The article presents an originally developed mathematical model intended for the calculation of the distribution of single-pole short-circuit currents in grounding systems with the presence of electromagnetic coupling between parallel-conducted lines. This mathematical model uses originally developed expressions to determine the parameters of the replacement circuit, which precisely replaces the system of passive conductors in the area of their parallel conduction between neighboring grounding devices in a very convenient way. Based on the aforementioned mathematical model, a program entitled RASTRUZ was created, which calculates the distribution of single-pole short-circuit currents in the grounding system of the selected double cable-overhead line and its incident network.