How should the neutral conductor for a service be sized?

The correct approach to sizing the neutral conductor for a service is to ensure it can carry both maximum unbalanced and ground-fault currents. This is essential for safety and functionality in electrical systems.

Sizing the neutral for maximum unbalanced current is crucial because the neutral conductor primarily carries the imbalance from the phase conductors in a multi-phase system. If you only consider unbalanced currents, the neutral may be under-sized for situations where ground-fault currents occur.

Additionally, a ground-fault condition can introduce significant current through the neutral conductor, especially in systems where equipment is grounded directly. If the neutral isn’t sized to handle this combined scenario, it can lead to overheating and potential failure of the neutral conductor, posing serious safety hazards such as electrical fires or equipment damage.

By ensuring that the neutral conductor is able to handle both the unbalanced loads from the connected devices and any possible ground-fault currents, the installation adheres to safety standards and reduces risks during operation. Therefore, sizing the neutral for both conditions is a comprehensive approach to electrical safety.