Complete Ground System Testing

brian john

Senior Member
Leesburg, VA
There are three basic ground tests, a 4-Point test performed to aid in designing a ground system for a site, a 3-point test is utilized to measure the resistance of an electrode to Earth (the electrode is isolated from the electrical distribution system) and a 2-point test (continuity test) is utilized to verify resistance to a known ground. All three tests require specialized test equipment. In the first test there is no existing electrical system or is utilized to design a new ground electrode system, in the last two tests whether the phase conductors are terminated or not is not important BUT in the 3-point test you have isolated (disconnected) the Grounding Electrode so a system outage would be prudent, in a 2point test you are often going into energized distribution equipment and as always be careful, safety first as working around energized systems requires special precautions.