Abstract
Currently, the way of measuring earthing resistance is the fall of potential method which is used extensively both in Japan and worldwide. However, in overcrowded areas particularly in urban districts there is not enough space for taking measurements due to limited sites，the greater size of buildings and asphalt and concrete paving. Furthermore, there is the difficulty of inserting an auxiliary electrode. There are examples where large building sites with various underground obstacles （materials） such as piping，electric wise and concrete settlement, influence the measured earthing resistance. The present stste requires an improvement in earthing resistance measurement technology. Hence, the fall of potential method is used to simulate the earthing resistance measurement at the points of inserting the auxiliary electrode.
