An electrical supply system including: a) a voltage converter including: i) a voltage converter input (110.1) electrically coupled to a supply (S) for receiving a supply signal; and, ii) a voltage converter output (110.2) for supplying an output signal, the output signal having an output voltage (Vo) different to a supply voltage (Vs) of the supply signal; b) a bus electrically coupled to at least one of a load ( L ) and a battery ( T ); c) a first voltage sensor for detecting the output voltage; d) a current sensor ; and e) an electronic processing device coupled to the sensors for detecting a fault in the electrical supply system ; characterised in that : the system further includes a diode including: a diode input (120.1) electrically coupled to the voltage converter output (110.2), and a diode output (120.2), wherein the bus electrically coupled to the diode output (120.2); wherein the current sensor detects a diode input current ( I DI ); and wherein the electronic processing device is configured such that it: selectively controls the voltage converter to change the output voltage ( V O ); monitors the resulting change in the diode input current ( I DI ) and the output voltage ( V O ); and, detects the fault in the electrical supply system based on at least the diode input current ( I DI ) change and the output voltage ( V O ). a) a voltage converter including: i) a voltage converter input (110.1) electrically coupled to a supply (S) for receiving a supply signal; and, ii) a voltage converter output (110.2) for supplying an output signal, the output signal having an output voltage (Vo) different to a supply voltage (Vs) of the supply signal; i) a voltage converter input (110.1) electrically coupled to a supply (S) for receiving a supply signal; and, ii) a voltage converter output (110.2) for supplying an output signal, the output signal having an output voltage (Vo) different to a supply voltage (Vs) of the supply signal; b) a bus electrically coupled to at least one of a load ( L ) and a battery ( T ); c) a first voltage sensor for detecting the output voltage; d) a current sensor ; and e) an electronic processing device coupled to the sensors for detecting a fault in the electrical supply system ; characterised in that : the system further includes a diode including: a diode input (120.1) electrically coupled to the voltage converter output (110.2), and a diode output (120.2), wherein the bus electrically coupled to the diode output (120.2); wherein the current sensor detects a diode input current ( I DI ); and wherein the electronic processing device is configured such that it: selectively controls the voltage converter to change the output voltage ( V O ); monitors the resulting change in the diode input current ( I DI ) and the output voltage ( V O ); and, detects the fault in the electrical supply system based on at least the diode input current ( I DI ) change and the output voltage ( V O ). characterised in that : the system further includes a diode including: a diode input (120.1) electrically coupled to the voltage converter output (110.2), and a diode output (120.2), wherein the bus electrically coupled to the diode output (120.2); wherein the current sensor detects a diode input current ( I DI ); and wherein the electronic processing device is configured such that it: selectively controls the voltage converter to change the output voltage ( V O ); monitors the resulting change in the diode input current ( I DI ) and the output voltage ( V O ); and, detects the fault in the electrical supply system based on at least the diode input current ( I DI ) change and the output voltage ( V O ). selectively controls the voltage converter to change the output voltage ( V O ); monitors the resulting change in the diode input current ( I DI ) and the output voltage ( V O ); and, detects the fault in the electrical supply system based on at least the diode input current ( I DI ) change and the output voltage ( V O ). <EOS>