What is the smallest size of wire allowed on grounding equipment?

The smallest size of wire allowed on grounding equipment is indeed #2 Copper. This size is specified in the National Electrical Code (NEC) for grounding conductors to ensure they can safely handle fault currents without overheating.

Using #2 Copper wire provides adequate conductivity and strength for grounding applications, which are crucial for the safety and reliability of electrical systems. Grounding conductors must be able to carry fault current safely away from equipment and personnel to the ground, especially in the event of a malfunction or a lightning strike.

The options for sizes smaller than #2 Copper, such as #3 Copper or #4 Copper, do not meet the minimum requirements set forth by safety standards and can pose risks of inadequate fault current handling. Larger sizes, while acceptable, are unnecessary and may not be as cost-effective for many grounding applications. Therefore, #2 Copper represents a balanced choice for grounding effectiveness and regulatory compliance.