Shed electrics

Discussion in 'Electricians' Talk' started by kebab_kebab, Jun 29, 2022.

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  1. kebab_kebab

    kebab_kebab New Member

    I am looking to add electrics to a new shed which is against the wall of our utility.

    The Shed will need to run a few LED lights, a chest freezer and charging points for power tools. There is unlikely to be any heavy load, I think the only 'mains' tool I use is a leaf blower.
    The closest socket is a spur from the downstairs ring.

    Am I right in saying that I can spur the whole shed off this socket if I do it via a 20A DP FCU? The light will be off a second FCU (3/5A).

    The Main Consumer unit was installed 10 months ago, so is fully RCD protected but do I need a separate level of RCD protection for the shed?
     
  2. jonathanc

    jonathanc Guest

    In answer to your questions : no and no
     
  3. kebab_kebab

    kebab_kebab New Member

    Thanks for the reply, could you elaborate on the first no?

    Do I need some other form of protection to spur from an existing spur, or is it not allowed at all?
     
  4. chesterw

    chesterw Well-Known Member

    When you say spur do you mean a fused spur via a fcu and 2.5mm cable? If it is you can add to it but you will be limited by the fuse in the spur - max size 13A.

    If its an unfused spur you cannot add to it.

    And there's no such thing as a "20A DP FCU" - max size is 13A
     
  5. kebab_kebab

    kebab_kebab New Member

    My mistake, I think the piece I had read talked about isolating the shed with a dp switch rated at 20A, but unfused.

    I currently have an unfused double socket spur. If I replace this with a 13A FCU, Add a socket next to it for the utility and then run my shed electrics from that I should be OK?

    Just need to check load as this will add a washing machine and tumble dryer.
    :(
     
  6. kebab_kebab

    kebab_kebab New Member

    I think the socket powering the washing machine and tumble dryer is probably already over capacity with them both running, so will need to solve that problem.

    i have identified the boiler in the utility is on a 3A FCU spurred from the ring.
    Can this be replaced with a 13A unit To feed the Shed and a new 3a FCU for the boiler?

    it would look like this....

    RING

    13A FCU - 3A FCU - BOILER

    ├ Double Socket (~100w chest freezer)
    ├ Double Socket (charging point for drill & hedge cutter)

    └ - 3A FCU - Internal Light (40w Strip Light)

    └ - External Light (10w Bulb)
     
  7. Tony Goddard

    Tony Goddard Screwfix Select

    Provided the first 13A spur is on the ring or the only spur (ie not spurred from a spur) and everything (including the boiler spur) is fed from its load terminals then what you suggest will work.

    The circuit must have 30mA RCD protection at source (this is very important) and take into consideration ingress of water/dampness/possible rodent damage where applicable.
     
  8. BGL

    BGL Member

    I suggest that you get an electrician to test & advise as you may be adding to a problem you are connecting to. There are resistive limits to extending circuits.
     
  9. chesterw

    chesterw Well-Known Member

    Add a double pole 20A switch between the "RING" and "13A FCU", so that if there's a fault that trips the cu rcd, the whole lot can be isolated, to get the house back to normal.
     
    kebab_kebab and jimbobby like this.

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