Where must non current-carrying metal parts be grounded and bonded according to grounding requirements?

• A. Only at the main service entrance
• B. At the portal and at maximum intervals of 10 ft
• C. At every joint in the system
• D. Only when equipment is installed underground

Answer: (B)

When non-current-carrying metal parts are capable of becoming energized, they must be connected to the equipment grounding conductor to provide a continuous, low-impedance path back to the source. Bonding these parts at strategic points keeps the entire metalwork at the same potential so that a fault current will quickly trip protective devices and minimize shock risk.

Bonding at portal points and at maximum intervals of 10 ft ensures continuity along long runs and at joins where sections come together. This way, even if a connection shifts or a section is added, the fault path remains intact rather than breaking at a joint or distant connection. Grounding only at the main service entrance could leave portions unbonded, and bonding at every joint or only underground installations would be impractical or unnecessary for typical layouts.