Analytical Expressions for the Resistance of Rodbeds and of Combined Grounding Systems in Nonuniform Soil

The modifications are suggested of Schwarz´s formulas for the resistance of rodbeds and for the mutual resistance of grid and rodbed component parts of the combined grounding systems which enable the application at nonuniform , two - layer soils. These expressions , together with a formerly derived formula for grid resistances, provide the necessary tools for evaluating the resistance of combined grounding systems. A simple empirical formula for the practical assessment of this resistance is also given.