Method for determining the operational status of a switching device for switching an electrical unit comprising a first circuit connected to a first phase of an electrical network and a second circuit connected to a second phase of the electrical network, each circuit (1, 2) respectively comprising: - a vacuum breaker (4, 4') placed in series in the circuit, the vacuum breaker (4, 4') comprising a fixed electrode (5, 5') and a mobile electrode (6, 6') able to move between a position (P1, P1') of maximum opening and a closed position (P2, P2'), - a control device (7, 7') kinematically connected to the mobile electrode (6, 6') via an elastic return device (8, 8'), wherein each circuit (1,2) comprises a position measuring device (11, 11') configured to measure a relative distance (D-r) between the control device (7, 7') and the mobile electrode (6, 6'), the method being characterized by the steps: - for each of the first and second circuits, when the control device (7, 7') causes the mobile electrode (6, 6') to pass from the position (P1, P1') of maximum opening to the closed position (P2, P2'), determining, from the measurements of the relative distance (D-r) between the control device (7, 7') and the mobile electrode (6, 6') a first transition instant (t1, t1') at which the mobile electrode (6, 6') comes into contact with the fixed electrode (5, 5'), - determining a difference (Delta1) between the first transition instant of the first vacuum breaker and the first transition instant (t1') of the second vacuum breaker, - determining that the operational status is a first status known as "nominal synchronization" if the difference (Delta1) is less than or equal to a first determined threshold, - determining that the operational status is a second status known as "abnormal synchronization" if the difference is greater than the first predetermined threshold. - a vacuum breaker (4, 4') placed in series in the circuit, the vacuum breaker (4, 4') comprising a fixed electrode (5, 5') and a mobile electrode (6, 6') able to move between a position (P1, P1') of maximum opening and a closed position (P2, P2'), - a control device (7, 7') kinematically connected to the mobile electrode (6, 6') via an elastic return device (8, 8'), wherein each circuit (1,2) comprises a position measuring device (11, 11') configured to measure a relative distance (D-r) between the control device (7, 7') and the mobile electrode (6, 6'), the method being characterized by the steps: - for each of the first and second circuits, when the control device (7, 7') causes the mobile electrode (6, 6') to pass from the position (P1, P1') of maximum opening to the closed position (P2, P2'), determining, from the measurements of the relative distance (D-r) between the control device (7, 7') and the mobile electrode (6, 6') a first transition instant (t1, t1') at which the mobile electrode (6, 6') comes into contact with the fixed electrode (5, 5'), - determining a difference (Delta1) between the first transition instant of the first vacuum breaker and the first transition instant (t1') of the second vacuum breaker, - determining that the operational status is a first status known as "nominal synchronization" if the difference (Delta1) is less than or equal to a first determined threshold, - determining that the operational status is a second status known as "abnormal synchronization" if the difference is greater than the first predetermined threshold. - for each of the first and second circuits, when the control device (7, 7') causes the mobile electrode (6, 6') to pass from the position (P1, P1') of maximum opening to the closed position (P2, P2'), determining, from the measurements of the relative distance (D-r) between the control device (7, 7') and the mobile electrode (6, 6') a first transition instant (t1, t1') at which the mobile electrode (6, 6') comes into contact with the fixed electrode (5, 5'), - determining a difference (Delta1) between the first transition instant of the first vacuum breaker and the first transition instant (t1') of the second vacuum breaker, - determining that the operational status is a first status known as "nominal synchronization" if the difference (Delta1) is less than or equal to a first determined threshold, - determining that the operational status is a second status known as "abnormal synchronization" if the difference is greater than the first predetermined threshold.