Garage feed in new build

Discussion in 'Electricians' Talk' started by slickfonzy, Jun 22, 2020.

  1. slickfonzy

    slickfonzy New Member

    Hi there,

    I've recently moved into a new build with a detached garage. The garage already has a supply in SWA which terminates inside the garage in a 13A FCU, from which a double socket and lighting are run. The feed to the garage runs from a dedicated 16A MCB in the house CU and is RCD protected there too. Since it runs from the 16A MCB, why is there a need for the 13A FCU at the garage end?

    Thanks.
     
  2. rogerk101

    rogerk101 Screwfix Select

    No need for that at all. Feel free to remove it.
     
    slickfonzy likes this.
  3. Coloumb

    Coloumb Screwfix Select

    Probably the lighting ctt. is run in 1mm or 1.5mm.
     
    slickfonzy likes this.
  4. slickfonzy

    slickfonzy New Member

    Thanks for such a quick reply!
     
  5. Coloumb

    Coloumb Screwfix Select

    Roger has given you some very poor advice. He is not a spark. DO NOT REMOVE IT UNLESS YOU ARE 100% SURE IT IS SAFE TO DO SO!!! None of us here have any visibility of what your set up is like and it might well be there for a reason.
     
  6. sparko69

    sparko69 Screwfix Select

    The FCU is probably there to protect the cable from drawing more than 13 amps so leave it there until you can get it confirmed
     
  7. slickfonzy

    slickfonzy New Member

    Thanks all, the lighting is indeed in 1mm, mostly clipped direct but the vertical drops to and from switches are in surface mounted conduit.
     
  8. unphased

    unphased Screwfix Select

    13A fuse is unsuitable for 1.00mm2 T&E. You may find it's a 3A if you check. Is it the light switch? A few are wired like that.
     
  9. sinewave

    sinewave Screwfix Select

    Someone who 'knows' what they're doin needs a look first.

    A) We need to know what the SWA size is
    B) We need to know how the socket is wired?

    Could be looped in/out from the supply side of the FCU, which as stated could well have a 3A fuse in for the G-Lights and hence the socket is actually protected by the 16A MCB in the house.
    Doubt the socket is being fed from the outgoing side if indeed the FCU is at 3/5A

    We won't mention TT earthing lol! :D
     
  10. Coloumb

    Coloumb Screwfix Select

    ooooooooooooooooooooooooooooooooooooooooohhhh look who's back!!!!
     
  11. sinewave

    sinewave Screwfix Select

    :D

    Don't get excited mate!

    I'm just bored so thought I'd check in on you Chumps, make sure ya all playin nicely! :cool:
     
  12. Coloumb

    Coloumb Screwfix Select

    Ah shame! Still doing lecky stuff?
     
    sinewave likes this.
  13. sinewave

    sinewave Screwfix Select

    Nah, not if I can help it matey, Air Con diagnostics these days, drive a lot and maybe 60 mins work on-site. :D
     
  14. Coloumb

    Coloumb Screwfix Select

    Nice 1.
     
  15. slickfonzy

    slickfonzy New Member

    It's 2.5mm SWA into the FCU, then 2.5mm TE from the FCU to the garage socket and 1mm TE also from the FCU to the light. Definitely a 13A fuse in the FCU. The TE for both is in surface mounted conduit for the vertical runs to/from the FCU, socket and light switch, and directly clipped to the roof joist around the top.
     
  16. unphased

    unphased Screwfix Select

    In reality the 13A fuse won't be a problem for a lighting circuit especially one with so few light fittings as in a domestic garage. Good electricians would put a 3A or a 5A in it because it is correct to do so. 1.5mm2 cable however is perfecly fine on a 13A fuse. It might be 1.5mm2.
     
    slickfonzy likes this.
  17. slickfonzy

    slickfonzy New Member

    Thanks for that. In that case, would it be acceptable practice to move the 2.5mm2 T&E for the sockets to the "input" side of the FCU so it's directly connected with the SWA from the house, where it would still be protected by the 16A MCB and RCD in the house CU, then that would leave only the 1.0mm2 T&E for the lighting on the fused side of the FCU, so the fuse could be dropped down to a 3A or 5A?
     
  18. MGW

    MGW Screwfix Select

    That is likely what was intended in the first place, I would have used a switched FCU for the lights, but houses are wired in stages, first and second fix, so maybe was not the same guy who did both, not really a fault, so the guy doing the installation certificate would be unlikely to raise it as a fault. In the main we stick to two BS1362 fuse sizes, 3 amp and 13 amp, and 3 amp is ample for lights.
     
    slickfonzy likes this.

Share This Page