An 80-amp feeder is installed to supply power to an agricultural barn. The feeder conductors are 4 AWG. What is the required gauge of the EGC?

The required gauge of the Equipment Grounding Conductor (EGC) is determined in accordance with the National Electrical Code (NEC), specifically referencing the size of the feeder conductors and the overall application.

In this case, for an 80-amp feeder using 4 AWG conductors, the NEC outlines that the minimum size for an equipment grounding conductor must be based on the size of the ungrounded conductors. Under NEC Table 250.122, for feeders supplying up to 100 amps, a 4 AWG copper conductor requires an equipment grounding conductor of at least 4 AWG when the conductors are copper. This is because the EGC is sized to ensure it can safely handle any potential fault currents that may occur, providing a reliable path back to the grounding system to clear faults and enhance safety.

Choosing a smaller gauge, such as 6 AWG or 8 AWG, would not meet the NEC requirements for a system of this size, compromising safety and potentially leading to code violations. Therefore, 4 AWG for the EGC is compliant and necessary for proper functioning and safety in this installation scenario.