Sensor to tell me when something looses power

@bobby Could you just do this? I assume the circuit loses power right?

Get something like a Zooz current monitor, they make a heavy duty one that goes to 15-20 amps. Monitor it for current/power/voltage/what ever, it's actually not important.

Now you're going to say, but it loses power dummy, I can't monitor it! But aha! When it DOESN'T reply you've lost power.


How can you detect "does not reply" in RM?

I can see how you could write a driver for that, like a simple, single device version of Device Watchdog, just to ping it at the network layer periodically, or do a refresh, and change state if no reply in $threshold seconds.

I have a ZigBee Door sensor that also senses Temp in my Freezer. I have had this in my freezer for over a year now. I have a Notification App setup to notify me if Temp is higher then X. Been working great.

1 Like

I have same setup with iris close/open sensor measuring temperature and also checking if door is not open too long.
Battery last over year even inside freezer



Yup I'm going in about a year and a half on battery. Easiest way to make sure freezer is still running.

1 Like

I have Iris v2 Motion/Temperature Sensors in my two refrigerators and freezers. I have a rule that notifies me if the temperature rises above a certain level. If you’ve ever had an issue with a refrigerator door being left open, this is a solution. I prefer this over using a contact sensor, because that just looks too ugly.

1 Like

It is plugged into a GFCI outlet. I know the instructions say not to but you go to war with the outlet you have, not the outlet you want. plus it only blows about once or twice a year.

I did end up just buying a power off siren that plugs in to the same outlet. In my heart I want everything to hook up to my home automation system, but in my head I understand that not everything has too. But I am going to look into the temperature monitor. I didn't think one would be able to transmit out of the freezer.

How old is the GFI? Technology has changed in recent years and they are much better than they used to be. I had one in my garage that controlled all my outdoor outlets and it started tripping more often. I replaced it and so much better.


Its from the 80's, it controls the garage, back yard, and both bathroom. I'll looking into changing it, thank you.

1 Like

My downstairs powder room was on my garage/outdoor circuit and rain during holidays would trip my GFI as my outdoor lights got really wet. This was super annoying so I moved my powder to another circuit. Fortunately I have a crawl that made it easy but something to consider if you are able.

We found that the best way to reliably monitor power loss in real time is through a simple 12 VDC power supply connected to a Z-Wave dry contact sensor, more details here:

Aeotec discontinued their dry contact sensor but they added this functionality to the latest Door Window Sensor 7 so that should work here.

1 Like

You do something like this, works with Zooz plug pretty nicely

  1. refresh() on device
  2. wait event device, energy duration or timeout
  3. If energy duration > last energy duration == OK
  4. If energy duration < last energy duration == Power failed, but returned
  5. If energy duration == last energy duration == power out now
  6. Save to energy duration to local variable

if would be really easy if something was set to indicate timeout on wait condition/wait event.

If you can't do energy duration, energy, kWh is the same....maybe that works better. Both are resetable so you could just reset them to 0 and make sure it's incrementing and readable.

1 Like

There are a few variation of this method in the post that @ogiewon linked to above. Some have retrofitted a Samsung leak sensor and other like myself have used the Ecolink contact sensor that has extra screw down connectors that can be used to connect wires to a relay. A LOTsimpler than it sounds and it has worked reliably and instantly for me...without fail. Below is a link to the same post but further down into the thread where simpler options are discussed (the initial discussion is a bit more technical).


If you have another outlet available in that outlet, this is a lot easier now thanks to a recent update. You can use theHubduino project to connect a $5 ESP8266 board to the other outlet via a simple USB wall-wart. New functionality with those devices has built in presence detection. So, when the power fails, the board fails to check-in with the hub on it's regular schedule and the driver changes the board to "Not Present". No special wiring necessary. No battery powered devices necessary. You will get a report to Hubitat within the time of your configurable timeout when the power fails for that circuit.


Oh, I think there's a better way to do it. How about this? It takes 2 rules, but maybe is easier to understand?

Rule A:

  1. run rule "lostPower" delay 10s (cancel)
  2. refresh()
  3. wait for event energyUpdate
  4. cancel delayed actions

Rule lostPower:

  1. Do actions you want on loss of power
  2. etc

If the 2nd rule runs (lostPower) in my example is means the refresh() never returned anything. Rule A runs on a scheduled trigger, and not the wait has no timeout. Waits are canceled when the rule is run again. (per the docs)

This is an old thread, but I thought I would contribute a new idea that is super easy to do: I use a Homeseer HS-FS100 with the light sensor (you can optionally use it as a water sensor with different cable). My GFI outlet in my garage has a light on it and I stick the sensor onto that. As the senor is battery operated it happily tells me when my Christmas lights have tripped.
The sensor also has a buzzer built in to notify me.

I also use the same sensor on my clothes washer and dryer to notify me when the cycles are done - way more reliable that my former wink motion sensors which triggered every time a nearby door opened, or when the door on the washer/dryer opened.


Hi. Are you sharing this RM code like a good little open-source idealist, or is it proprietary (boo!), or have you already posted it and I am just not seeing it?
I am trying to get control of my fridge and this sounds like a good start. Thank you!
Reed McHeyser

I don’t see any indication that he’s using RM. Sounds like he’s using the built-in ‘Notifications’ App.

This is a great solution for monitoring power loss. This Ring range extender has a built in battery that can notify you when the power switches from the wall (mains) to it's internal battery. Props to the developers who created the drivers for it.