If a commercial building has a three phase grounded delta supply, how many different incoming power supplies would be required?

In a three-phase grounded delta power supply system, only one incoming power supply is necessary to provide the required electrical power for the operations of a commercial building. A three-phase system utilizes three conductors, which carry electrical power in a balanced manner. This design allows for efficient power distribution across the electrical loads of the building.

The three-phase grounded delta system simplifies the wiring and reduces the number of connections needed compared to other configurations, such as a wye system, which might require additional neutral or grounding connections if not properly configured. With this system, all three phases are derived from a single power supply. This allows the building to effectively utilize the electrical power for various appliances, lighting, heating, and cooling systems efficiently.

Having just one incoming power supply enhances reliability and minimizes infrastructure costs, making it a practical choice for commercial installations. The other options suggesting multiple incoming supplies would imply redundancy or complexity that is unnecessary for a properly designed and grounded delta system.