How many incoming power supplies are needed in a commercial building with a three phase WYE 208V supply?

In a commercial building utilizing a three-phase WYE 208V power supply, only one incoming power supply is required. This is because a three-phase system consists of three conductors, which can carry the power needed for various equipment and systems. In a WYE configuration, the neutral point allows for the distribution of both 208V service between any two phases and 120V service from the neutral to any of the phases.

Having a single incoming supply means that the building can distribute the three-phase power to various loads efficiently without the need for multiple supplies. This design is not only common but also highly efficient, as it can serve a diverse range of equipment and lighting loads simultaneously, while maintaining balanced loads across the three phases.

In contrast, selecting two, three, or four incoming power supplies would be unnecessary for the requirements of most commercial operations. Each additional supply could lead to increased costs and complexity in power management without providing any additional benefit in a typical three-phase WYE system.