A method of diagnosing an operating state of a switching device, configured to be coupled to an electrical conductor and comprising: - separable contacts (24, 28) associated with the electrical conductor and controlled by an electromagnetic actuator comprising a coil connected to an electronic control device, which is configured to apply a control coil voltage (U BOB) across the coil terminals, - sensors (Rsh, 50) configured to measure a magnitude of a coil current (I BOB) flowing in the coil and the coil voltage (U BOB), wherein the method comprises the steps of: a) receiving an opening command from the switching device, the switching device initially being in an open state, the closing command being received by the electronic control device; b) after receiving the closing command, commanding the electromagnetic actuator to close by means of the electronic control device; c) while the switching device is switched to the closed state, measuring and recording the coil voltage (U BOB) and coil current (I BOB) values; d) calculating and recording values of a magnetic flow ( φ) passing through the coil, by integrating the recorded values of the coil current, the coil voltage and the resistance (R BOB) and inductance (L BOB) values of the coil, previously recorded in the electronic control device; characterised in that the method further comprises the step consisting of: (e) from the recorded of magnetic flow ( φ) and coil current (I BOB) values, evaluate and record positions ( x) of a core of the electromagnetic actuator as a function of a data table characteristic of the electromagnetic actuator, the data table being previously recorded in the electronic control device and defining a bijective relationship between the position ( x) of the core, the magnetic flow ( φ) and the coil current (I BOB). - separable contacts (24, 28) associated with the electrical conductor and controlled by an electromagnetic actuator comprising a coil connected to an electronic control device, which is configured to apply a control coil voltage (U BOB) across the coil terminals, - sensors (Rsh, 50) configured to measure a magnitude of a coil current (I BOB) flowing in the coil and the coil voltage (U BOB), wherein the method comprises the steps of: a) receiving an opening command from the switching device, the switching device initially being in an open state, the closing command being received by the electronic control device; b) after receiving the closing command, commanding the electromagnetic actuator to close by means of the electronic control device; c) while the switching device is switched to the closed state, measuring and recording the coil voltage (U BOB) and coil current (I BOB) values; d) calculating and recording values of a magnetic flow ( φ) passing through the coil, by integrating the recorded values of the coil current, the coil voltage and the resistance (R BOB) and inductance (L BOB) values of the coil, previously recorded in the electronic control device; a) receiving an opening command from the switching device, the switching device initially being in an open state, the closing command being received by the electronic control device; b) after receiving the closing command, commanding the electromagnetic actuator to close by means of the electronic control device; c) while the switching device is switched to the closed state, measuring and recording the coil voltage (U BOB) and coil current (I BOB) values; d) calculating and recording values of a magnetic flow ( φ) passing through the coil, by integrating the recorded values of the coil current, the coil voltage and the resistance (R BOB) and inductance (L BOB) values of the coil, previously recorded in the electronic control device; characterised in that the method further comprises the step consisting of: (e) from the recorded of magnetic flow ( φ) and coil current (I BOB) values, evaluate and record positions ( x) of a core of the electromagnetic actuator as a function of a data table characteristic of the electromagnetic actuator, the data table being previously recorded in the electronic control device and defining a bijective relationship between the position ( x) of the core, the magnetic flow ( φ) and the coil current (I BOB).