What is the function of a circuit breaker?

• A. To protect electrical circuits from overloads.
• B. To reduce voltage spikes in the circuit.
• C. To switch circuits manually on and off.
• D. To monitor battery health and charging

Answer: (A)

Circuit breakers are protective devices that interrupt current when it becomes too high. This automatic trip safeguards wiring and components from overloads or short circuits, preventing overheating and the risk of fire. In a bus, they protect circuits for lighting, HVAC, doors, and propulsion by quickly opening the circuit when a fault is detected, and you can reset the breaker after the fault is cleared to restore power. They’re not meant to reduce voltage spikes (that’s the job of surge protection devices) or to monitor battery health (that’s handled by battery management systems). Some breakers can be manually reset, but their primary role is automatic protection.