For my 240v power dryer, I use a z00z temperature/humidity sensor taped to the side of the dryer and motion sensor in the room that also reads the temperature but for entire laundry room. I also have a contact sensor on the door. My requirements are little different. I want to be reminded when the dryer has clothes inside not necessarily the moment it completes. I have a couple of Fire-Tablets acting as displays in my house that shows the status of the laundry and dryer (on/clothes inside). When I start my dryer the side of my machine begins to quickly get warm. When the sensor on the side of the dryer is 4-degrees warmer than the temperature of motion sensor (the temperature of the room) I have a rule that turns on a virtual switch that indicates the dryer is on. It takes my dryer normally 2 to 4 minutes (depending on how much clothes is in the dryer) to be on before the virtual switch is triggered. I use the contact sensor with a rule to determine if the dryer is off and clothes are out of the machine. This has worked perfectly for me now.
I wonder now, what if I did the opposite to notify hubitat the dryer is completed? ... if I create a rule that stores the highest temperature reading during the on-cycle in a variable then continue comparing that to the current temperature of the dryer (the z00z sensor on the side of the dryer)... if the current temperature (from the z00z sensor) drops by 1 or 2 degrees of the highest temperature reading when turned on, that would be the indicator that the dryer has completed. I think that would work but it really depends how long the dryer takes to cool down 1 or 2 degrees...I'm not sure. When I have time maybe I'll look to modify my rule to do that. Though I need to see how long it does take the dryer to cool down by 1 or 2 degrees.
I use the method outlined in this thread. Of all the methods I've used over the years this has been the easiest and most reliable. (vibration sensor batteries drain due to constant vibration, temperature sensors have a delay, contact sensors are ugly). This method triggers open/close on contact sensor as soon as my dryer starts and stops and is extremely reliable and hidden in the back. Installation was super easy. Took off hte back panel, put it around one of the legs of the power and put the panel back on.
This method can also be used to monitor status of other devices if needed.
I just sold the last of mine.... Actually really happy with the iotawatt. (simply because I don't have to run multiple units as well as I can graph and output to influx_db if I want to.
ya i looked at it and decided i dont need those features and mine is working and i dont really want to open ujp the box and disconnect and reconnect clamps to my hot mains. if i can help it.
I am glad this is working for you too. I have been using this method for a while now and it works great every time. It is hidden and triggers every time 100% because the relay closes when power flows through the coil. So it can sense power on really any appliance that is running.
As @gavincampbell has done he used the external plugs on a contact sensor to close. Then the solution is truly wireless. I used the relay method, but really anyway to monitor the relay's status is all you need to do. You don't have to modify your dryer at all it is just pop it on the wire and set the sensitivity and you are good.
The clamps are inductive so nothing needs to be disconnected. I fabricated some cardboard shields to temporarily cover the main wires feeding the panel. Kept one hand in my pocket. Closing the clamps with one hand wasn’t difficult.
Then again, there is my dear departed father in law. He wanted to replace his fused entrance panel with a breaker panel but didn’t want to call the power company to pull the meter. He said a big ball of fire shot out. Blew the transformer and knocked out power to the shopping center. This was before I met my wife.
