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UPS power supply units

What if the Lights Go Out? A Guide to UPS Power Supply Units

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If you’re becoming reliant on more and more smart home devices, you might start to wonder how they will handle a power cut.

Computers, especially older ones, could take these things rather badly! And what if your security, your doorbell and even your locks are connected to the grid?

First things first – power cuts are not a new phenomenon, and they were are convenient before smart home technology came along.

A distinction needs to be drawn between the new features that smart tech provides, and the more serious worry that you won’t have access to even the basic functionality.

You certainly wouldn’t want a lock that wouldn’t open in the event of a fire, for example.


It’s very likely that, if the power goes, you will lose your connection to the internet as well.

That’s because, in the average home, your internet router is powered with mains electricity and so in the event of a power failure you’ll also get an internet failure.

So the real question is what will happen to your key devices in that event.


Security cameras like the Nest Cam Indoor or Outdoor simply stop working without power.

Battery-powered camera are no better if they depend on Wi-Fi to operate, but some – like the Reolink Argus 2 – can record to an SD card and are solar powered.


Door locks have to include batteries, so when the power goes their only loss is the Wi-Fi (and with it the internet). That means you’ll still be able to open the door with the RFID keys, or Bluetooth, but not via the app’s internet connection.

There will always be a physical turn on the inside too.


This goes without saying, but your smart bulbs will go out. The question is what happens when the power comes back on. In many cases, the lights will come on too, perhaps even if they were off.


Some doorbells are powered by a low voltage supply  that nevertheless comes from your mains power, so these would stop functioning.

Others are battery powered (Ring, for example, offers both), but still need their Wi-Fi connection to send you an alert to your phone.

The optional ringer devices typically are also outlet-powered, so, without the internet, you’d be left with a working doorbell camera that nevertheless couldn’t reach you.


Smoke detectors like the Nest Protect feature battery back-up (three lithium AA cells), so they will still perform their key alert functions.

Sadly without the network they cannot act as a chime for a doorbell, for example.


When power is restored, devices will need a few moments, but you will likely find this very straightforward.

Mercifully most devices store their settings in EPROM (Erasable Programmable Read-Only Memory) and their own software in firmware, so you won’t need to go through the set-up procedure again, just wait for things to boot up and then find their network connections.

You may well know this experience from rebooting your router and waiting for the Wi-Fi to appear on your computer.


Many businesses use an Uninterruptible Power System (UPS) to protect their key systems against a sudden power failure.

Despite the very confident name, these systems are really best used to provide a few minutes to allow a server to be shut down properly and prevent any damage to files, which are midway through being moved.

UPS power supply units work just like the battery does in a laptop – pull out the power cord and the power will start to be drawn from the battery until it runs out.

Since a Wi-Fi router and hub doesn’t have an especially strong draw, the actual internet connection comes down a different cable to your energy, you could use a UPS to provide a slightly longer period of protection for your internet connection.

For every additional device you connect to the UPS power supply unit, the shorter the back-up will last (a desktop computer would drain one of these in a matter of minutes).


Power: 1500VA/900W, 12 Outlets

Simply plugged into the mains, with your devices attached, this UPS power supply unit can provide energy for a desktop computer, also serving as a surge protector ensuring that your devices are protected from spikes in the power.

You can plug several into the kettle-style sockets and 12 US sockets (6 battery backup & surge protected outlets and 6 surge protected outlets) at the back, or the USB ones on the front.

1,500VA is enough energy to run a 240V desktop computer and monitor for around an hour or so, depending on the draw.