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PoE Plus moving forward

Feb 21, 20062 mins

* Enhanced Power-over-Ethernet moves closer to standard

A year ago I highlighted the efforts of the IEEE to increase the electrical power available to devices over Ethernet. At that point the effort was only at the “study group” level. Since then the standards effort has gathered more momentum.

Last September the Power-over-Ethernet (PoE) Plus effort graduated to a task force with the designation 802.3at. Its objective is to enhance the standard set by 802.3af, which in 2003 had limited the power that could be delivered along with Ethernet signals to about 15 watts.

That was enough to support IP phones, wireless LAN access points and other network-based equipment, but there are other applications to consider, such as video phones, biometric access controls and point-of-sale devices.

More recently, Network World ran a Tech Update story written by two of the members of the task force. The article says that the task force is still weighing whether to put electrical current on two wire pairs or on all four pairs within the Ethernet cable: “Each copper wire in a cable’s bundle can take only so much power before being damaged. Likewise, the wires in an Ethernet bundle can carry only so much total wattage before the bundle overheats, creating cable life-expectancy concerns.”

Yikes. No, we don’t want to melt the Ethernet cables.

Even with those concerns, however, the group is looking at pushing PoE Plus to 30 watts, and even as high as 60 watts, which opens up a whole range of devices that could be enabled with the technology.