Power over Ethernet

Powered Ethernet allows electronics to be powered via the Cat5e cable. This is a huge plus for Ethernet installations as there is no need to install a separate power cable.


The standards for Powered Ethernet are:

  • IEEE 802.3af-2003
  • IEEE 802.3at-2009
  • IEEE 802.3bt (upcoming)

Powered Ethernet is usually abbreviated to PoE, meaning ‘Power over Ethernet’. The original PoE standard (IEEE802.3af-2003) provided a total maximum power of 15.4W per device (actually only guaranteed at 12.95W once cable volt drop is allowed for). The more recent IEEE802.3at-2009 version provides 25.5W and is generally called ‘PoE+’ or ‘PoE Plus’.

The upcoming IEEE 802.3bt standard (PoE++) promises significantly higher powers that would transform the lighting industry, as LEDs could be powered by the technology.

A PoE+ Ethernet switch is guaranteed to power a PoE device. However as a PoE Ethernet switch has a lower power rating it may not be able to power all PoE+ devices.

The development was originally driven by IP phones – for obvious reasons, IP phone manufacturers do not want to supply a separate power supply for every phone. Happily, the Entertainment Technology industry is riding the back of this technology wave.