Abstract: The electrical resistance in an earthing system basically consists of resistance of earthing conductors that is negligible and earth transresistance that depends on earth specific resistance varies with earth geology. In our country, designs are made considering earth specific resistance as 100O without making any measurements in most practices because these measurements are time consuming and costly. But this may cause important security gaps. This study is carried out to determine the answer of the question whether earth specific resistance could be determined without making any measurements? In this study geological data-earth specific resistance relation is modelled with decision tree classification algorithms in Weka software environment. The study is performed on the field that is located in Turkey. Estimation results yielded significant outputs. We expect this study to be pioneer for more widespread practices enhancing field diversity.

Keywords: Classification model, data mining, decision tree algorithm, earth specific resistance, earthing system, geological structure.