In September, 2012, Enviroprobe performed a Fall-of-Potential survey in southern New Jersey. The purpose of the survey was to measure the electrical resistance of the grounding system for a new building. The survey utilized a AGI SuperSting R8 resistivity system with its standard passive cables.
There were four grounding wells around the building and they were interconnected with each other forming the grounding system. The dimension of this grounding system was in the scale of 100'x100'. Two of the these wells were tested to measure the electrical resistance to the earth. Each test was carried out using the “Fall of Potential” method specified in IEEE Standard 81. The method involves passing an electrical current into the ground well, the earth, and a remote current electrode forming a current loop, and noting the influence of this current in terms of voltage between the ground well under test and a test potential electrode. The results from these two tests were similar, confirming valid testing.