PoE (Power over Ethernet)

PoE is defined by IEEE 802.3 standards; successive versions (802.3af, 802.3at and 802.3bt) raised the power a switch port can deliver, from enough for a phone to enough for a pan-tilt camera, a large access point or a video bar. The switch (or a midspan injector) supplies the power, the device negotiates how much it needs, and a single cable does both jobs.

For a growing business PoE is what makes phones, access points and cameras easy to place: wherever a cable can go, the device can go, and a battery backup on the switch keeps them running through a power cut. The catch is budget: every powered port draws from the switch's total, and a fully loaded switch with cameras and access points can exceed it.

Ask your network partner for the total PoE budget of each switch against the devices planned, which PoE standard each device needs, whether the cabling is certified for the power and distance, and whether the switches are on battery backup. Ask what happens when the budget is exceeded, because some switches simply stop powering the last device plugged in.