A Powered
Single Pair Ethernet (SPE) switch (1s) comprises first and second
trunk cable interfaces (P1, N1, P2, N2), at least one pair of inductors (5, 29, 7, 27) connected in series with one another between the
trunk cable interfaces, an internal power supply (18) for powering the SPE switch, a switching circuit (SC) connected to the internal power supply and the
trunk cable interfaces, a respective
voltage and / or current measurement circuit (8, 14, 11, 22, 23, 26) for each trunk cable interface, and a
decision circuit (9, 10, 16, 24, 25) configured to
signal whether one of the trunk cable interfaces has been shorted based on the
voltage and / or current measurement circuits. The switching circuit (SC) supplies power to the internal power supply (18) and has a first state allowing bidirectional flow of current between the first and second trunk cable interfaces, and a second state interrupting flow of current between the first and second trunk cable interfaces when the
decision circuit signals a
short circuit.