Power over Ethernet (PoE) is a technology that allows devices to share power with each other. This can be useful for devices that need more power than the network can provide, or for devices that need to be connected through a single cable. PoE is also useful for connecting devices that are not compatible with traditional power supplies.
What Is Power over Ethernet?
Power over Ethernet, or PoE for short, is a method of providing both power and networking to a device via network cabling. Just like with wireless networking, there are different standards for various PoE implementations, with newer standards providing more power for more demanding devices.
Power over Ethernet is perfect for powering low-to-medium power devices like cameras, wireless access points, intercom systems, and keyless entry devices that can make use of both power and connectivity in a single cable.
The earliest standard was 802.3af, which provided 15.4 watts of DC power over standard Cat 3 and Cat 5 network cabling. This was followed up with the 802.3at standard, also known as PoE+, which expanded available power to 25.5 watts total.
While both of these standards are still used (and sold) today, 802.3bt, or PoE++, can now deliver up to 51 watts DC (Type 3) or 71.4 watts DC (Type 4) to power a far wider range of devices using Cat 5 or better cabling. This standard also provides support for 10 gigabit wired networking.
Power over Ethernet uses standard RJ45 network connections to deliver both power and networking to the same device.
Is PoE Different from Powerline Ethernet?
PoE is entirely different from Powerline Ethernet. While PoE uses network cabling and standard network connections to deliver power, Powerline Ethernet works somewhat in reverse, delivering networking over existing powerlines instead.
Powerline Ethernet allows you to lay down a wired network without having to put Ethernet cabling in the walls. PoE allows you to power lightweight devices using only the network cabling that you have available already.
While PoE will likely provide faster network speeds than powerline Ethernet, it doesn’t deliver anywhere near as much power.
Is Power over Ethernet Safe?
Running a small amount of power through your network cabling is surprisingly safe. Since PoE has been standardized, protections for the overloading and underpowering of devices have been built into standards since the early days of 802.3af.
PoE injects power into network cables between 44 and 57 volts DC for older standards, and between 50 and 57 for newer ones. This is regarded as a low voltage circuit, with 120 volts of DC power being considered the “safe limit” for direct contact.
There’s no need for special knowledge of electronics or an electrical certification to work with PoE. You can lay your own network cable, inject power into it, and run devices like cameras and access points without getting an electrician involved.
PoE allows devices to sip as much power as they want. A camera that needs 3 watts of power is only going to use 3 watts. A more pressing issue is that the power demands of your PoE endpoints don’t exceed the total available power on the network.
Why Choose Power over Ethernet?
Power over Ethernet is incredibly convenient. It uses the same basic Cat 5 and Cat 6 cabling that could already be in your walls. This allows you to power PoE devices anywhere you already have an Ethernet cable, provided that you remain within the power limitations of the network.
As long as your device can be powered over Ethernet, PoE could save you a lot of money. You can avoid the costs associated with hiring an electrician and a plasterer to lay fresh powerlines in your wall, with no painting and decorating to do afterward.
You also have way more flexibility in terms of where you put your access points, cameras, or whatever it is you’re powering. Laying an Ethernet cable can be done by virtually anyone, and the task doesn’t require any electrical knowledge or a certification.
PoE is also scalable, allowing you to grow with your network. Once the cables have been laid, you can upgrade your PoE switch or injector if you need more power. Expanding the network is a case of laying more network cable, which anyone can do.
Provided that you have overhead on the network, you can add more devices at a later date to expand your CCTV or wireless coverage.
What Do You Need for a PoE Network?
All you need for a PoE network is Ethernet cabling and a PoE injector. If you’re thinking of going this route, you probably already have network cabling throughout your house or workplace. If you don’t, any old Cat 5 or Cat 6 will do.
For small-scale PoE operations, like one conducted on a home network, you might want to stick to a relatively cheap PoE injector adaptor, also known as a midspan. These devices take power from the mains and inject it into your regular network.
You can get a relatively cheap PoE injector like the Cudy POE300 that supports older 802.3af/at standards for under $50. If you want the higher power output for 802.3bt, then you’ll need to spend closer to $100 for something like the Pocet Industrial PoE Injector.
For a more sophisticated setup that can handle a greater number of devices, a PoE-compliant network switch is the better option. A cheap 8-port 802.3af/at switch with 4 PoE ports like the TP-Link SG108PE will set you back around $60, while a 4-port switch with 802.3bt support like the IPCamPower PoE Network Switch comes in at just under $100.
If you’re going for a whole house worth of cameras, get a switch that’s rated for the total number of devices or total power draw of your network. If you just need to get a camera or access point into a difficult-to-reach location with no readily available mains power, consider a midspan.
One of the best things about PoE is that it’s scalable. Once the cable has been laid, you can upgrade your midspan or switch to add more power when you need it. Once you have the cabling and hardware, the next step is to add some PoE devices to your network.
What Devices Can You Power with PoE?
Many devices can benefit from the combined convenience of connectivity and power in a single cable. VoIP phones are one of the main devices that predicated this technology, allowing for handsets to draw a small amount of power from network hardware for basic telephony services.
Wireless access points like the tiny Ubiquiti AC LITE are also ideal candidates, as are CCTV cameras like the Amcrest UltraHD PoE Camera. With higher-powered 802.3bt networks, more sophisticated cameras (like those with active heating and cooling for harsh climates) and higher-capacity wireless access points can be powered by the network.
Many wireless ISPs use 4G and 5G modems to provide internet access to homes, and these devices are often roof-mounted for best reception. The use of low-voltage PoE can make the installation of such devices much easier and cheaper.
Public intercom systems like those found in apartment blocks could also use PoE more in the future since the network can provide enough juice to power the small webcams and microphones that these circuits rely upon.
Other devices that might benefit from a PoE network include IPTV decoders (like those found in hotels), connected lighting, wall clocks, keyless entry devices and keypads, automotive and industrial control systems, and point-of-sale kiosks.
You can also use PoE splitters like the $15 UCTRONICS PoE USB-C adapter to extract power from a network—for example, a 5-volt USB socket or wireless charging point for smartphones and similar devices. Even if it isn’t PoE-compliant, you might be able to power a USB device purely over Ethernet with the right equipment.
Is PoE Perfect for Everyone?
Power over Ethernet certainly has its place, but it’s not a magic bullet. It’s most useful if you live or work in a building that already has Ethernet cabling in the walls.
If you’d rather work in reverse and add Ethernet to your existing power cables, you should learn more about how using powerline Ethernet can solve your network problems.
