A current measuring device is protected against electrical surges in the event of the device being open circuit. The device includes a first current transformer, a first connection terminal having connected thereto a first terminal of the first current transformer, a second connection terminal having connected thereto a second terminal of the first current transformer, a protective resistance having a first terminal connected to the second connection terminal, and a load resistance connected between the first and second connection terminals across the terminals of which a voltage is measured from which the current flowing in a circuit passing through the first current transformer is determined. The device also includes a second current transformer connected to the terminals of the protective resistance, and current branch connection structure connected between the first connection terminal and a second terminal of the protective resistance.