In a grounding electrode system, what is the minimum size grounding electrode conductor permissible?

The minimum size grounding electrode conductor is determined by the grounding electrode system's purpose, which is to connect the grounding electrodes, such as ground rods or plates, to the electrical system. According to the National Electrical Code (NEC), the minimum size for a grounding electrode conductor typically corresponds to the size of the largest ungrounded conductor but can also be influenced by other factors such as building type and material.

In most cases, the minimum size conductor allowable for grounding purposes is 6 AWG. This is primarily to ensure sufficient conductivity and mechanical strength while also providing an adequate path for fault currents. A 6 AWG grounding electrode conductor provides a good balance of protection and practicality, ensuring that the system can adequately handle any ground fault currents that may occur, while also complying with safety standards.

Other conductor sizes like 8 AWG, 10 AWG, and 2 AWG do not meet the minimum requirements for grounding in typical residential and commercial installations based on the NEC guidelines, which is why they would not be the correct answer.