Earth currents, often named as vagabonding currents, are not only a problem in industrial plants. Even in commercial enterprises and residential buildings these currents can create problems.

The picture on the right shows the cause of a disturbing whistling in the loudspeakers of a house stereo system. The diagram shows a distorted voltage because of leakage currents of a VSD motor which, due to their characteristics, must flow back to the transformer starpoint if a corresponding filter on the converter is missing or defective. This results in common-mode voltage distortions of the phase to ground voltages at the clock frequency of the converter output. The clock frequency currents were detectable on the earthing system of the entire building and also on the disturbed stereo system.

Solution was the replacement and EMC compatible installation of a suitable filter.