NEC Commercial Electrical Practice Test

A fuse or circuit breaker must be connected in series with each what conductor?

1. Grounded

2. Neutral

3. Ungrounded

4. Regulated

The correct answer is: Ungrounded

The correct answer is ungrounded conductors. In electrical systems, ungrounded conductors are those that carry the current and do not have a direct connection to the ground. To protect these conductors from overloads and short circuits, a fuse or circuit breaker must be connected in series with them. This ensures that if a fault occurs, the protective device will interrupt the circuit, thereby preventing damage to the system and reducing the risk of fire or electrical shock. Grounded conductors refer to the neutral wires in a system that are connected to the earth ground, while the neutral conductor serves as the return path for current in a balanced system. These conductors typically handle different current characteristics and do not require a fuse or circuit breaker. Regulated conductors usually deal with circuits that have specific requirements and may not be a standard term used in circuit protection contexts like fuses or circuit breakers. Hence, they do not align with the protective needs that the question addresses. By connecting protective devices specifically to ungrounded conductors, systems are made safer and more reliable, ensuring that any faults are quickly addressed by disconnecting the affected portion of the circuit.