A new method of measuring earth resistance by using the three-electrode method in which the grounding conductor is not disconnected from the earth electrode

It is often difficult to measure earth resistance in NTT´s telecommunication buildings because of the currently installed grounding system and the paving of the surrounding area. Last year, the authors developed a simple method for measuring earth resistance by using one assistant electrode, in which a grounding conductor did not need to be removed. However, this so-called two-electrode method has a small degree of error than the conventional three-electrode method. They have therefore tried to improve this method by using another assistant electrode for new three-electrode method. The results obtained by conducting indoor experiments and field tests compared with the conventional method, along with errors of two-electrode method are discussed in this paper