Comparative Evaluation of Ground Resistance Measurement Techniques and FEM-Based Modeling under Grounding Electrode Configurations

Abstract

Accurate estimation of ground resistance is essential for designing safe and reliable electrical grounding systems. This study investigates the performance of four representative electrode configurations—single rod, two parallel rods, three rods in a linear arrangement, and three rods in a delta arrangement—by combining experimental measurements with numerical modeling. The ground resistance values were measured using the 3-pole Fall-of-Potential (FOP) method and the 4-pole Wenner method and compared with results simulated via the Finite Element Method (FEM) implemented in the COMSOL Multiphysics Program. The analytical solutions were set under homogeneous soil conditions at the test site. The soil resistivity was first determined experimentally to establish the boundary conditions for the FEM model. The numerical model's accuracy was confirmed by simulation results that closely matched field measurements, with a relative error of less than 3%.  Moreover, the results revealed that increasing the number of grounding rods effectively reduces total earth resistance. However, the reduction is nonlinear due to mutual coupling between the adjacent electrodes. The delta configuration provided the lowest resistance, followed by the three-rod linear arrangement. Overall, the study demonstrates that FEM analysis achieves high accuracy in predicting ground resistance under uniform soil conditions. The integration of numerical and experimental approaches supports the development of cost-effective and technically robust grounding designs for high-voltage and power distribution systems.