A Power over Ethernet "PoE" system comprising: Power Sourcing Equipment "PSE" selectably connectable to a set of data wire pairs (12, 13) and to a set of spare wire pairs (14, 15) in an Ethernet system for providing a PoE voltage over at least the data wire pairs; a Powered Device "PD" connected to the PSE by at least the data wire pairs to receive the PoE voltage; and a PSE controller as part of the PSE, the PSE controller comprising: a first output port; a second output port; a first switch control port (GATE1) coupled to a first switch, the first switch selectively coupling the PoE voltage to the data wire pairs; a second switch control port (GATE2) coupled to a second switch, the second switch selectively coupling the first output port to the second output port; and processing circuitry configured for performing the method comprising: keeping the first switch and the second switch off during a detection and classification routine, performed via the first output port and the second output port; performing the detection and classification routine to determine if the PoE voltage should be applied to both the data wire pairs (12, 13) and the spare wire pairs (14, 15), or to only the data wire pairs, or to neither the data wires pairs or the spare pairs; keeping the second switch off while turning on the first switch to supply the PoE voltage to only the data wire pairs (12,13) if it is determined that the PoE voltage should only be provided to the data wire pairs (12, 13); and Power Sourcing Equipment "PSE" selectably connectable to a set of data wire pairs (12, 13) and to a set of spare wire pairs (14, 15) in an Ethernet system for providing a PoE voltage over at least the data wire pairs; a Powered Device "PD" connected to the PSE by at least the data wire pairs to receive the PoE voltage; and a PSE controller as part of the PSE, the PSE controller comprising: a first output port; a second output port; a first switch control port (GATE1) coupled to a first switch, the first switch selectively coupling the PoE voltage to the data wire pairs; a second switch control port (GATE2) coupled to a second switch, the second switch selectively coupling the first output port to the second output port; and processing circuitry configured for performing the method comprising: keeping the first switch and the second switch off during a detection and classification routine, performed via the first output port and the second output port; performing the detection and classification routine to determine if the PoE voltage should be applied to both the data wire pairs (12, 13) and the spare wire pairs (14, 15), or to only the data wire pairs, or to neither the data wires pairs or the spare pairs; keeping the second switch off while turning on the first switch to supply the PoE voltage to only the data wire pairs (12,13) if it is determined that the PoE voltage should only be provided to the data wire pairs (12, 13); and a first output port; a second output port; a first switch control port (GATE1) coupled to a first switch, the first switch selectively coupling the PoE voltage to the data wire pairs; a second switch control port (GATE2) coupled to a second switch, the second switch selectively coupling the first output port to the second output port; and processing circuitry configured for performing the method comprising: keeping the first switch and the second switch off during a detection and classification routine, performed via the first output port and the second output port; performing the detection and classification routine to determine if the PoE voltage should be applied to both the data wire pairs (12, 13) and the spare wire pairs (14, 15), or to only the data wire pairs, or to neither the data wires pairs or the spare pairs; keeping the second switch off while turning on the first switch to supply the PoE voltage to only the data wire pairs (12,13) if it is determined that the PoE voltage should only be provided to the data wire pairs (12, 13); and keeping the first switch and the second switch off during a detection and classification routine, performed via the first output port and the second output port; performing the detection and classification routine to determine if the PoE voltage should be applied to both the data wire pairs (12, 13) and the spare wire pairs (14, 15), or to only the data wire pairs, or to neither the data wires pairs or the spare pairs; keeping the second switch off while turning on the first switch to supply the PoE voltage to only the data wire pairs (12,13) if it is determined that the PoE voltage should only be provided to the data wire pairs (12, 13); and