Bathroom vent automation

I guess I’m screwed!

To Get back to the OP…

Yes, you can use a GE smart switch.
Yes, there are alternatives for programming.
There are lots of apps you can use.

An on/off switch is usually fine for an on/off fan as long as all the other specs (amps, etc.) are OK.

Never use a dimmer switch for a fan.

If the fan has low/medium/high settings or variable speed, then you need to get a fan switch.

As far as networked versus non-networked with a timer, The nonnetworked will usually be cheaper and more reliable, but you won’t be able to set up fancy automations with all kinds of different logic like light sensors and humidity sensors and that stuff.

I ended up going with a $20 nonnetworked motion sensor switch for a small bathroom because it has foil wallpaper, tile on the shower, and a big mirror, and I was having a terrible time getting signal into the room, regardless of protocol.

So you may find that you use different solutions for different rooms, just depending on the specific conditions. :sunglasses:

A strict electrical inspector would say this is true. You may not use a 15A switch protected by a 20A breaker.

Again, your own tolerance for risk is your own tolerance. A 15A switch doesn’t immediately burst into flames when you pass 15.2A through it. Reputable manufacturers build tolerances into their switched for edge cases. Overloaded switches fail over time because the switch pads are not designed for the stress of opening and closing under high loads.

The real danger is 14gague wire on a 20A breaker. If your house is wired with 20A breakers but with 14gague wire, that’s a big problem. Far bigger than a few 15A switches with hard wired loads under their rated capacity.

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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.

This applies in the UK as well:

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Yes, I’m in the UK and that is how I have wired mine.
The lighting circuit can just be a trigger to turn on the fan and as @John_Crighton has said that fan then has it’s own supply.
So I have wired my Dimmer into the light ‘trigger’ and use a Humidity Sensor to turn on/off the light trigger.
The fan then runs on for the minimum settable time (2 minutes for mine) when the Dimmer turns off and then turns off.

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I put this one in, absolutely love it!

If you are building your house. You have control of how you want the wires going into each room. I would never have lights and receptacles in the same circuit even if my municipal allowed it. Last thing you want is your hair blower trips the breaker and you are in the dark trying to get out of the room to reset the circuit.

Highly doubt it that your inspector is going to give you a hard time having a 15amp switch on a 20amp breaker knowing the max load of that switch is not going over 80% of that 15amp switch. I don’t think there is a problem with 15amp zwave switch on 20amp breaker as long as you know the fan/light is not drawing crazy amount of current. I would check with your local law of course. Don’t want house fire on this forum caused by smart switches.


FWIW - I’s nearly impossible to find a timer/fan timer / etc that is 20 amps. Even looking at the Broan ones, which are specifically designed for bath fans all I saw were 15. They do have one of those 3 switches in one gang that is 20 , surprised they can get 3 20 amp switches in their.

Not saying their are none - but I spent some time looking and saw none. I have one of the solid state count down ones, I doubt if it’s 20, nor do I care :slight_smile:

I have an old one where you that is spring powered, bought it for a project and never used it, will need to check it.

They’re all 20A breakers with 12AWG wire, the switch is ONLY connected to the extractor fan which is similar to what others have described so like 1/2hp or very low wattage. I assumed because this is the only load on the switch and is significantly lower than what the switch is rated for this would be fine.

The comments in this thread though have got me worried though that this is not up to code.

Actually as opposed to what others have said - you are OK - If needed I’ll search and find the code. 20 amp circuit can use 15 amp switches as long as the load is less than the 15amps. It still must have 12ga wire.

Similar to allowing 15 amp receptacles (as long as it is more than 1 on the circuit) .


My Home Depot has 20 amp spring timers. People use them around here for pool equipment.

And Leviton makes a whole line of countdown timers with presets (Five minutes, 10 minutes, 15 minute, etc.) for up to one HP motors on 20 A.

And Sylvania makes a digital one:

None of those are directly integratable with ST, but they should be findable if you just need a timer function for a 20 amp circuit. :sunglasses:

I have 1 question? Does anyone seriously think that the average person that buys these switches is aware of or even knows of the code about a 20amp current in a bathroom? Probably not, they see that cool zwave switch hanging in lowes assuming a switch is a switch. I can tell you without any doubt most of these switches that are bought are put in by the average diyer. Most of the people that are putting them have no idea this forum even exist, so they would never see this or any other post.

The vast majority of them are more the probably have changed other switches in there house, so if it posted in the instructions some where it wasn’t even opened to read ( because to them a switch is a switch)

Just saying I see post on here and other places about being code. And vast majority of stuff done by homeowners would no where be even close to meeting any code. And it’s done by them for one reason only. The biggest reason of all.


Based on consumer surveys, that’s not the usual reason for installing Z wave switches. Because those switches are way more expensive than the ones that they’re replacing. You can put in a non-networked timer switch or motion sensor switch for less as well. So I don’t think replacing these light switches is about saving money. It’s about cool Tech or it’s about accessibility. Or as part of a DIY security system.

It’s precisely because this kind of networking isn’t that simple that the people doing it are more likely to read the specs.

No question there are people doing it against code. I especially hear about people removing a GFCI receptacle and replacing it with a Z wave one. But I think less than people installing nonnetworked equipment.


They are just incredible fans. Barely can hear them. Now that I see that one, I probably would have spent the extra $10 to have a smaller hole in my ceiling, but no worries. Congrats :slight_smile:


Downside with the smaller hole is actually a bit lower air flow I believe, and actually I bet it’s a bit more wind noise due to the smaller size. But it’s 100000000 times quieter than my old apartments fan!

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Ah, yes, that makes sense. Mine barely can be heard, and we can sleep in our bedroom with it on, as you cant really hear it without trying. We use the 100CFM one, and it makes me regret putting a slightly cheaper model in elsewhere… the cheaper ones are loud!


Your right about this. Would this clause apply to a light that is just one a switch? It sounds like it.

Yes - as long as the wire has 12ga wire, some say it’s a quirk in the code, but it’s been that way forever. Now it actually depends on the light fixture (luminaire (sp) in technical terms), if it was rated and you could put in a 2000w light bulb. More practical would be multiple lamps that could total over the possible allowance.