Grounding electrodes are typically buried metal objects; rods, interconnected arrays of rods, plates, grids, and various other designs aimed at putting a sufficient amount of metal in contact with the soil so as to safely and efficiently divert unwanted fault currents out of the electrical system and out of the protected facility. Upon construction, there is generally a ground resistance specification that is not to be exceeded. A performance test is run to assure that the system meets spec.
Grounding electrodes are typically buried metal objects; rods, interconnected arrays of rods, plates, grids, and various other designs aimed at putting a sufficient amount of metal in contact with the soil so as to safely and efficiently divert unwanted fault currents out of the electrical system and out of the protected facility. Upon construction, there is generally a ground resistance specification that is not to be exceeded. A performance test is run to assure that the system meets spec. Subsequently, maintenance tests should be run to assure that the system remains in spec, as grounding electrodes can deteriorate through corrosion, be damaged or destroyed in major fault clearance, or rise in resistance due to changes in the surrounding environment. So far, so good…