The paper describes some special characteristics of the growth of the ground potential and the potential shown in the figure at stations supplied from combined high-voltage cable-overhead lines. Analysis of the requirements for forming a complex grounding system that will include the grounding systems of all stations connected by high-voltage cables. The influence of modern high-voltage cables on the relative amount of current discharged into the ground is highlighted and analyzed. A procedure for determining reduced currents and potentials on a complex grounding system is presented. As an example, the results of calculations on a complex grounding system in a combined double cable-overhead high-voltage line are given.