Wenner Four Pin Method for Soil Resistivity Test

Before design grounding system for the plant, soil resistivity shall determine first. This value of soil resistant will be an input in designing grounding system later (i.e. substation grounding, engine hall grounding and pump house grounding). To determine the soil resistivity value, there are several steps to be done.

First of all we will discuss a method used to determine the soil resistivity value.

This method known as Wenner four-pin method, developed by Dr. Frank Wenner, US Bureau of Standards in 1915. On these methods used four electrodes, two for current injection and two for voltage measurement.  The four electrodes embedded to the ground in straight line, the two outer electrodes are current electrode and two inner electrodes to measure voltage drop due to resistance of soil path when current passed between the outer electrodes.