Abstract: Telecommunications are conveyed between sub-stations of a high-voltage electricity distribution network by high-frequency carriers using the power lines as transmission media. The filtering device attenuates high frequencies spilling over from one line section to the next. Filter elements in series with the line are high-voltage units passing high currents and are therefore expensive. Coarse-tuned high-voltage filter elements include an HF drain path to earth. Fine-tuned low-voltage filter elements at the earth end of the Hf drain path prevent wanted signals from being lost.