If the grounding electrode for a separate structure is a single ground rod, what is the largest size grounding electrode conductor required?

When determining the largest size grounding electrode conductor required for a grounding electrode such as a single ground rod, it is important to reference the National Electrical Code (NEC) guidelines, which dictate the minimum sizes based on the grounding electrode's material and the type of building.

For copper grounding electrode conductors, the NEC specifies that if a single ground rod is used as the grounding electrode, then the minimum conductor size is typically 6 AWG copper. This sizing ensures adequate conductivity and helps maintain safety by providing effective grounding, which is crucial for preventing electrical shock hazards and ensuring system stability.

Using 6 AWG copper meets the necessary requirements while also allowing for some degree of flexibility in installation, such as accommodating possible future load and ensuring reliability. Larger sizes, like 4 AWG or 2 AWG, may exceed what is required, while smaller sizes, like 10 AWG, do not meet the minimum requirements established for effective grounding practices.

Thus, the answer indicating 6 AWG copper is correct because it aligns directly with the regulations set forth for grounding systems involving single ground rods.