PoE (Power over Ethernet) is a method of delivering electrical power to a network device along the same cable that carries its data. A PoE switch or injector supplies power onto the cable; a PoE-capable device draws power from it. This removes the need for a separate power supply at the device, which simplifies installation and is particularly valuable for ceiling-mounted cameras, outdoor access points, and IoT devices in hard-to-power locations.

In short: PoE is governed by IEEE standards. 802.3af (the original PoE) delivers up to 15.4 W. 802.3at (PoE+) delivers up to 30 W. 802.3bt (PoE++ or 4PPoE) delivers up to 60 W (Type 3) or 100 W (Type 4). Devices negotiate their required power level with the switch during link-up, so a switch can mix devices of different PoE classes on different ports without manual configuration.

For IoT and security deployments, PoE substantially reduces installation cost. A single Cat 5e or Cat 6 cable to a CCTV camera carries both video and power, eliminating the need for a local electrician to run mains to each camera position. The same applies to outdoor Wi-Fi access points and many industrial sensors.

Some industrial routers support PoE input, allowing them to be powered from a PoE switch rather than a separate DC supply. The Proroute H685F-W-POE is an example. This is particularly useful in CCTV deployments where PoE infrastructure is already in place. Other routers offer PoE output on selected ports, so a router with cellular WAN can power downstream cameras or access points without additional hardware.