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Lights & Fans

whjohnson
Looking for pitfalls based upon direct experience here.

Bathroom inline timer fan on lighting cct comprising of 6 x GU10s fitted with LED lamps, no problem so far.

Customer has requested that a dimmer switch be fitted since the lamps are too bright - Six 5W warm white lamps.

I say 'Not a good idea, since the electronics in the LED dimmer switch could conflict with the electronics in the timer element of the fan motor.

Either way, damage could result, not to mention the extra cost of swapping out essentially new LED lamps for dimmible ones.

So, what happens when we fit a varilight dimmer switch to a cct comprising of 6 IP rated LED GU10s and a manrose 100mm inline timed fan in the loft above?

Am suspecting that the fan motor windings wouldn't be too happy either.

I have suggested instead, that we drop the lamp wattage down to say 3.5W rather than fit an expensive dimmer switch.
  • 0
    It might be OK provided the L to the fan is "undimmed" and only the SL (timer trigger) is via the dimmer - although I can't say I've ever tried it.


    There again the waveform chopping by the dimmer might cause interference with the timer electronics just by proximity, whether the fan is wired though the dimmer or not.


    I certainly agree that lowering the lamp wattage seems like a much more 'elegant' solution though.


       - Andy.
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    The permanent supply to the fan must be before the dimmer. I doubt you will do any damage to the fan, the only question is whether the fan would start at low levels of brightness. An alternative suggestion would be the dimmer for the lights, then start the fan with an occupancy sensor. The fan timer should cover the time someone is in the bathroom without moving as long as it has a sensible time set. 


    Regards,


    Alan.
  • 0
    Maybe I'm misunderstanding this but could the desired solution not be achieved by the use of a modular switch and LED dimmer switch?


    ​A permanent live from a switch spur supplies the switch and fan. The switch provides an undimmed s/l to the fan and dimmer switch. The dimmer switch dims the lights.


    F

  • 0
    As Alan said fit a occupancy sensor or humidstat to control the fan.


    Andy B.
  • 0
    As we all know, the regs state that "Manufacturer's instructions must be followed", so that means that the switched side of the FCU must protect the fan.

    I will ask, does this include both the permanent live and the switched side to be on the 3A protected load side of the FCU?

    If so, that scuppers the idea that we can separate the two to accomodate the dimmer facility.
  • 0

    whjohnson:

    As we all know, the regs state that "Manufacturer's instructions must be followed", so that means that the switched side of the FCU must protect the fan.

    I will ask, does this include both the permanent live and the switched side to be on the 3A protected load side of the FCU? . . . 




    Yes. 

     



    . . . If so, that scuppers the idea that we can separate the two to accomodate the dimmer facility. . . 



    Why? 


    Regards,


    Alan. 

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