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Bathroom Extractor Wiring

Discussion in 'Electrics UK' started by Glyn1959, 21 Mar 2020.

  1. Glyn1959

    Glyn1959

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    Hi I had a sparky wire an extractor in a new bathroom with an isolator switch outside on the landing. I couldn’t understand why sometimes it worked and sometimes it didn’t!
    I removed the fan returned it to Toolstation and fitted a replacement and still the same.
    I checked the wiring in the switch and the permanent live was wired to L1 and the switch live to L2 whereas YouTube videos showed the opposite. I changed them around but no difference.
    I turned the bathroom light on and had a lightbulb moment literally.
    I was under the impression that the isolator switch alone drive the fan and not the light pull cord too - how embarrassing
    All is working now however which wiring is correct? Permanent to L1 or L2?
    Thanks for your patience.
     
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  3. jj4091

    jj4091

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    Should be a triple pole switch so either way round is ok.
     
  4. muffking

    muffking

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    Is it a timer fan. i.e. is it supposed to run for a while after you turn the light off?
    If so, then an L1-L2 reverse will stop the timed part from working.
     
  5. Glyn1959

    Glyn1959

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    Hi thanks for the replies. It is a timer fan and I have just tried it and it went off after 25 mins. Based on this I can only assume that the sparky didn’t test the timer based on muffking’s reply. Does that make sense?
     
  6. EFLImpudence

    EFLImpudence

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    Glyn,

    L1 , L2 & N are just markings on the plastic.
    They have no bearing on which wire is connected to them.

    It could be A, B & C.
    They are just three switches operated at the same time?
     
  7. Glyn1959

    Glyn1959

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    Hi just to clarify are you contradicting what muffking said?
     
  8. EFLImpudence

    EFLImpudence

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    Yes.

    What he said only applies if you connect the wires going in to the switch with different wires coming out - whether they are in L1, L2 or N is irrelevant.
     
  9. Glyn1959

    Glyn1959

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    That’s clear. Thanks for that
     
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  11. muffking

    muffking

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    That's what I meant by L1-L2 reverse. I could have said L & SL reverse, but the OP may not have understood, plus we don't know out of L1 & L2 which is L and which is SL, so I simplified it as an L1-L2 reverse on a timed fan makes it run only when the light & isolator are on.
     
  12. jj4091

    jj4091

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    Yes but he is talking about a triple pole isolator not a light switch, so it does not matter if you reverse them as the output of both terminals is always live with the switch turned on, there is no live or switched live. just 2 lives.
     
  13. EFLImpudence

    EFLImpudence

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    This is getting confused. There is a permanent live and switched live.

    Here is a simple diagram:

    upload_2020-3-23_12-5-47.png

    You must connect the terminals from the light to the appropriate terminal on the fan as shown.
    The isolator could be three connector blocks so obviously it wouldn't matter which you used for which wire.

    I have not marked the isolator terminals as it doesn't matter which is used.
    Whether N, L1 or L2 for the N, PL and SL doesn't matter, although obviously we would use N for Neutral.
    All that matters for correct working is that the terminals at the light are connected to the appropriate terminal on the fan as shown.

    I have not used colours as it doesn't matter what colour they are, although obviously we use the colours to signify what the wires do.
     
  14. jj4091

    jj4091

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    Ah, then the problem is that I would always instal the isolator before the light switch.
     
  15. EFLImpudence

    EFLImpudence

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    Then you don't need a triple pole switch and

    it negates the usual reason for having a switch at all.
     
  16. muffking

    muffking

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    I agree. I always install the isolator from the L, SL & N at the light fitting or junction box so the customer can isolate the fan without affecting the light.
    FWIW my go to isolator is a Click grid switch with fuse carrier as most fan manufacturers want it fusing down to 3A.
     
  17. winston1

    winston1

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    They are wrong. The fuse is to protect the cable not the fan.

    Neither an isolator nor local fuse is required by the regs if it is on the lighting circuit.
     
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