@OP,
I see you live in Germany. Voltage is 230V I believe.
From what I have read Germany does not ground the electrical service like we do here in the U.S. Can you shed any light on how the electrical service is grounded in your area in Germany?
In the U.S. we connect, ground, the service entrance neutral conductor at a dwelling unit directly to Mother Earth. Example Ground Rods.
My understanding for Europe is the Utility Power Transformer’s neutral is connected to Mother Earth at the transformer only. Not again there after. At the dwelling unit there is a ground bar in the electrical panel that connects to a ground rod driven in the Earth. All safety equipment grounds connect to the ground bar. That is a stark difference in the two grounding systems. The only reference from the dwelling unit service entrance neutral conductor to the neutral, grounded, connected, to Earth at the utility Power Transformer is through the soil of the Earth. Potentially a high impedance path...
I can’t help but wonder how the shield of a shielded power cord used in Germany functions.
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