I need to know if there is a power cut in a building. I have to detect this remotely, because I am usually not present at the building. I need to detect the power outage in less than 24 hours to save the foods in the fridge! The process could be either automatic or manual. I am looking for a creative way to do that which is not that expensive. I am specifically looking for solutions based on using phone calls or internet-connected devices to detect power outage.

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    Set up a webcam and phone app. Preferably the phone app will have a feature that alerts you when the signal goes dead.
    – MonkeyZeus
    Nov 30, 2021 at 14:53
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    Most land lines these days will ring and then go to voice mail for a variety of problems. You can't specifically detect power failure. Also, most home phones get their power from the land line, which may or may not depend on local electric power and the phones that use mains power do so only to charge batteries. The whole idea of using a phone to detect power failure is extremely unreliable mainly because there is almost no correlation.
    – jay613
    Nov 30, 2021 at 15:15
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    I don't understand why power suppliers don't do this. They should have a phone number linked to each property and an automated process which sends out an SMS when the property loses power.
    – DWGKNZ
    Nov 30, 2021 at 16:02
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    @DWGKNZ because that would cost the PoCo money to implement and they wouldn't see a benefit from it, so they'd pass the cost on to you and you wouldn't be happy about it.
    – FreeMan
    Nov 30, 2021 at 18:01
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    I have a property which has an alarm fitted. Part of the deal is an automated call when power is out - followed by another when power is re-instated.Might be worth a call to various companies.
    – Tim
    Dec 1, 2021 at 8:53

8 Answers 8


There are all kinds of complex systems that can be set up to handle this. The key question is connectivity.

Landline + Answering Machine

This is probably the simplest and cheapest way, provided you already have a landline in that building. You do have to make sure that any phone company voice mail is off so that if the answering machine is not able to answer you get ringing instead of voice mail that is (essentially) a virtual answering machine. If the answering machine does not answer then one or more of the following have happened:

  • Power is out
  • Answering machine is full - not likely if the phone number is not used for regular business, plus many answering machines can be set to answer with a "Machine is full" message
  • Phone line is out

Fortunately, generally speaking, phone lines are more reliable than electricity. The odds of "phone line dead" without "power out" is relatively low.

* Note that a newer phone line that uses fiber (e.g., Verizon FIOS) will work just fine here. If the power goes out and kills the phone line as well as the answering machine, the effect (desired) of "ring but no answer" will be the same.

Internet Based - Heartbeat

If you already have an internet connection then this is also relatively easy. You need a computer - which could be anything from a Raspberry Pi to a full PC - and you program it to send a heartbeat message every hour. That can be an email or update a web site or many other things. If you don't see the heartbeat then:

  • Power is out
  • Computer is dead
  • Internet is out

How effective this will be depends on internet connection reliability.

Internet Based - Remote Check-in

Again, an internet connection is required. Instead of programming a computer to notify you, you check in on the computer. This could be:

  • Internet Camera - This has the advantage that you can use this for additional security purposes, if needed.
  • Web Server - Program a computer to act as a web server and check the web site. Gets a little complicated as you may have to deal with dynamic IP addresses, firewall settings, etc.
  • Router Access - If your router lets you do remote administration then this is a zero-cost (beyond the internet connection and router) solution as you don't have to actually connect any camera or computer or other device.
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    There used to be (probably still are, but Radio Shack died so the default place to get them is gone) land-line devices you could call and get a temperature check or various other data from. And you can get the same sort of functionality with an Arduino or RasPi via internet or data cell and appropriate sensors if you want to play with it - even keep track of the temperatures in the fridge and freezer.
    – Ecnerwal
    Nov 30, 2021 at 15:23
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    A Raspberry Pi strapped on to the back of the router, with a script running on startup, would be a nice solution if there is a router
    – Chris H
    Dec 1, 2021 at 10:10
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    Many answering machines can be set to "announce only" so they don't actually record anything. Then they don't fill up with robo-calls.
    – JPhi1618
    Dec 1, 2021 at 15:18
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    @manassehkatz-Moving2Codidact you're right of course, but an lot of people here are geeks who would just need a few pointers when it comes to the hardware. I hadn't looked but the OP would appear to have enough background for a code-based solution. Anyway you already had my +1; each of your suggestions would have been worthy of a vote, let alone the collection
    – Chris H
    Dec 1, 2021 at 15:30
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    @manassehkatz-Moving2Codidact I think DIY.se is one of the least geeky communities in the network, considering some of the questions at Cooking or English (I'm active across a broad selection of sites - and also work at the intersection of software, hardware, other equipment, and users)
    – Chris H
    Dec 1, 2021 at 15:37

maybe I could have a landline phone plugged in, and then I could call the number everyday to see if that rings.

A landline phone will ring (from the callers perspective) regardless of if it's even connected to the building, and will work if it is connected to the building but power is out (landline phones have their own power.) And unless paying for a landline is a given, they are "not inexpensive" to have. Low-end (particularly data-only, usually) cell service costs less, if cell service is available to the location. You could add a line-powered answering machine or computer attached to a modem (how antique!) and see if that picks up, or not.

There are a number of options, variously "creative" but likely the most straightforward (and "broader than just power out") would be a bog-standard security/fire alarm system, which will raise an alert when power is cut, and has other potential benefits given:

because I am usually not present at the building.

One with cellular notification to a central monitoring service is typically on a par with, or slightly less than paying for a landline phone, last I looked, and may save some (or quite a bit of) money on insurance. You can also configure them to call or otherwise notify you, depending what utilities you normally have at the building (internet, landline, or give it a cell link if you don't have a landline and can get service there.) But you generally don't get much of an insurance savings unless it's centrally monitored.

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    The thing I like about this solution is that these systems are designed for robust and unattended monitoring of a site. What you want. The monthly fee for the cellular service is worth considering, versus smart sockets and such that don't have a monthly fee but don't have "robust and unattended" as a key design feature. If you pick the right system you can cheaply add sensors for flood, fire, and obviously for burglary too. If the site does not already have internet service, a cellular-based alarm system is probably cheaper and simpler than adding internet and wifi to the site.
    – jay613
    Nov 30, 2021 at 15:28
  • Check that assumption about the land line having its own power. They used to. The only light in a blackout was from the phone button pad. But I found out that my landline no longer did - this about 10 years ago.
    – Willk
    Nov 30, 2021 at 20:16
  • @Willk it's possible the "landline" is connected via an ADSL router. I was offered a half-baked attempt at this a few years ago, but avoided it. There are now moves in the UK to move to purely digital telephone service, but at the moment landlines work if the home has no power. Not cordless ones of course; the base station/charger needs more power than the phone line can provide.
    – Chris H
    Dec 1, 2021 at 9:53

Landline phones usually are on their own power.

Think what you would need is a wifi power monitor that will phone/notify you when power goes out.

Something like this, first one I found, no recommendation of any.


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    An alternative to notifying you when the power goes out is to have a notification every hour. Failure to receive notification for 2 hours in a row indicates a high likelihood that the power is out. It could, of course, also just be an indication that WiFi/cellular/landline service is out, but it would be a flag to go check.
    – FreeMan
    Nov 30, 2021 at 14:59
  • @FreeMan Just wondering if after a few weeks of getting notify, that we would remember if they stopped.
    – crip659
    Nov 30, 2021 at 15:10
  • Assuming you have internet service, this is a good answer because the device does not require a smart home hub or anything else to support it. Here is a similar device that also monitors power consumption from the fridge so you can also be alerted if power remains but the fridge fails. This one doesn't send texts, it has a phone app that can be configure to notify various things.
    – jay613
    Nov 30, 2021 at 15:12
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    I get notifications from my on-site & off-site servers every 2 hours. The off-site backup is at a location with a wireless internet connection (my in-laws live in the middle of nowhere). I do, even after a couple of years, notice when one is missing. If I miss 2 or 3, I'll give them a call and ask if their internet connection is up. That's usually when they notice it's not... :D
    – FreeMan
    Nov 30, 2021 at 15:19
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    If the required WIFI is from a router/hub that is on the same power you are monitoring...this may not work. Nov 30, 2021 at 16:10

Many electric companies provide web meter reading.

So, you could check that the meter reading is increasing - some allow 30 minute updating while others can do 2 or 3 minutes.

You may find that the website for your account can send you data (or you scrape...) at specific intervals. Fridges not opened can survive for a couple of hours which gives you a window of time to work with.

  • Or the Electric Company website can message you (and up to 3-4 other people) when the power goes out - I believe my electric company has that option, AaMoF.
    – Ecnerwal
    Nov 30, 2021 at 15:28
  • Just checked - mine will email or text-message up to 4 contacts for an outage. Cost = nothing extra. Not bad.
    – Ecnerwal
    Nov 30, 2021 at 19:19

A cheap/old android mobile phone can be set up using some tasking software like macrodroid to send a message (email, sms) upon connect/disconnect of a charger.

I fairly confident that when you leave it plugged in, a powerloss will also trigger that event.

Depending on where you are this could be fairly cheap when using a pre-paid sim card.


Here's a cell-phone based suggestion, using an old Android phone, plugged in to a charger, and with a SIM card.

Use the app Tasker with the MyPower plugin which can detect if the phone is charging. Then use a Tasker action to send you an SMS if the power goes out.

In a little more detail, Tasker would run a timing loop to test the power status every minute (for example). The SMS text could be crafted to tell you when the power went off, and another SMS could tell you when it went back on. I'd also set it up to send me a daily "system OK" message.

If you prefer email, that's also possible, but requires a data plan or WiFi; if you've got WiFi avilable, you wouldn't need a SIM card, but the "OK" message would need to be more frequent as the WiFi will go down with the power so the lack of a message becomes the message.

Tasker can talk to apps like FolderSync, which can do FTP, but I've never made that work reliably; if you could get that working it could FTP a simple html file to a webserver under your control either via the phone network or WiFi, then you could query that file at your convenience.


You might have all the necessary kit already to allow you to use a "website monitoring" service, normally intended for businesses to keep an eye on their infrastructure, to check whether your "website" is up. All you need to do is make a "website":

  • If your ISP gives you a static IP address, skip the next point. Static IPs are rare because we're short on availability of them, but some people do have them
  • If your internet router supports a dynamic DNS service, enable it.
    • This will allow you to pick a fixed hostname, something like BFaleysHouse.DynDns.org and your router will update the hostname's IP address if the IP changes.

Then you need to make something the montioring service can reach and check if it's running:

  • Configure your router to respond to pings, or
  • Enable access to its admin interface from the internet and set a strong password, or
  • Find/create another device inside your home network that has some network service on it like an ftp server or web server and create a port forwarding from your router to that device
    • This is easier than it sounds; you might even have a smart fridge that has a mini web serve already! Loads of devices have some kind of network accessible control panel website, including printers, scanners, even TVs; all you want is something that will respond in some way (and the website built into the router for admin is ideal)

Finally, use a service like UptimeRobot that will email you whenever it sees your "website" (i.e. your router, or other internal device you;ve forwarded to) stop responding to pings/not give a response to the monitoring company's checks

UptimeRobot and similar services can "ping" the hostname you give; if you've enabled ping responding on your router (and your ISP doesn't block it) then it's a really quick and easy way to check if the router is on. If you havent got the option to enable ping and have instead arranged for a website to run on your router, or inside your network and the router forwards conenctions to the inside, then you tell UptimeRobot the address of the website, and perhaps a keyword to expect when it checks. This means there could be 3 kinds of response to a check:

  • The website responds with the usual page (welcome page, whatever) and it does contain the check-word: all is good
  • The website responds with an error or some other page that doesn't contain the check-word: you're probably still good
  • The website doesn't respond at all: you're either looking at a power cut, or a failure of the ISP network somewhere, so you might need to check on the fridge, call a neighbor etc

As you might detect; it's not foolproof - more can go wrong than just a powercut, that clobbers your monitoring but if your ISP is reliable then it's a reasonable bet that your power is out. If it's vital, I'd certainly recommend to combine it with another method of checking - that could be as simple as a dumb cellphone powered off an ac adaptor rather than a battery. No power, no phone on, can't call it..

..but the main thing about using these uptime monitoring services is that it's all automatic, nothing you need to do other than wait for them to email/SMS you

I have no affiliation with UptimeRobot


That might be related to the intruder alarm you have (my guess is you have one if you are mostly away as you stated). Many of the modern one have the ability to call or text or send an email to pre-defined number. Decent CCTV recorders also have an input other than their camera's signals. But I do not think your CCTV system is powered up with any UPS. What I think and it is a must is an changeover relay married to your distribution board and dropping contacts on power loss. Then 2-wire it to, depending on your intruder/cctv config, one of your security devices. Fail safe config will provide clear status (C and N/C, common and normaly closed). In case of loosing power it drops the contacts making a circuit C-N/C and because alarm systems are in fact battery powered it triggers it to send you an alarm.

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    I think there's some useful info here, but it's buried in the confusion. You start out addressing an intruder alarm, which the OP said nothing about, then mention CCTV, which could (as noted in other answers) could be used as a solution, but you don't explain how. Then you add "Then 2-wire it to..." and I'm not sure what you're referring to there at all. Please reread your Answer pretending you don't have a clue what you're talking about then edit it to fill in all the missing details. As noted, I'm sure you're on to something here, it just needs some clarity.
    – FreeMan
    Dec 1, 2021 at 12:22

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