The qualitative electric supply has become a critical element of the civilized world. The continuous supply of the power system is highly dependent on the construction of the electrical network, so it is essential that we take the maximum care during the planning of this system. My thesis mainly deals with the theme of operating safety, especially with the design of the grounding systems. A well-planned grounding system can eventually save human lifes, so simulating it is a quite important step of the testing before the final construction. With the simulations we can discover the defects of the planning, and correct them before it is to late. I describe in details how the elements relate to each other in the substation grounding systems and how they "behave" in the real life situations, and I make a grounding-grid examination in one particular case. The main tool of my work is a Canadian software package which gives me the opportunity to simulate and audit the ground potential rising of a real substation in the case of electrical faults.