Power over Ethernet (PoE) is a means of carrying electrical power through data cables. With PoE enabled devices, electrical current passes through the ethernet cable along with the data normally carried by an ethernet cable.
The main advantage of PoE is that it reduces the cabling requirements for network devices. Any device which normally connects to an internet or LAN network with an ethernet cable will also need a power cable – one to carry the data, one to carry the electrical current to power the device.
With a PoE connection, there is no need for the additional power cable. The ethernet also carries the electrical current.
How does PoE work?
Ethernet cables are generally made with spare data carrying capacity. Most cables contain four pairs of wires, but usually only use two of these pairs – the exception is Gigabit cable, which makes use of all four pairs of wire to deliver greater, faster data carrying capacity.
PoE utilises the spare wiring capacity in most ethernet cables. The two pairs of wires not being used for data are adopted as conductors to create a power circuit. Any ethernet cable at Category 5 or above is safe to carry current, and because separate bundles of wire are being use to carry the data and the power, there is no risk of interference between the two.
As well as a suitable ethernet cable, PoE requires a device capable of being powered by PoE, and either a specialised PoE router or an ordinary router with an intermediary power switch.
The benefits of PoE
Any device which connects to a network via an ethernet cable – VoIP telephones, wireless routers, IP security cameras – needs only one cable connection to power and operate if you use PoE. This makes installation simpler and less expensive, which helps when it comes to scaling up networks by adding new connections and devices.
PoE connections also offer greater flexibility in terms of where you can locate a device, as you are not dependent on mains plug sockets or other power sources. This also offers benefits in terms of reliability and safety – power comes from a single, stable source, rather than a variety of different adapters in different sockets. There is therefore less risk of power outages, overload and potential damage to equipment.
