Power over Ethernet carries both data and electrical power over a network cable. It lets a camera run from a switch instead of a local power outlet, which simplifies installation and lets the camera be rebooted remotely. The switch’s power budget and the camera’s requirement must match.
PoE is one of the reasons IP cameras are easier to install than older analogue systems. A single cable to the camera carries the video and the power, and the switch can restart a camera without anyone visiting the roof.
PoE and PoE+
Standard PoE provides a limited power budget per port. PoE+ provides more, which matters for PTZ cameras, heaters and devices with larger motors. A switch may also have a total power budget that is lower than the sum of its ports.
- Check the camera’s power requirement, not just its voltage.
- Check the switch’s per-port and total power budget.
- Allow headroom for heaters and PTZ motors.
Cable and distance
PoE runs over the same copper cable as the network data, and the usual distance limit applies. Longer runs need a midspan injector, a switch closer to the camera, or fiber with a local power source.
Why it matters for reliability
A camera on a local power adapter loses its connection when the adapter fails. A PoE camera can be power-cycled from the switch, and the switch can be put on a UPS with the recorder.