Sense Dryer Running or other appliances

I did a thing I used the Zooz Multi Relay's input from the dry contact to detect if the dryer was running. There are a lot of wires in my house from the previous owner being an alarm installer so I found one that used to go to a window and went to where the alarm panel is. I have my Zooz where that panel is.

I put one wire on the dryer's circuit through this thing:

and when the dryer is running it powers a relay and closes the relay. You can set the sensitivity of when it closes the relay with a screw. So it powers on when the dryer is running then you can make it close if the heating element is on or just if it senses any power. It is fully self powered off of the magnetic field of the power going through it.

I connected the 2 wires coming off that to the Zooz and now it "turns on" one of the inputs on the Zooz when the dryer is on. So on the dashboard the switch associated with that input shows on when it is running. All that thing does is close the relay when it senses enough power to trip your threshold but it powers up when power is flowing through it.

One thing that is strange and it could be how my dryer works but the motor that spins the clothes doesn't seem to pull power down the leg that I have this thing on. It only shows the dryer is on when the heating element is running. I haven't taken the time to try to put the other hot leg through the hole because this works just fine for me.

Thinking this could be used for people with fireplace fans or furnace fans or other things too that you want something to happen if said device is on. Other people on Amazon have commented using it to close the relay and trigger something based on their AV receiver turning on. You could even take apart a contact sensor and hook it to this thing instead of the reed switch. It is a dry contact thing it just closes a relay to complete a circuit the same as the reed switch would do.

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Also the hole for the wire to go through is like 1/2" so you can't just jam an entire 220v dryer cable in there you have to just put one leg through. The only annoyance is it is a solid thing it doesn't split open around the wire so you do have to disconnect a wire to put it through the hole.

In my research I found that most dryers the non-super fancy ones... The buzzer part is 120v powered, so I had thought about disconnecting the buzzer, wire up a transformer, then have it close a relay that went to a reed switch. Then I could have a notification when the dryer is done.

I found this thing that didn't involve modifying the dryer so it seemed easier.

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For those with a spare Amazon Echo Dot, you can trigger a virtual switch in HE via a routine in Alexa to trigger on appliances beeping. That worked well for me because I have a bunch of Dots in my junk box (I buy them when there's a 99 cent deal).

The bad news is that the Dot has incredible ability to hear appliances 50 feet away and triggers on all of them. I temporarily limited this by only making an announcement if the washer had recently run. Sometime in 2022, it should be possible to train Alexa for a specific appliance beep.


Thanks for this. I didn't know these existed. I grabbed one off of amazon to play with and just curios if you see this.

I'm testing it on a circuite I rigged up to a light. When I plug it in and the light comes on it powers on the sensor and I can adjust it to be open/closed with the dial just fine.

However when power is cut, I found that the sensor stay's in whatever state it currently is in. So if it were open and I cut power it would stay open and the same if it were closed and I cut power.

I was expecting it to open when power is detected and close if power is cut or below the threshold.

Do you see something similar?

What?! I had no idea they added this to Alexa. I also have a bunch of dusty pucks laying around.

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It should. In your wiring, had you passed both the hot and neutral through the CT or just one?

Just one.. tried with the hot and the neutral (separately).

When I turn on the light, it gets power, and turns to green and closes the circuit. I can adjust the dial so that its opens the circuit (as it doesn't meet the threshold), However once I cut power to the device it doesn't automatically open the circuit back up. It just leaves it in whatever state it was.

I am trying this on a floodlight I'm playing with. Much easier. I am thinking on the dryer when it ends it would reduce the power load (from drying to just beeping) and then have enough power to close the circuit before finally losing power. But I won't know for sure until I mount it in my dryer.

I was also wondering if NC versions do that. This is the NO version.

Oh wait I think I may have got it. I think it was a user error. Yay!!! I got so many ideas.

I've been toying around with an idea for the dryer solution myself. I have my washing machine done with zooz electrical appliance and a contact sensor. That works great. But my dryer is 240 volts and I really don't want to mess with any anything electrical. So, what I have been working on ... or I should say testing... for the dryer is a combo Zooz Temperature sensor and contact sensor for the dryer door. When my dryer is on, the side of my dryer heats up very quickly. So, I placed a bottle cap on-top of the temperature sensor and used trusty old duct tape to tape it to the side of the dryer. I use a couple of strips of duct tape because with the bottle-cap on top, I create a sort of air pocket with the temperature sensor inside of it. I can easily see the temperate rise well over 20 degrees within minutes of the dryer running. That (quick temperature rise) and the contact sensor (door closed) is my indicator the dryer is running. That turns on a virtual switch (Dryer) to on. The second part is to monitor when the door hasn't opened and how much the temperature sensor cools to trigger the dryer is off besides using the contact sensor and indicating off but clothes are still inside (I have mutiple home panels to provide us such warnings). I'm still running temperature baselines on the cooling down or if someone opens the door to put stuff in and continues running the dyer, but it looks promising. After I get the baselines, I need ... in my house it's just me and the wife and it's not like we are doing so many laundries and I need to get more test baselines... also for all seasons as well (I think)... but once I finalize those base lines, I'm going to finish a WebCore script (Hubitat is still new to me... long time ST user) to put it all together. I was thinking about using a second temperature sensor in the room itself to do comparisons... sorta like that Hubitat video on using two Humidity sensors to turn on the bathroom fan. But so far from the baseline logs I'm getting; it doesn't look like its needed. Just throwing out my idea... It's not a tried true and tested solution yet... but as I said... it looks promising so far.

I implemened this current sensing solution yesterday. It took me less than 10 minutes to install it on my dryer.

After unplugging, I took off one screw to remove the small panel on the back. From there I just had to unplug the hot wire, put it through the sensor and then plug it back. Put the cover back on, plugged in the dryer and it works.

This solution is easier than I expected and works REALLY well.

I have it hooked up to a old Fibaro contact sensor that accepts external triggers. So its all wireless and on my zwave network now.


I am glad you got it working, it was super easy to get it working just had to unplug and shove a wire in the hole. Tuning the relay to trigger was weird with really no instructions on the thing. I have done an open collector thing with an old contact sensor taking one apart before and just hooking to the reed switch but that is cool your sensor has external connectors. It seemed like the cheapest and least intrusive way I could find to monitor if it was running.

I thought about if someone had a sump pump or something else like that you could put one on it too then you can see or get alerted if something started running. There is a person who uses them on the Amazon page with arduinos to automate dust collection with their power tools.

In case anybody is looking, these contact sensor also allow for external switches that should work with this solution.

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