Is the neutral load of a feeder or service the maximum unbalance of the load?

The statement that the neutral load of a feeder or service is the maximum unbalance of the load is indeed true. In a three-phase system, the neutral conductor carries the unbalanced load that results from the differences in current between the three phases. This imbalance occurs because the loads on each phase may not be equal, leading to a net return path for the current through the neutral.

When the loads on the three phases are balanced, the current in the neutral is zero because the sum of the currents in the three phases cancels out. However, when there is an imbalance, such as when one phase has a heavier load than the others, the neutral conductor must carry the difference, which is equivalent to the maximum unbalanced load among the phases. Thus, understanding this concept is crucial for properly sizing the neutral conductor in accordance with the National Electrical Code (NEC) and for ensuring safety and compliance in electrical installations. Proper load balancing significantly reduces potential neutral current and enhances the safety and efficiency of the electrical system.