PoE Standards Explained: 802.3af, 802.3at and 802.3bt

Understand common PoE standards, power classes and what they mean when selecting CCTV switches and powered devices.

802.3af

The original widely deployed PoE standard is intended for lower-power devices and is common with many basic IP cameras and network endpoints.

802.3at

PoE+ provides more available power and is useful for higher-power cameras and devices that exceed basic PoE requirements.

802.3bt

Higher-power PoE generations use additional pairs and provide substantially more power for suitable devices. Exact delivered power depends on the class and equipment.

What to check on a CCTV project

Match the camera's required input power and PoE standard with the switch port capability and total switch budget. Also verify the actual model specification rather than relying only on a generic label.

Common mistake

A switch being labeled 'PoE' does not mean every port can supply every camera at maximum power. Check both per-port capability and the overall power budget.