Optimized grounding grid design using variable spacing technique

The envelope of earth surface potential curves is distinctly convex for grounding mats with many meshes. Such a condition is difficult to analyze with the established methods, which are primarily devised for calculating the corner mesh voltage. For this reason, a large, equally spaced grid may be overdesigned toward the center and underdesigned toward the perimeter. Aiming to remedy such problems, this paper analyzes and modifies the existing method of IEEE Guide No. 80, to allow a recursive point by point integration of surface gradients through consecutive meshes. A computer program for optimized grid design is described and the effect of spacing geometry is documented by computer plotted voltage profiles.