Efficient ground grid designs in layered soils

A detailed analysis qf the eflects of ground grid configuration on grounding performance has been carried out ,for uniform and horizontally stratified soils with multiple laytw. The results of the analysis reveal thut the most efficient and cost-effective design is highly dependent on soil structure typt’ and characteristics. In the absence of ground rods, grounding grids with uniform mesh size are quite efficient in soils having a thin (relative to grid size) high resistivity (relative to the lower layers) top soil, while grids with small mesh size ut the periphery of the grid provide optimum peijFOrmance in uniform soils and soils with low resistivity top soils. Ground rods were found to be effective only when a significant portion of their length is in contact with a low resistivity soil, as expected.