In a wye underground system, what is required for shielded cable that is not needed for concentric cable?

In a wye underground system, a neutral conductor is essential for the proper operation of the system. This is particularly important in scenarios where loads are unbalanced, as the neutral helps to return unbalanced current and maintains voltage stability. Shielded cable typically requires a neutral to manage the phase relationships and balance the load across the three phases effectively in a wye configuration.

Concentric cable, on the other hand, does not necessitate a neutral in the same way because it has an inherent design that allows for a more balanced load distribution among its conductors. This design is less susceptible to issues arising from unbalanced loads, allowing it to operate effectively without a separate neutral.

In summary, the requirement of a neutral conductor in a wye underground system for shielded cable is key for maintaining stability during unbalanced load conditions, whereas concentric cable's design mitigates the need for this additional component.