According to the NEC, which exposed metal parts must be grounded and bonded?

The National Electrical Code (NEC) mandates that all non-current-carrying metal parts must be grounded and bonded to ensure safety in electrical installations. This requirement is vital because grounding these exposed metal parts protects against electrical shocks and helps maintain the integrity of the electrical system.

By grounding all non-current-carrying metal parts, the NEC ensures that these surfaces do not become energized under fault conditions. If a fault occurs and the electrical current finds a path through these metal components, grounding provides a low-resistance path for the current to safely dissipate into the ground. This reduces the risk of electric shock or fire hazards, particularly in environments where people may come into contact with these metal parts.

This requirement applies to a wide range of installations, not just specific equipment, or those located near water, emphasizing the comprehensive safety measures that the NEC aims to implement across all electrical systems. Thus, grounding all non-current-carrying metal parts is both a safety best practice and a regulatory requirement under the NEC.