A method for identifying a malfunctioning current sensor in an electrical apparatus, in which an electrical power supply of the electrical apparatus is at least partly supplied by a switched-mode electrical power supply circuit connected to at least one current sensor which samples an electrical current in a phase conductor of an electrical installation, the power supply circuit delivering a regulated electrical voltage, the method including: determining a switching duty cycle of a power switch of the switched-mode electrical power supply; analysing the determined switching duty cycle; and identifying a failure condition if the behaviour of the switching duty cycle is representative of a malfunctioning of at least one of the current sensors.