What device protects electrical circuits from overload on a ship?

• A. An ammeter.
• B. A circuit breaker (or fuses).
• C. A battery disconnect switch.
• D. A circuit monitor.

Answer: (B)

Protection from overload in ship electrical systems is provided by a device that automatically interrupts current when it becomes too high. A circuit breaker (or fuses) serves this purpose, opening the circuit to stop the flow of electricity during an overload or short circuit. Circuit breakers can be reset after a fault, while fuses must be replaced after they blow. This prevents overheating, insulation damage, and fires aboard. An ammeter only measures current, not protection. A battery disconnect switch isolates the battery but doesn’t automatically respond to overload. A circuit monitor offers status and alarms but doesn’t disconnect the circuit.