Comparison of soil resistivity as measured by a three-point or four-point method

초록

In order to effectively design grounding systems, it is essential to accurately determine the soil resistivity at the desired location of the connection to the earth. This paper presents a comparison of resulting soil resistivity obtained from measurements made with three-point and four-point fall-of-potential techniques. The soil resistivity-probe spacing ( ) curve obtained from the four-point method in undisturbed earth agrees well with the soil resistivity - depth of the driven rod ( ) curve obtained from the three-electrode method based on the fall-of- potential method. However, the curve in disturbed earth with moisture and freezing are significantly different to the curves. The curve is considerably sensitive to the freezing and the moisture present on the earth surface compared to the curve. Thus, to accurately determine the actual earth resistivity, it is necessary to take into account the earth surface and nearby circumferential conditions when measuring soil resistivity.