An apparatus comprising: a first electrical connector (306, 408) designed to be connectable to a first power source (101, 801, 1001); a second electrical connector (307, 403) designed to be connectable to a second power source (101, 801, 1001); a first electrical conductor (308, 409, 708) coupled to the first electrical connector; a second electrical conductor (309, 404, 709) coupled to the second electrical connector; a switching element coupled in series, via the first electrical conductor and the second electrical conductor, between the first electrical connector and the second electrical connector, wherein the switching element comprises a transistor comprising a source terminal (Vs) coupled to the first electrical conductor, a drain terminal (Vd) coupled to the second electrical conductor and a gate terminal (Vg); a controller (303, 503, 710) coupled to the gate terminal serving as a control terminal of the switching element, the controller configured to be responsive to an indication of a potentially unsafe condition and configured to: control the switching element to an ON state to connect the first electrical conductor to the second electrical conductor, and in response to an indication of a potentially unsafe condition, control the switching element to an OFF state to disconnect the first electrical conductor from the second electrical conductor; and an auxiliary power circuit (304, 504, 704, 702a, 704a) comprising a DC/DC converter, wherein a first input to the converter is coupled to the source terminal and a second input to the converter is coupled to the drain terminal, wherein the converter is configured to convert the drain-to-source voltage at its inputs to a larger voltage at its output for powering the controller. a first electrical connector (306, 408) designed to be connectable to a first power source (101, 801, 1001); a second electrical connector (307, 403) designed to be connectable to a second power source (101, 801, 1001); a first electrical conductor (308, 409, 708) coupled to the first electrical connector; a second electrical conductor (309, 404, 709) coupled to the second electrical connector; a switching element coupled in series, via the first electrical conductor and the second electrical conductor, between the first electrical connector and the second electrical connector, wherein the switching element comprises a transistor comprising a source terminal (Vs) coupled to the first electrical conductor, a drain terminal (Vd) coupled to the second electrical conductor and a gate terminal (Vg); a controller (303, 503, 710) coupled to the gate terminal serving as a control terminal of the switching element, the controller configured to be responsive to an indication of a potentially unsafe condition and configured to: control the switching element to an ON state to connect the first electrical conductor to the second electrical conductor, and in response to an indication of a potentially unsafe condition, control the switching element to an OFF state to disconnect the first electrical conductor from the second electrical conductor; and an auxiliary power circuit (304, 504, 704, 702a, 704a) comprising a DC/DC converter, wherein a first input to the converter is coupled to the source terminal and a second input to the converter is coupled to the drain terminal, wherein the converter is configured to convert the drain-to-source voltage at its inputs to a larger voltage at its output for powering the controller. control the switching element to an ON state to connect the first electrical conductor to the second electrical conductor, and in response to an indication of a potentially unsafe condition, control the switching element to an OFF state to disconnect the first electrical conductor from the second electrical conductor; and an auxiliary power circuit (304, 504, 704, 702a, 704a) comprising a DC/DC converter, wherein a first input to the converter is coupled to the source terminal and a second input to the converter is coupled to the drain terminal, wherein the converter is configured to convert the drain-to-source voltage at its inputs to a larger voltage at its output for powering the controller.