Power socket alarm?

Forums › Home Workshop DIY › Power socket alarm?

johno1234

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#319390 21-Apr-2025 08:11

This scenario got me thinking:

https://www.geekzone.co.nz/forums.asp?forumid=48&topicid=190840&page_no=1791#3366077

Using a home automation smart plug and some sort of routine to periodically confirm that it is alive and on. Bonus would be temperature sensors for ambient and refrigerated space.

We have a holiday home fridge to monitor and our fridge at home is on an RCD circuit that has a test button on a master socket that can get accidentally bumped.

I didn’t find anything obvious with a quick google. All it needs is an alert if the smart plug is not responding or off or optionally if the temperatures are out of range.

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#3366104 21-Apr-2025 09:13

What about a cheap ($28) TAPO H100 hub powered by the plug the freezer is on? If you can't connect to it, you could assume that the power is off.

TAPO also make a Water Leak Sensor (T300) that has metal studs to detect water. You could power a 240vac relay off the freezer plug and connect the normally closed contacts to the studs. The relay would drop out with a power cut and the contacts would short out the studs indicating a water leak. The hub would then send a notification to your phone. Hub just needs to be on another power circuit.

Probably not the geekiest options, more cheap and cheerful, but should work.

johno1234

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#3366108 21-Apr-2025 09:34

k1w1k1d:

What about a cheap ($28) TAPO H100 hub powered by the plug the freezer is on? If you can't connect to it, you could assume that the power is off.

Thanks this is the sort of thing I was thinking of. Basically a dead man's timer where if you haven't heard from it you raise an alert.

It's a shame that T100 is not a smart plug and hub combined but as you say can at least be plugged into the same circuit as the fridge...

Would be cool if the device had internals to allow a temperature probe to be wired in too...

MadEngineer

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#3366113 21-Apr-2025 10:32

Smart Power Fail Alarm & Hub Kit, Smart Home Starter Kit with AC Power Outage... | eBay

There are other out of the box ideas, I've got one of these cameras which seems to reliably let me know when it goes offline:

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MadEngineer

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#3366115 21-Apr-2025 10:44

Shelly EM Scene for Power Monitoring Alert – Lykalyte

Assuming that the fridge has a measurable usage regardless of it operating the compressor

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richms

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#3366120 21-Apr-2025 11:17

Tuya based bluetooth sensors are $4 or so on aliexpress choice deals, the gateway is about $10 - put lithium batteries in the sensor in the freezer - I got mine from marine deals for a very good price on some varta AAA's - normal alkalines do not last very long at -24c

Power monitoring plug lets you see the usage. I have not looked into the tuya automations to see what that can do as far as alerting to too much or not enough energy usage, I just made a page in home assistant with all the sensors and power meters on them. Still working on automating the alerts.

As this would connect to the tuya cloud, you can have them anywhere online and connect to that same cloud login with your home assistant at home and chart the things that are elsewhere.

I have found that my freezer incidents have been when something has fallen during the defrost cycle when it unstuck from the side of the freezer and then pushed the door open, so keeping an eye on temperature and if its running too much is more use than if the power has tripped, as I would generally know about that at home before there was any defrosting.

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johno1234

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#3366160 21-Apr-2025 12:57

The advantage of just polling the smart device so confirm it is alive is that it doesn’t require the house power to be on to power the Internet connection. The disadvantage is that an Internet outage would look like a power outage.

richms

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#3366165 21-Apr-2025 13:09

You can set offline warnings in the tuya app for things. Not sure that the alerts will get thru silent and DND mode tho.

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timmmay

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#3366275 21-Apr-2025 16:05

Instead of monitoring the power you could simply monitor the fridge temperature. That's indirect but probably more useful in some ways. Of course, if the power to the whole place goes out you won't get an alert unless your internet connection and your YoLink hub are on some kind of battery backup.

YoLink temperature sensor including hub. I have a few of their temp sensors and four water leak sensors, the whole Yolink system is great. The range is huge, no problems transmitting out of my fridge, and the temp sensors can transmit from my greenhouse through a concrete block garage to the hub in the middle of my house, 25m or so I guess. They have a home assistant integration, it depends on internet connectivity but it works well. Their own app is very good as well.

They have three or four types of temp sensor. The once I've linked to is the one meant for fridges. They have indoor ones, outdoors ones, with or without screens. They have a new version of their water leak sensor here.

RunningMan

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#3366277 21-Apr-2025 16:16

Existing thread on the same topic https://www.geekzone.co.nz/forums.asp?forumid=73&topicid=318819

johno1234

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#3366287 21-Apr-2025 17:17

Monitoring the fridge temp would be a bonus but the main issue is the power which could go out for the circuit or the whole house. So relying on the internet being up is no good.

jarledb

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#3366294 21-Apr-2025 17:45

I use the iSocket to monitor power to our freezer. You can add a temp sensor to it for alarms as well.

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timmmay

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#3366295 21-Apr-2025 17:45

A small UPS on the internet connection might do the job? Keep everything going long enough for the temperature to drop? Maybe have a VPN set up so you can ping something in the house? That's probably excessively complex though.

johno1234

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#3366297 21-Apr-2025 18:00

Yes that would be the geekzone approach. I’m hoping for the low cost foolproof on though!

timmmay

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#3366311 21-Apr-2025 18:51

You could turn the fridge off and take the food to your main house in a chilly bin. Otherwise something like the iSocket that was posted above might work well, it uses mobile data.

andrew75

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#3366313 21-Apr-2025 19:26

Useful topic. I discovered the other day a mouse had taken residence in the garage feeezer. Second time now in recent years. Must have got itself zapped, fortunately tripped the RCD. Went to the garage to discover a decaying rodent smell + half defrosted freezer. Am looking at options now. I think a temp monitor would be better than a power monitor, plugging the freezer into a smart plug just looks to be introducing another point of failure (and I've had Tapo smart plugs fail before).

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