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Extractor fan question

Discussion in 'Electrics UK' started by funinacup, 16 May 2020.

  1. funinacup

    funinacup

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    So got an inline extractor fan in the loft. 3 pole isolator fed from a ceiling rose (line loop N + E). Orange light on isolator comes on and cables to fan are live, but fan doesn't run.

    All the JB's in the loft are in old metal conduit, and all black + red wires. The bathroom and a couple of cupboard lights have been fitted more recently so there is 1mm T+E to them and that's where I found the ceiling rose, but got a feeling something isn't quite right somewhere.

    I'm going to wire a flex to the fan and plug it in to make sure it's working but after that I guess it's got to be a wiring configuration issue with where its connected to at the ceiling rose?

    Thanks
    Michael
     
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  3. JohnD

    JohnD

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    How did you ascertain that?

    (If you say "neon screwdriver," hit it with a hammer and throw it in the bin.)
     
  4. funinacup

    funinacup

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    Voltage detector pen. Is that any better than the neon screwdriver?
     
  5. JohnD

    JohnD

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    save up. When you reach £12, buy a multimeter.

    use both prongs.

    Test across the N to the L, and the N to the SL.

    Then, test again under load.
     
  6. flameport

    flameport

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    No.

    You need something that actually measures the voltage using two probes such as a multimeter or voltage indicator.
     
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  7. funinacup

    funinacup

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    This is on the list of testing things today. I do have a multimeter
     
  8. JohnD

    JohnD

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    That should do the trick, then.
     
  9. funinacup

    funinacup

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    Will report back!
     
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  11. funinacup

    funinacup

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    So funnily enough I can't find a permanent live at the ceiling rose. There's only 240 if the light is switched on...

    Can I take a perm live from somewhere else in the loft?
     
  12. JohnD

    JohnD

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    show us a photo of the ceiling rose please, open, to show the wires.

    And inside the box where the light switch is.

    How old is your house?
     
  13. funinacup

    funinacup

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    Will do the photos shortly. House is 70s.

    Just for sanity, if I want the fan (timer version) controlled by its own pullcord and not at all influenced by the bathroom lights, do I have to run a T+E from a ceiling rose or JB in the lighting circuit to a triple pole fan isolator switch, and 3C+E from the isolator to a switch/pullcord operating the fan?

    Sorry if I'm getting it confused. Appreciate the guidance!
     
  14. JohnD

    JohnD

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    2&E to switch, then 3&E to isolator then fan.

    SL only exists at and after the switch.

    But I think switching by light switch is better. Some people have an aversion to ventilation and will not turn on the extractor until water is streaming down the walls.
     
  15. funinacup

    funinacup

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    Yeah I hear you. We have a massive bathroom window with so never need the lights when having a shower so prefer a separate switch.

    Pullcord for turning fan on and off would be best. What kind am I looking for? I keep seeing triple pole fan isolator ones, is that right for this application?

    If 2+E going to switch, and 3+E coming out, does that mean you must add a loop wire from L to SL on the supply side of the switch?

    Thanks so much for help so far.
     
  16. EFLImpudence

    EFLImpudence

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    There are several ways of routing the wiring depending on what you have at the moment.

    To add a separate switch for the fan, you need the cable from the switch connected to a Permanent Live and the existing Switched Live to the fan which has been disconnected from its present switched connection. Neutral remaining the same.

    It matters not where these connections are made - at light, isolator, fan or unnecessary junction box.
     
    Last edited: 17 May 2020
  17. funinacup

    funinacup

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    That makes sense, thank you.

    If I'm running 2C+E to the switch, then 3C+E from switch to isolator, should I take a loop wire from the live to the switched live in the switch, so that the output of the switch has both live and switched live?

    Thanks all!
     
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