A power over Ethernet device is provided. The power over Ethernet device includes a first Ethernet connector, an Ethernet transformer circuit, and a detection circuit. The first Ethernet connector is coupled to a second Ethernet connector of a network device via an Ethernet cable and has a first reserve pin and a second reserve pin. The Ethernet transformer circuit is coupled to the first Ethernet connector to provide a supply voltage to the Ethernet cable to transfer the supply voltage to the network device. The detection circuit receives the supply voltage and is coupled to the Ethernet transformer circuit, the first reserve pin, and the second reserve pin to provide a reference voltage to the first reserve pin and receives an identification voltage from the second reserve pin to determine whether the network device is a powered device.