When applying shielded ECG leads to a patient, during the presence of strong RF signals such as electrocautery, high currents may flow through the cable capacitance to the shield and from there back to the patient via another cable capacitance and electrode, thus causing skin burnings. Such high currents can be reduced dramatically when the shields of the lead cable are separated by means of connecting series resistances into the shield conductors. Implementing these resistors into a ECG trunk cable allows the usage of uniform lead cables for all applications.