mystery switch with fuse and light in my cupboard

Discussion in 'Electricians' Talk' started by Kostas, Oct 11, 2019.

  1. Kostas

    Kostas New Member


    I've this switch in my cupboard and I don't have a clue what it does. Does anyone know? There isn't any obvious usage for it, there is no other plug in the cupboard or any device. There is no machine that can use it at the nearby bathroom or room.

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  2. Tony Goddard

    Tony Goddard Well-Known Member

    The fitting is a Fused Connection Unit (FCU) or old term a fused spur. this one is an FCU switched with neon to be correct. They are used to switch fixed apparatus such as (but not limited to) heaters, electric towel rails, immersion heaters, central heating boilers etc etc..

    Carefully undo the screws (with mains off at fuse box) and pull the plate forward, you will see terminals marked L In/Line, N In/Line, these will have wires in, then their will be terminals marked L Out/Load, N Out/Load, if these have wires something connects to it, if not then it is not feeding anything.

    Look at your consumer unit/fuse box, switch off the breakers one by one until the red light goes off - what is written on the label of that breaker?
  3. Kostas

    Kostas New Member

    Tried the switches of the breaker, it went off when i turned off the "bow ring". But so did my tv.
  4. Bazza

    Bazza Screwfix Select

    It’s on a ring final circuit then, but it may not even be in use. Have you done as Tony asked, are there any wires on the load terminals of the FCU?
    Turn that breaker off first do it’s not powered if you unscrew it.
  5. Tony Goddard

    Tony Goddard Well-Known Member

    Looking at that cupboard, was it ever an airing cupboard with a tank in it?
  6. peter palmer

    peter palmer Super Member

    It might not do anything, turn off power, unscrew the front and take a picture, could be for an optional extra like an alarm panel or towel radiator.
  7. Bogle Crag

    Bogle Crag Active Member

    Some properties built under NHBC specs had provision for heaters in cupboards back in the 80s

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