What must be done to non-current-carrying metal parts that might become energized?

To prevent electrical shock hazards and ensure safety, non-current-carrying metal parts that might inadvertently become energized must be connected to ground. Grounding these parts creates a low-resistance path for electrical current to flow safely away from people and equipment, reducing the risk of electric shock or fire hazards. If such metal components were to become energized due to insulation failure or accidental contact with live conductors, grounding effectively helps to ensure that any fault current is directed away from individuals and sensitive equipment.

The other options may involve safety measures, but they do not provide the same level of protection as proper grounding. Isolating metal parts may prevent direct contact but does not mitigate the risk of them becoming energized. Covering parts with insulation or painting them with non-conductive paint can be helpful in certain circumstances, yet these methods do not offer the same fail-safe benefits that grounding provides in the case of accidental energization.