EMC filter, connectable between a supply network and an electric operated appliance to reduce conduction noise between said supply network and said appliance, comprising one voltage regulator having an output terminal whose potential is kept close to the earth potential, in order to reduce the voltage drop, at mains frequency, across a “Y” capacitor or an active shunt module. In this way the leakage current to earth is sensibly reduced. The device of the invention is especially useful in corner-earthed three-phase lines or in conjunction with RCD devices.