A method is disclosed for reducing the common mode current flowing between the internal ground of an electrical circuit in an automotive vehicle, and the earth, when electric power is exchanged between an electric power storage unit of the electrical circuit and an electric power source external to the circuit. An electronic component is used to apply an electrical quantity as a function of the common mode current to an injection point in the circuit in order to reduce the common mode current. The value of the common mode current is obtained using a measuring device having a magnetic torus configured to be traversed by an electric line by which the electric power is exchanged, the electric line forming a primary winding, a secondary winding, wound about said torus for generating a magnetic flux on the basis of a reference current, and an oscillator for generating the reference current through the secondary winding.