This chapter describes a model used to simulate lightning current. Comparison of different approaches used for lighting simulation has been mentioned. Transmission line approach has been chosen to simulate the grounding system behavior under lightning condition. Two different types of the grounding system have been studied under lightning conditions vertical driven electrodes and buried grids. This chapter draws attention also to the following points: equivalent circuit of a vertical ground rod on lightning condition, sensitivity analysis of soil parameters and grounding rod dimensions, equivalent circuit of grounding grid on lightning conditions and sensitivity analysis of soil parameters and grounding grid dimensions.
