I need an (off)-on or an (off)-on-(off) "push-to-break" switch for residential use. Does that exist?

[mrking3000]

I have a humidity sensing exhaust fan in my bathroom. When the fan has power and senses humidity, it will run the fan until the humidity is removed. If you want to turn the fan on manually (in a stinky situation) you can switch the power off momentarily and then back on and it will run for a pre determined amount of time.

In order to make the fan dummy-proof and to prevent mold from growing, I do not want to give users the ability to turn off power to the fan. I could just eliminate the switch and the humidity sensor would take care of the rest, but then the user would not have the ability to momentarily cycle the power to run the fan manually when there is stink but no humidity.

So what I need is a switch that always springs back to the on position. I have found this type of switch in different physical styles that won't neatly work with a wall plate. I need it to be a typical residential/commercial rocker or toggle switch.

The closest I have come to such a thing is the Leviton 1256 but it's center-off instead of center-on. Is it possible to reverse the function of the switch? Or is there another switch out there that would work better? Or is there another more elegant solution all together that I haven't though of?

 

[David Prosser]

A 2 way switch with L1 and L2 linked may work as operating the switch would momentarily break the circuit. Depends on how long it needs the power to restart.

 

[Lucien Nunes]

The OP is in the US so the available selection of switches will be different. Might be worth moving the post to the US forum section.

If.you have room for a small relay you can invert the function of an off-(on) momentary push-to-make switch using the relay's normally closed contact.

 

[ackbarthestar]

Sound as though you require a press to break (N/C) push button switch that auto resets. Wire this in series with the existing extractor circuit.

 

[snowhead]

It's a Domestic switch that's easilly available in the U.K , Push to break or momentary, but as Lucien may not be in the U.S style of switch.

MK K4915WHI Grid Switch Push Break 20A

<p>The MK Grid Plus range is a modular system with items available in a range of finishes. The items are easy to fit as they simply clip in to place from the front of the mounting frame. </p><p>The MK K4915WHI is a white, 20A, 1 Way, Double Pole, Push to Break Retractive Switch Module. This...

www.tradesparky.com

 

[Megawatt]

It's a Domestic switch that's easilly available in the U.K , Push to break or momentary, but as Lucien may not be in the U.S style of switch.

MK K4915WHI Grid Switch Push Break 20A

<p>The MK Grid Plus range is a modular system with items available in a range of finishes. The items are easy to fit as they simply clip in to place from the front of the mounting frame. </p><p>The MK K4915WHI is a white, 20A, 1 Way, Double Pole, Push to Break Retractive Switch Module. This...

www.tradesparky.com

I would have to agree with @Lucian. They make such switches but they are used exclusively for industrial applications so I’m not sure you will find what you are looking for in domestic applications, which wouldn’t fit in your box as a normal switch would.

 

[Megawatt]

I have a humidity sensing exhaust fan in my bathroom. When the fan has power and senses humidity, it will run the fan until the humidity is removed. If you want to turn the fan on manually (in a stinky situation) you can switch the power off momentarily and then back on and it will run for a pre determined amount of time.

In order to make the fan dummy-proof and to prevent mold from growing, I do not want to give users the ability to turn off power to the fan. I could just eliminate the switch and the humidity sensor would take care of the rest, but then the user would not have the ability to momentarily cycle the power to run the fan manually when there is stink but no humidity.

So what I need is a switch that always springs back to the on position. I have found this type of switch in different physical styles that won't neatly work with a wall plate. I need it to be a typical residential/commercial rocker or toggle switch.

The closest I have come to such a thing is the Leviton 1256 but it's center-off instead of center-on. Is it possible to reverse the function of the switch? Or is there another switch out there that would work better? Or is there another more elegant solution all together that I haven't though of?

I advise you to go to your local electrical parts house. I don’t think you will find this switch at Home Depot or Lowe’s. Good luck

 

[mrking3000]

It's a Domestic switch that's easilly available in the U.K , Push to break or momentary, but as Lucien may not be in the U.S style of switch.

MK K4915WHI Grid Switch Push Break 20A

<p>The MK Grid Plus range is a modular system with items available in a range of finishes. The items are easy to fit as they simply clip in to place from the front of the mounting frame. </p><p>The MK K4915WHI is a white, 20A, 1 Way, Double Pole, Push to Break Retractive Switch Module. This...

www.tradesparky.com

Thanks for all the replies! I'll probably try a push button with normally closed contacts and I'll drill a hole in a blank wall plate to mount it next to the light switch.

I am very curious though. In what situation is this Lucien push break switch used? It's exactly the functionality I'm looking for. If I knew why people normally buy this switch in the UK that may help me track down a similar one in the US.