A device that adds power to an Ethernet cable for Power over Ethernet (PoE) equipment. Although Ethernet switches are available with PoE capability, millions of regular "non-PoE" switches are in use and continue to be installed. A PoE injector is also called a "PoE adapter." See PoE
The injector plugs into an electric outlet and adds power to the Ethernet cable. In this example (bottom), the injector enables a PoE access point to be installed on the ceiling of a home without requiring a separate power cable.