Inferring a power failure

Hi all, am trying to detect individual circuits' power failures, especially fridges. I have Zigbee power outlets on each circuit, they periodically report in to Hubitat. I thought of 2 techniques: 1 - Test each outlet "last updated" time and date and if greater than 15mins from "now" then it is power failure. Unfortunately I cant find a way in RM of copying that attribute data into a variable to do a comparison on it! Is there a way?
2 - Do a "refresh" on each outlet. Maybe there is a flag that signifies either a success or fail of the "refresh" that can be used to determine power status in a Boolean formula? Once again, does anyone know of such a flag status?
I'm using a C-8.
Thanks for any comments.

Is there a reason why you want to know each outlet’s power failure rather than the whole house losing poser?

Ring Z-Wave Range Extenders will send an event when they switch from Mains to Battery. I have a few of these and use them in part to know if a certain circuit or the whole house lost power. They work extremely well for this purpose.

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You may want to look at the Device Activity Check custom app, potentially for other use-cases as well.

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I had my power being reported every 10 minutes. I had a rule that would trigger off the power changing which it would do every 10 minutes if the power was on. So there was a 15 minute delay at the top of the rule and then if that timer ran out I would ping a couple of WiFi devices that I have and if they failed to reply I'd report a power outage and set the boolean value to true so I knew it had already reported the power being out. Once the power came back on it would report that and reset the boolean value to false.

All that said I ended up getting the Zooz ZAC38 and it makes for a very simple test plus its battery is built in and self recharges so you don't need to worry about it.

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Yep, I have a full house power failure device, but I can do anything remedial if I have no power. If I have only lost 1 circuit due to earth leakage trip then I can take action to reset it before my crayfish and vac-packed meat thaw out.
I'm really trying to get this done without buying more hardware, "her indoors" is touchy when anything arrives in a package these days. But, I may have to.

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Yes, am starting to come around to that option. It looks like it would do the trick, as long as it doesn't bog down my comms or CPU.

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Thats my original thought, only trouble was that it has very intermittent power consumption so it mightn't change for hours. A bit of a too long time scale for me. Looks like a Zooz if all else fails.

That's why I got the Zooz the other way it was my top CPU usage app. With the ZAC38 it doesn't have that issue.

I would be hesitant to use a power monitoring plug on a refrigerator or freezer. If the plug fails you could lose everything in the freezer. I have had a number of such plugs fail from several different manufacturers when there are power surges during power failures. Thus, I do not trust them for mission critical applications such as refrigerators and freezers. For that same reason, I do not want a GFCI outlet for those appliances.

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I totally agree.

The newer plugs also shut down upon a "perceived" over current.
Their perception could be flawed. :slight_smile:

Some will re-close after a set period (ZEN15?).
Still, you are introducing another point of possible failure, ironically, in the interest of reliability.

Perhaps something less invasive, like a current monitoring relay, or the like?

I have one on mine as sometimes my fridge gets stuck in defrost mode. I have a temp sensor in the fridge that will let me know if the temp climbs over a certain value for more than a few minutes (normal in defrost cycle) and if so it will alert me so I can remotely power cycle the fridge. That fixes the stuck defrost for me. It would also alert me if the plug itself failed so in that regard it's a win win for me. The fridge itself (not the plug) also has an appliance surge protector. If the power goes out or spikes it will kill the power to the fridge for 4 minutes after the power comes back on or stabilizes. Then it will resume. Very nice for todays power sensitive compressors.

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As a side note, I'm curious, what temp sensor are you using?

Actually using Aeotec motion sensors (have the test in two different freezers). They go forever on a battery.

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If I have a dumb relay that has a "dry contact output" and is powered by the circuit I want monitored, and the relay's dry contact leads are terminated at an Aeotec Door Sensor Pro 7's dry contact sensor terminals (and the appropriate attribute is set), will the Pro 7 send an open/close changed status to HE when the relay opens/closes its dry contact output due to the circuit's power failing/restoring?

I bet it would.
My Ecolink contact sensor, also with terminals, does.

Ecolink's website is a bit confusing. They show two door sensors and both have the same product number... DWZWAVE2.5-ECO...

https://discoverecolink.com/product/z-wave-door-window-sensor-oem/

...and...

https://discoverecolink.com/product/z-wave-plus-door-window-sensor-diy/

The first one doesn't mention "optional external hardwired device input" on the page or the Installation Manual linked to on that page.

The second one does say "optional external hardwired device input", but it doesn't have a link to an Installation Manual.

Neither have any pictures/drawings/diagrams/etc. that show external inputs.

I've asked Ecolink for clarification.

I have a couple of ground fault outlets that occasionally trip and take out all the outlets connected to them. I put a couple of smart bulbs powered by those sockets and I have a rule that turns on each light and then checks the status to see if the bulb reports on – and then the same thing with off. If it passes, I figure the outlet is OK; if it fails, I get a phone notification. It has saved me a few times.

Here's one I have attached to a temp controller for my wood stove. It sends me a message when above a certain temp.

I only had to turn around to take the pic, since I'm warming my butt in front of the fire.

Thanks everyone, got plenty of trials to do now.
If using smart outlet I was going to use a spare outlet so it cant interfere with my fridge. Would just ask for the voltage reading, if no answer then power is probably failed.
Am currently not using a temperature sensor. Am a bit amazed that a Aeotec motion sensor would survive in a fridge, let alone be able to transmit through the fridge's insulation. I have a spare Smartthings door switch sensor that happens to also transmit temperature, a possibility.
The toggling of smart bulbs is another goodie, only trouble is that the light circuits are separate to the power circuits in my house. Would work if looking for a total power outage in the house but not a single power circuit, unless I plug in a lamp with a smart bulb.
That last PC temperature addition is a real