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There are a handful of "smart ceiling fans" available that are really expensive (up to $500).

Is there an easy way to just add a smart wall switch with a cheap dumb ceiling fan to get the same result? The fans in question are hardwired, not using any plug.

Some details:

  • Amazon Alexa switch or HomeKit switch, either would be fine
  • Would not need to control a fan light, only the fan itself
  • Would need to also control fan speed. Maybe one switch to turn the fan on and off, and a dimmer switch to control the fan speed?
Helmar
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Lee Whitney III
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1 Answers1

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You probably need a relay rather than a 'smart light switch'. This is because the light switches frequently rely on leakage through the lamp to power the electronics in the switch. With a fan motor, this might not work as intended. You would also risk some damage in using a dimmer to control the motor.

The key difference with a smart relay is that the switching element takes feed and return power directly, providing independent terminals for the load. They can use either mechanical relay or electronic ones - just make sure it is suitably rated for an inductive load.

As an example, LW821. You would typically wire this in the ceiling void, and then have the challenge of how to manage the switch - so you might replace the switch with a LW-RF transmitter (confusingly described as a wire free switch) - rather than trying to come up with a 3-way control.

You will not be able to mount the relay at the switch location because there is no 'common return/neutral' in a normal switch location. Effectively, you need to install a switched spur (and this most likely means some places require an electrician to certify the work).

Lee Whitney III
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Sean Houlihane
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  • What's an example of a smart relay to do this? If it does not replace the switch where does it go? – Lee Whitney III Jun 29 '17 at 07:36
  • You say a normal switch does not have a neutral, however isn't that true only for older houses? My house is about 20 years old and had them (hidden behind an adjacent switch), I needed them to install a WeMo dimmer. – Lee Whitney III Jul 10 '17 at 17:42
  • @Lee, No, not as far as I know. Not on normal UK lighting circuits. – Sean Houlihane Jul 10 '17 at 21:45
  • Sean I'm in the US so that may explain the difference. thanks. – Lee Whitney III Jul 11 '17 at 01:52
  • @Lee - a typical switch in the US does not have a neutral either. It might have a protective ground, but you're not supposed to use that as a power return. – Chris Stratton Jul 11 '17 at 02:42
  • @ChrisStratton why do you believe that's true? It looks like the US National Electric Code was updated in 2011 to require switches to have a neutral. As I mentioned above, it may not be there for older homes. Also the code does allow for a couple exceptions, and electricians can make mistakes, but people can often expect to have it in their home. Another point of confusion is it's often hidden behind an adjacent switch box and may not been easily seen. – Lee Whitney III Jul 12 '17 at 18:01
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    @Lee - first, because a typical actual switch doesn't have a terminal for a neutral, because if this possible code change (which concerns the box, not the switch) was only in 2011 the vast majority of housing stock predates it, and also because of the prevalence of the issue: https://diy.stackexchange.com/questions/41570/why-would-a-light-switch-be-wired-with-the-neutral-wire and https://diy.stackexchange.com/questions/10427/is-it-normal-to-have-a-light-switch-setup-using-only-the-hot-wire – Chris Stratton Jul 12 '17 at 18:04
  • @Chris 1) Not a possible code change, it's definite (without a special jurisdictional exception). 2). I spoke imprecisely. I meant switch box with a neutral wire available, not switches themselves. 3). Neutral wires available in box did not start happening only in 2011. My 20yr old house had them, and it's not uncommon for others of that age. There is some data to support the prevalence of this before 2011. Also common for people to check and miss them because they are pulled back or obscured. – Lee Whitney III Jul 12 '17 at 19:44
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    https://diy.stackexchange.com/questions/61505/ http://www.ecmweb.com/code-basics/switches-receptacles-and-panelboards https://jadelearning.com/jadecc/courses/UNIVERSAL/NEC05.php?imDif=714 Although I agree many historical properties will not have used this approach. I have no idea if historic wiring practices would have made it more or less likely by chance, US being 110V so less 'shared copper' than typical old UK topologies. – Sean Houlihane Jul 13 '17 at 09:18