for 54 A so that 63 A MCB would be too high a rating for it.
  • Indoor or outdoor EV charging?
  • Former Community Member
    0 Former Community Member
    Thanks Chris, I’d misread the tables, but Method D looks like 60A, or am I missing something? Even so, with my existing SWA 10mm cable I’m restricted to 40A RCD protection?


    BTW: the office has underfloor heating and a hot tub next door ;)
  • Former Community Member
    0 Former Community Member
    Probably out door - Pod Point or EO mini smart.
  • Oh no, here we go again. He hasn't even mentioned the earthing, I hope posters haven't booked any holidays.


    Regard, UKPNZap
  • Former Community Member
    0 Former Community Member
    ? It’s ok UKPN, you can still have your (socially distant) holiday! I’m not planning the whole job (and not planning to do it myself either). I’m trying to work out the cost, and if I can use (some of) the infrastructure I already have, or whether I need to start laying new cables. I’ll come to the earthing later...


    ... but don’t let me stop you chipping in with earthing related advice ?
  • "I will come to the earthing later" It will be too late Paul, you need to think about it now!  


    Regards, UKPNZap
  • Another Topsy job, it just keeps on growing!