Bathroom vent automation

My household has a habit of forgetting to turn of the bathroom vent. So, I want the vents to turn off after X amount of time. I have a few questions about this.

  1. If I were to get a zwave switch, what kind would I need? I’ve been slowly rolling out GE switches for my lights/fans, would a standard light switch be ok?

  2. Since, I really just want it to turn off after X amount of time (probably 15 minutesish), is there a better alternative? Like dumb a switch with a timer or something.

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I’m using core for this exact scenario. I have GE switches, a toggle for the fan and a dimmer for the light. Here’s the core piston…

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I’m using a GE smart switch, an iris contact sensor, and an iris motion sensor… Yeah, probably overkill! But leaving the fan on for hours is expensive… Think power to run it and it is sucking air conditioned air out of my house!


Which GE switch are you using? the 12722 or the 12730?

I used a dumb intermatic wall switch. Check it out at amazon.

Keep in mind that you bathroom receptacles should be on a 20A circuit and if the bathroom is on a single isolated run it the fan might also be on 20 amps which would mean the fan switch would need to handle 20 amps. You can figure this out in two ways easily. Method 2 would be more accurate…

1 - Look at the wire, if it is 12 gauge, it is likely 20A.
2 - Figure out which breaker turns off the bathroom fan and see if it is a 20A breaker.

I think most of the smart switches are 15A. Anyone know of a 20A one?

tagging @JDRoberts

@Navat604 or one of the other electricians in the community could say more about the requirements. But there are a lot of options for 20 amp control, most commonly an in wall micro. The LFM 20 evolve relay is very popular, and it’s on the official “works with SmartThings” list.

On the other hand, if the vent is the only thing on the switch you may be able to use a motor switch, I honestly don’t know how that works, but one of the wiring experts will. :sunglasses: ( I know the device features, but not the code requirements.)

A standard bathroom vent fan is only drawing about 60 watts. That’s only 1/2 amp.

A standard GE smart switch handles this just fine. I’m running three in my house, no problems.

My GE switches are the older version of the 12722… mine are 49657.

Just for a comparison…

This bathroom vent from Panasonic model FV-08VQ5 is a 60 CFM fan. 120vac 14.70 watts pulling a mere 0.12 amps. This is a rather nice fan and is more powerful than a typical one found in average homes.

This attic fan has a 1/3 hp motor which is 248 watts or 2 amps when on high.

I have each of these on a GE 49657 on/off smart switch. I have no problems running either of them.

@JDRoberts before you say anything about running a large fan motor on a regular smart switch… it is set up like this. :innocent:

—> 120vac in —> smart switch —> high/low switch —> fan motor.

The difference in electricity to the fan is controlled by a high/low switch.

Yeah, just from an engineering standpoint it literally depends on how things are wired. If there’s only one switch on the entire circuit then it would be carrying the full load. But if the circuit is running multiple outlets and switches, you just have to look at the draw rate. But again, I have no idea what code requires these days for a bathroom. :sunglasses:

I get it, but it could still be against code. It was just a heads up.

If the bathroom is not on a dedicated circuit than it likely shares a 20A circuit with all the other bathrooms (receptacles) and taps off the room next to it for lights / fan @ 15A.

Yeah, it’s all on the same circuit… but the one switch controls only that one bathroom fan. So, it only feels the load of that fan, not the rest of the circuit.

Also, the entire bathroom, by Alabama code must be on a GFCI between the panel and the first switch.

Point it, the switch is rated at 15 amps. The fans is pulling 0.12 amps. That is very much within the power rating for the switch.

Code states that every element on a circuit must be rated for at least the amperage of the circuit breaker. Since you must have at least 1 20A outlet in a bathroom, most electricians pull a single 20A circuit from a 20A breaker to the bathroom, and then branch off that circuit to a 20A GFCI outlet, lights, fan, etc.

If this is how your house is wired, code states you must use a switch rated for 20A and at least 12 gauge wire for your fan. Regardless of how much amperage the fan draws. This is because if there was a wiring fault at some point between the switch and the fan which pulled more than 15A but less than 20A, the switch would fail before the circuit breaker tripped.

The alternative would be to pull a 20A circuit for the bathroom outlet, and a separate 15A circuit for the lights and fan. If your house is wired this way, you are free to use a 15A switch.

In practice, however, using a 15A switch downstream of a 20A breaker for a hardwired 60W (or whatever) fan is pretty benign. Only you can judge your tolerance for this sort of thing. I would recommend an AFCI circuit breaker (in addition to your GFCI outlet) as a belt-and-suspenders approach.

Really? I think that’s well above and beyond the NEC. NEC is that all outlets and any light fixture within a certain radius of a bathtub or shower must be on GFCI. But other fixtures (including above a sink) GFCI is optional.

Or at least that’s the way it was when my house was inspected 2 years ago… I should go back see if it’s been updated.

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You guys have now got me worried, I was about to do the same as others with a GE 12722 switch on my bathroom fans and now I’m not sure it’s going to be up to code.

I know the master bathroom, upstairs bathroom and downstairs half balf are on the same 20amp circuit with one GFCI outlet but I don’t think the lights are on the same GFCI chain…

When I was building my house 2 years ago I noticed that there was not a GFCI on both outlets above each sink. I asked the electricians and this is what I was told.

The GFCI must be between the panel and the first switch/outlet. I honestly can’t remember if the breakers are 15 or 20 in the panel for the bathroom circuits. They are most likely 15 amp. I just don’t feel like going to the garage right now… lol.

Also, each bathroom has 2 independent circuits. Fans and lights on one… and outlets on the other. Each with a GFCI between the first device and the panel.

This has always been my rule of thumb about breakers and power draw… take for example…

In my garage there is an a single 20 amp outlet on each wall. Each outlet is the only device on that 20 amp circuit. I had them installed this way because of the equipment I use in the garage.

Plugged into each outlet is a 15 amp 10 plug power strip. One outlet actually has two of these.
At no point will the breaker in the strip allow over 15 amps, thus keeping me at the 75% threshold for total current. For the one that has 2 power strips (I know, I shouldn’t do it), each strip can pull up to 15 amps, but the outlet will pull up to 20 amps. So if I’m pulling 10 on each strip I’ll pop the 20 am breaker… that tells me the combined power is to much for the circuit.

Basically, step down the breakers from the panel to your power draw, protecting the rest of the circuit.

Right… I think we are saying the same thing. Every outlet (regardless of location) and any switches that control light fixtures near (or in) a shower or bathtub must be GFCI protected. Usually this means using a GFCI breaker in your panel, or running the circuit to a GFCI outlet first, and then on to the applicable light switches.

Other light fixtures in a bathroom do not need to be protected to meet minimum code.

Totally. In your case you’re welcome to use 15A switches because your electrician pulled separate 15A circuits for the lights and 20A circuits for the outlets. So your 15A switches are protected by 15A breakers.

In most cases (mine included), I only have 1 20A circuit breaker to each bathroom, so to meet code I must use 20A switches.

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I have an old house so a single 15amp circuit runs the upstairs bath and all three bedrooms, bath electrical hits a gfi and branches but the lights and fan overhead run off the upstairs hall light. My lights and fan are controlled with a dual relay and dual paddle single gang switch. My electrition brother gave me a lengthy spiel on why this was all to code, I got bored and started flipping the switches…

On another note, I was pulling over 50 amps on a 20 amp circuit for my Light-o-Rama display back in the day. Never with all light channels on at once, nothing ever got hot or blew. I have zero faith in readings on these things, either they are all INSANELY overrated for our safety, or they just suck at their job. Oh this was a clean run to a new breaker in my panel too.

In the “ran for years, we never had a problem even though it wasn’t to code” category…

Just sayin’… :wink:

So if only one 20A circuit exists in the bathroom, would it be against the code to downgrade the breaker to 15A to bring the zwave switch within protected amperage range? :wink: Everything past the breaker needs to be at or above the breaker amperage level to be protected. Having a 12AWG/20Amp protected by a 15A is not against code, I would assume. Of course, no one would run more expensive 12AWG wire for 15A circuits, but we have a special circumstance here. @NorCalLights?

I am not an electrician, but I think it is against code. It calls for a 20A receptacle within 3 feet of the sink because a majority of blow dyers will pull over 15A. There are a lot of 1800 watt + dryers out there. 3 ft to the sink as the cord can be hazard.


I just put the 100CFM version of this in my renovated master bathroom. The thing is ridiculously quiet compared to my other two.

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