A switch or circuit breaker should disconnect all grounded conductors of a circuit ___.

A switch or circuit breaker should disconnect all grounded conductors of a circuit ___.

• A. I only
• B. III only
• C. I or III only
• D. II or III only

Answer: (D)

The important idea is that a disconnecting means must interrupt all conductors that make up the circuit so that it is truly de-energized for safe servicing. The grounded conductor (neutral) is part of the circuit, and in certain setups it can carry current or allow backfeed if only some conductors are opened. In multi‑wire branch circuits, for example, opening just one hot conductor can leave the neutral or the other leg energized, creating a shock risk or energizing connected equipment. Therefore, in the situations described, the switch or breaker should disconnect the grounded conductor along with the other conductors of the circuit to ensure complete de‑energization. The grounding conductor (equipment ground) is not intended to be switched, so it isn’t part of this required disconnection.

The important idea is that a disconnecting means must interrupt all conductors that make up the circuit so that it is truly de-energized for safe servicing. The grounded conductor (neutral) is part of the circuit, and in certain setups it can carry current or allow backfeed if only some conductors are opened. In multi‑wire branch circuits, for example, opening just one hot conductor can leave the neutral or the other leg energized, creating a shock risk or energizing connected equipment. Therefore, in the situations described, the switch or breaker should disconnect the grounded conductor along with the other conductors of the circuit to ensure complete de‑energization. The grounding conductor (equipment ground) is not intended to be switched, so it isn’t part of this required disconnection.