In this paper simplified approaches for the earth surface potentials and GPR of substation grounding are presented in case of uniform or non-uniform soil. The equalization of current density and then decreasing of GPR is achieved. The image method is suggested to calculate the GPR and the earth surface potentials with accurate results for the grids buried in uniform or non-uniform soil structure. The voltage profiles have been designed in 3D to make the selection of suitable earthing system easier. The grounding system earth surface potential under transient condition is investigated