Q. What does the NEC mean by an auxiliary grounding electrode?
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A. Auxiliary electrodes are permitted, but they have no Code requirements since they serve no purpose related to electrical safety. (Figure)
Caution: An auxiliary electrode typically serves no useful purpose within the scope of the NEC, and in some cases it may actually cause equipment failures by providing a path for lightning to travel through electronic equipment.
Danger: Because the contact resistance of an electrode to the earth is so great, very little fault current returns to the power supply if the earth is the only fault current return path. The result is the circuit overcurrent protection device won’t open and clear the ground fault, and all metal parts associated with the electrical installation, metal piping, and structural building steel will become and remain energized.