In this paper, the TS 110/20(10) kV Sucidar earthing system was modeled based on the available project documentation for the substation and the associated high and medium voltage connecting lines. The earthing system characteristics were calculated and the compliance with the prescribed safety conditions was verified. The earthing system calculation was performed using a special computer program for calculating the earthing system. The reduced current was defined, the method of its calculation was defined, and a specific amount was given for the substation in question based on data on short-circuit currents. The specific soil resistance obtained by measuring using the vertical electrical probing method, with the Schlumberger probe arrangement, was given. The input data of the earthing components were calculated, namely the impedances of the mesh earthing system, the earthing of HV and LV stations, screens and cable earthing systems. The earthing system potential was calculated using the EarthCAD computer program and a 3D representation of the potentials inside and outside the substation was created. By intersecting the 3D representation with planes perpendicular to the potential axis, equipotential lines were obtained. Finally, a verification of the safety conditions was performed.