Bathroom Extractor Fan Wiring

Discussion in 'Electrics UK' started by LaurenceGregory, 27 Aug 2003.

This topic originated from the How to page called Installing wiring for an extractor fan.

  1. LaurenceGregory

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    1. Where can I take a feed from to supply the Double Pole FCU, must this be from the 13A ring main or can it be from the Lighting circuit?

    2. From the Double Pole FCU (located outside the bathroom) must there also be a Double Pole ceiling mounted switch as well in the circuit?

    3. Could you supply a typical wiring and/or circuit diagram to show this?

    Regards,

    Laurence Gregory
     
  2. breezer

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    if you use a fused spur you can take it from the lighting circuit, also if you leave out the switch you then wire it across the bathroom light supply, so anyone using the bathroom turns on the lights and the fan starts
     
  3. LaurenceGregory

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    Thanks for that Breezer, the only thing is, I don't want the fan to come on when the light does. I would like the option to just have the light on without the fan. So in this case how would I wire it up? (PS there is a window in the bathroom so the "not to have the fan come on with the light option" complies with Regs .

    Laurence Gregory
     
  4. breezer

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    similar as previously mentioned but you should install a pull cord switch in the live to the fan, also you should feed it from the live, not switched live
     
  5. PatM

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    [Arising from 27 August post]

    Hi Breezer (or others) - I've looked through this site and others for info on wiring a timer fan on the lighting ring but controlled by a separate pullcord not by the light switch. Before you ask, the instructions with it don't show wiring of a timer fan for non-light-switch control. I am a bit confused by your reply about wiring in a pull cord in the live to the fan.

    I can't work how how it would go there - but I must have misundertood what you meant.

    The way I understand the circuit should work is:
    1 Lighting ring live to pull cord to
    2 Pull cord switched live (black/red) to junction box terminal (Switched live) to
    3 Switched live (yellow in 3core+earth) to
    4 3pole isolator switch to
    5 Timer fan

    The 3pole isolator switch would also get live and neutral (blue) feeds from the lighting ring

    I had laid this out as ASCII art but that won't work here :(


    Thanks for any comments/warnings/advice

    Pat
     
  6. breezer

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    colour choice is yours, but all you need to do is take feed from light (permanent live neutral and earth) take it via 3 pole switch to fan, then from fan to second pull cord (2nd pull cord operates fan)
     
  7. securespark

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    Forgive me for being thick, breezer, but why do you need a triple pole isolator if you only have L+N coming in a DP will do, surely?

    And in case anyone reading this is interested, you can get pull cord triple pole isolators for fans so you can put iso in bathroom. Ashley make them.
     
  8. breezer

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    in case it is a timed fan.

    so that the live , switched live (timed fan) and neutral are isolated
     
  9. securespark

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    Breezer

    Surely that means a live feed to in terminals of triple pole fan,

    live and neutral feed from out terminals to fan. tap off somewhere for live to operating switch, taking the operating switch output to the incoming switched live terminal of triple pole isolator. THen the switched live out terminal on isolator goes to fan.

    Or am I seriously up the creek?
     
  10. breezer

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    sorry i read but do not quite understand.

    what i am saying is you must be able to completely isolate the fan, so in effect you take a 3 core t & e fom the light (L, N & switched live) to the triple pole isolator then to the fan
     
  11. securespark

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    Breezer he wants the light to come on without fan, so you could wire a sep pullcord just to trigger fan.

    OR Just switch off the triple pole iso when want light on its own.
     
  12. breezer

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    R, I C
     
  13. billyrae

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    Hi folks,

    Sorry if I'm being thick but from a safety perspective what is the purpose of the triple pole isolator. How does this help if it's always switched on as would normally be the case?

    I am in the process of installing a fan connected to a 6amp lightiung circuit.

    cheers for any help.
     
  14. dingbat

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    Firstly, you picked an old thread for this topic - how far back did you read? :D

    But to answer your question, if you have a fan with a timer it requires a permanent live, a switched live and a neutral (as well as an earth of course). The three-pole isolator is so that you can safely isolate the supply to the fan without having to isolate the lighting circuit you've connected to.
     
  15. billyrae

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    Thanks for the quick reply. So am I right in saying that the isolator is for convenience rather than a safety requirement as I can always switch off the entire lighting circuit at the consumer unit to work on the fan?
     

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