Metal enclosures for switches or circuit breakers should be connected to what?

Metal enclosures for switches or circuit breakers should be connected to the circuit equipment grounding conductor because this connection is essential for safety and proper functioning. The grounding conductor serves to ensure that any fault currents are safely directed to the ground, reducing the risk of electric shock or fire in case of a fault within the electrical system.

Grounding metal enclosures creates a low-resistance path for fault currents, enabling protective devices like circuit breakers to operate effectively and disconnect power in the event of an overload or short circuit. This practice upholds safety standards and is a fundamental requirement in electrical code regulations.

While connection to neutral conductors and phase conductors can be involved in the broader electrical design, they do not provide the specific protective benefit that grounding conductors do. Ground-fault interrupters serve a different function related to detecting ground faults, not specifically for the grounding of metal enclosures. Properly grounding enclosures mitigates electrical hazards, which is why this choice is the most appropriate and critical for safety.