The grounding electrode conductor for a separately derived system is sized based on what factors?

The grounding electrode conductor for a separately derived system is sized primarily based on the circular mil area of the ungrounded system conductor. This is because the ungrounded conductors are critical in determining the potential fault current that the grounding system is required to safely clear. The grounding electrode conductor must be adequately sized to conduct these fault currents without overheating or failing, ensuring that the grounding system is effectively integrated into the overall safety of the electrical installation.

By referencing the circular mil area of the ungrounded system conductor, you ensure that the size of the grounding electrode conductor corresponds to the maximum load it might encounter during a fault condition. This sizing helps in maintaining adequate protection for both the equipment and personnel by facilitating proper operation of overcurrent devices and minimizing the risk of electric shock.

The other options, while related to grounding considerations, do not specifically influence the size of the grounding electrode conductor in the context of its purpose and function within a separately derived system. For instance, the grounded conductor and the overall system voltage are important in different contexts of grounding and bonding but do not directly determine the required size of the grounding electrode conductor.