Validation of the Calculation and Measurement Techniques of Earth Resistance Values

Much research has been published in the literature on the mathematical approaches to obtain the most accurate earth resistance and resistivity values. However, the published research only conducted the comparisons among the mathematical/computational techniques and so far none has conducted validation tests of these mathematical/computational methods against the real earth resistance measurement at real field sites. Thus, the main contribution of this research is to show the validity of the formulas available in the literature against the measured earth resistance value at field site. The earth resistance values at three field sites for the earthing systems consists of two, three and four rods were obtained with i) calculation, where the earth resistivity is first measured, which later interpreted into 2 layers earth and used to calculate for the earth resistance and ii) measurements using a Fall-of-Potential Method. The results from this present study can help to validate the mathematical approaches in some published work against the measurement results. Also, this is the first time this kind of comparison study between the calculated and measured for two layers soil model is presented, which can help to improve the earth resistance formulas in a future, since the calculation of earth resistance is important especially at the preliminary earthing system designs.