Grounding systems are fundamental components of protection systems for electrical systems and equipment, with a top priority assigned to their economic design. The ground resistance of ground-enhancement-material (GEM)-encased vertical and horizontal rods buried in a uniform soil is calculated based on the current sphere simulation technique (CSST). A relationship between ground resistance and the associated cost of rod installation is formulated to form an objective function for optimizing the ground resistance. For a vertical rod of 1.44 m in length and 16 mm in diameter, encased by GEM shell with diameter of 0.2 m and length of 1.5 m, the calculated ground resistance is 102% of that obtained by COMSOL. For a horizontal rod with the same dimensions, buried at a depth of 0.6 m, the optimal ground resistance is 108.6% of that of the vertical rod. However, the cost for the horizontal rod is almost 70% of that of the vertical rod at the optimal solution.