Is it true that one of the two 120-volt wires supplied by a 277-volt circuit must be grounded according to the NEC®?

According to the National Electrical Code (NEC), it is indeed true that one of the two 120-volt wires supplied by a 277-volt circuit must be grounded. The NEC outlines specific grounding requirements to enhance safety and protect both people and property from electrical faults. In systems connected to a 277-volt source, which is often used for lighting applications in commercial buildings, one conductor is designated as grounded. This grounded conductor serves as a path for fault currents and helps ensure that overcurrent devices operate correctly under fault conditions.

This grounding is crucial because it helps to prevent shock hazards and maintains the safety and reliability of the electrical installation. Proper grounding practices mitigate the risks associated with electrical faults and provide a clear reference point for the electrical system. Thus, the requirement of grounding one of the conductors aligns with NEC provisions and safety protocols, confirming the statement as true.