How is the size of a grounding conductor determined in an installation?

The size of a grounding conductor in an electrical installation is determined using the NEC ampacity tables. These tables provide specific guidelines based on various factors, including the type of conductor, its material, and the application conditions. The National Electrical Code (NEC) outlines these tables to ensure that the grounding system is capable of safely carrying any fault current that may occur during a fault condition, thereby protecting both the electrical system and personnel.

By following these tables, electricians can ensure that the grounding conductor is appropriately sized to meet safety requirements and provide adequate protection against electrical faults. This is crucial because an undersized grounding conductor may not effectively divert fault current to the ground, resulting in potential hazards such as electrical shock or equipment damage.

Other methods mentioned, such as determining size based on the total load or the largest feeder, do not specifically address the unique requirements for grounding conductors, which are focused on fault current handling rather than regular operational loads.