Reverse Relay Switch (i.e. activating opens circuit, doesn't close it)

This isn’t a Vera-related question, so apologies, but there are so many informed people in this community, I wanted to ask anyway.

I’m looking for a reverse-relay switch (if such a thing even exists), meaning a push-activated wall switch that opens/interrupts the circuit rather than momentarily closes it. Here’s the back-story to explain my question…

I have exhaust fans in the bathrooms of my new home that are automatic humidity-sensing fans. So for normal operation, they are simply left ON, and they activate when they sense humidity. If you want to manually activate them, you have to momentarily switch them off then back on, and then they’ll stay on for a preset time (20 minutes in my case). Pretty straight forward, except for my guests, who invariably see the fan switch on when they leave the bathroom, and switch it off thinking it’s one of the lights, or if they want to activate the fan, can’t figure out how and then struggle when I try to explain it (I know, it sounds simple, but most just don’t get it). So my hope was to install a momentary relay type of push button switch that would actually always leave the circuit closed (ON), and then interrupt (open/break) the circuit when you pressed it, thereby manually activating the fan. This way, I wouldn’t have guests shutting off the fans, and I could put a discreet label on them indicating it’s the fan control so there was just a simple push to turn them on.

So, if anyone knows of anything out there that might work for this, I’d greatly appreciate a response. Thanks.


The google-fu magic phrase is “normally closed momentary switch”.

They might not be something that you specifically have to buy. In my part of the world, switches for wall plates all come as “double toggle” versions, combining a normally-closed and normally-open switch in the same enclosure, and you wire up the connectors according to the behavior that you want.

Edit: correct DT terminology.

Edit: Here’s one: Clipsal 30MBP.