What is the minimum size of an equipment grounding conductor required for a 1,000-ampere feeder supplying a separate building or structure?

The minimum size of an equipment grounding conductor for a 1,000-ampere feeder supplying a separate building or structure is determined based on the requirements outlined in the National Electrical Code (NEC). When evaluating this specific situation, the NEC provides tables that prescribe the minimum sizes for grounding conductors based on the ampacity of the feeder.

For a feeder with a rating of 1,000 amperes, the NEC specifies that the minimum equipment grounding conductor for aluminum would typically be 4/0 AWG. This size ensures adequate grounding to handle potential fault currents, providing both safety and effective protection against electrical hazards. A larger conductor size, such as 4/0 AWG, is required as it increases the conductivity and reduces the resistance, which is crucial in fault conditions where grounding conductors must perform effectively.

In contrast, smaller sizes, such as 2 AWG aluminum or 4 AWG copper, do not meet the NEC requirements for such a high ampacity. The emphasis on using larger grounding conductors is due to the need for proper ground fault protection, which is essential for preventing electrical shock and ensuring equipment safety and reliability.