John_Crighton:
It may not be relevant to this thread as I’m in the UK, but in my experience it can be OK to use a dimmer with an extractor fan.
This is because extractor fans often have a separate power supply to ‘run on’ after the light is off, meaning they don’t take their supply from the lighting circuit.
Not sure if that applies to the USA though.
You should never use a light dimmer switch for a fan motor. If the fan is wired in such a way that it is not actually drawing current from the circuit controlled by the fan then that’s an entirely different situation.
If the fan is just on/off, not variable speed, you can probably use a regular on/off switch as long as all the other ratings match.
Continuing the discussion from Fan Light Dimming - Aeon Labs Aeotec Z-Wave Micro Dimmer :
Thanks for the shout. Yeah, basically you need to read the manufacturer’s directions for the fan, and check that against the manufacturer’s directions for the dim control.
Rate controls For home use are usually either TRIAC or VFD (Variable frequency drive). A TRIAC controller varies only the voltage. This is what’s typically used for a dimmer light because that’s exactly how you make the light brighter, you give it more voltage.
A VFD varies both the voltage and frequency.
But more importantly in this context, is how the dimmer knows to turn itself on. The short answer is the dimmer switch itself, if it uses a TRIAC, is very sensitive to changes in the voltage, and basically it can get confused …
This applies in the UK as well:
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