A method for diagnosing the wear status of an electrical switching unit including a phase for monitoring the electrical unit. The monitoring phase uses: learning data previously loaded and representative of the type of electrical unit, and initialization data corresponding to the unit to be monitored and stored in memory during an initialization phase. The monitoring phase includes the measurement and the acquisition of a measurement curve upon the opening of the electrical unit, the determination of values of local descriptors with little sensitivity to the temperature from the measurement curve as a function of values of the measurement curve, of initialization data, and of learning data, the determination of a global status class as a function of the positioning values. The device and the electrical unit implement the method.