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Bathroom extractor fan only works when light is off! (pictures and video included)

Discussion in 'Electrics UK' started by jonnythedent, 29 Dec 2019.

  1. jonnythedent

    jonnythedent

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    Hi there

    Recently noticed that the extractor fan in the bathroom had slowed down when light was on (LED lights on ceilng) but then worked fast again as soon as light was off. Thought it was only a simple fan problem so I decided to change the fan today.
    An original fan was Vectaire mf100t which is now discontinued, so I bought a Manrose gold 100t instead today at B&Q.
    My bathroom fan and light has a fan isolator switch with a separate pull cord switch. (i.e. the fan and light come on at the same time).

    Replaced a fan and re-hooked up all the wires into the fan (L, SL and N), but only found that when I pulled a cord to turn on a fan/light, only light came on but a fan didn't work.
    When I pulled a cord again to switch off the light, fan started working (but at very slow speed. Unusable speed) and light didn't go off completely but flickered.
    Can't really figure out what the problem is - could it be a pull-cord switch defect or some circuit fault/poor wiring? No loose connection that I can see at this stage.

    Any help will be grately appeciated. Thank you in advance. Jon

    (inserted pictures are the new fan, pull cord switch and isolator. A video of problem here ).
     

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  3. JohnD

    JohnD

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    sounds like a high-resistance joint. Probably a loose connection. Start at the switch, then the ceiling rose, then any others.

    A multimeter would be invaluable.
     
  4. jonnythedent

    jonnythedent

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    Thanks for your reply John.
    When you say the switch, you are referring to a pull cord switch?
     
  5. JohnD

    JohnD

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    any and all switches.
     
  6. flameport

    flameport

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    Unless Manrose have altered their PCBs recently, you have wired it up incorrectly.

    Pictures of the switches show the black core used as Neutral, and the fan has the black core in the centre, which is not the neutral terminal.
     
  7. jonnythedent

    jonnythedent

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    Hi there
    Thank you for your reply.
    The black cable is in SL, grey in N and brown in L.
    I was simply guided by a video on youtube () - the same model and at 2:16, you can see the guy putting all the cables into the fan PCB.
    As you can see, I'm a total novice in this - can you perhaps advise me which cables should be where?
    Thank you
     
  8. Bilabong007

    Bilabong007

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    Grey to switched live
    Black to neutral
    Brown to perm live is a guess

    Check the cable at the fan with a meter to confirm
     
  9. SUNRAY

    SUNRAY

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    I've just fitted a similar unit and you have terminated the cable as: Brown = Live, grey = Neutral & black = Switched Live. However in the back of the isolator switch it looks like the blue Neutral has a black wire associated with it, implying the black wire is Neutral.

    Without being able to accurately identify all the wires in the isolator switch and for that matter the wiring at the light I will guess you need to reverse the black and grey wires at the fan. I think the cable should be terminated as: Brown = Live, grey = Switched Live & black = Neutral.


    Edit: I started my post about 10pm and got side tracked with arrangements for tomorrow. I see other posts saying the same thing.
    Haviing looked at the isolator again, if as I predict the choccy block in the pull switch has a black and a blue I reckon it confirms the wiring changes offered above.
     
    Last edited: 29 Dec 2019
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  11. JohnD

    JohnD

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    You've really got to find out what the cables are. You can't go by colours and you can't go by guessing.
     
  12. SUNRAY

    SUNRAY

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    Looking at the isolator switch I find it hard to come up with any other circuit than this:
    upload_2019-12-30_0-10-12.png
     
  13. jonnythedent

    jonnythedent

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    Wow thats brilliant. Im just overwhelmed by you guys input and help! Really appreciate it. Was lying down on my bed and thought i would open up the isolator again. Cant open the fan as a baby might wake up and missus will kill me!
    I have checked now in the isolator that brown in top L1 common, brown in bottom L1, grey in top L2 and bottom L2 common, blue and black are in top N. Pictures attached. Thank you guys
     

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  14. huggybear

    huggybear

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    Hi Jon,

    Looks like everything will work correctly once you make the changes inside your fan.

    I have noticed that your isolator switch looks like it has a metal face in the photos. If so, you need to connect the earth wires into the earth connection on the switch face. The screw is missing, but you may be able to use a screw from one of the unused connections of the switch.

    Regards,
    Huggybear.
     
  15. Taylortwocities

    Taylortwocities

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    Hindsight is a wonderful thing but, next time, photograph connections before you disconnect anything.
     
  16. jonnythedent

    jonnythedent

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    With all the love and help, the fan and lights are working well now guys. Really appreciate the help and advice.
    As you guys pointed out, it was the misplacement of black and grey cables.
    Thank you all
    Jon
     
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  17. SUNRAY

    SUNRAY

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    You're very welcome and thanks for letting us know it's resolved.
     
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