Power over Ethernet (PoE) is the delivery of DC power along with data over short distances of Ethernet unshielded, twisted-pair cables and has evolved from proprietary solutions to inclusion in the IEEE802.3af standard of 2003, and again in IEEE802.3at of 2009 for PoE+. Ethernet data transmission requires two of the four available pairs in standard Cat5e/6 cabling. PoE can deliver power either over the remaining two spare pairs, over the data transmission lines by using signal transformers, or via both methods together for maximum wattage (PoE+). Via PoE, DC power is delivered to devices that are located near Ethernet cables, but where additional standard AC lines are either not possible or not convenient.

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