Power over Ethernet Technology

What is Power over Ethernet?

Power over Ethernet (PoE) is a technology that enables powered devices, such as a VoIP  phone, wireless access point, surveillance cameras, etc., to receive electrical power and data over the same Ethernet cable, supporting the same 100m transmission distance.

This eliminates the need for a separate alternating current (AC) electrical connection and power lines to supply power for the device. PoE minimizes the number of cables that must be strung in order to install a network device, resulting in reduced costs, less downtime, increased flexibility, and simplified maintenance.

PoE devices support 10/100/1000BaseT  communication speeds.

For PoE to work, electrical current enters the Ethernet data cable at the power-sourcing equipment (PSE), and exits at the powered device end (PD) in such a way that the power and data communications can coexist on the same cable.

Devices are classified into two different groups depending on which wires in the Ethernet cable are used to power the device. Mode A devices use pins 1, 2, 3, and 6 for data communications and those same pins to power the device.

Mode B devices separate the data and power by using pins 1, 2, 3, and 6 for data communication and pins 4, 5, 7, 8 to power the device.

Power-over-Ethernet network segments use Category 6 (Cat 6) or higher rated Ethernet cable, which consists of four twisted pairs of copper wire. Power-sourcing equipment such as a PoE enabled switch or PoE Injector utilizes a power supply and is network connected to a powered device.

The power-sourcing equipment detects the presence of a connected device, determines if the device is a powered device, and then passes electrical current into the Category 6 cable. The powered device functions solely from the power it receives through the Ethernet cable, bypassing the need for installation of separate electrical wiring and/or additional power supplies.