What is the primary purpose of a circuit breaker?

The primary purpose of a circuit breaker is to protect circuits from overcurrent. When the current flowing through a circuit exceeds a certain threshold, typically due to a short circuit or an overload, the circuit breaker automatically interrupts the flow of electricity. This prevents damage to the wiring, equipment, and reduces the risk of electrical fires.

Circuit breakers serve as a safety device, ensuring that the electrical system operates within safe limits. If a fault condition occurs and the load increases beyond the designated capacity, the circuit breaker will trip, effectively cutting off the power supply and preventing potential hazards. The ability to reset the circuit breaker after it trips also enhances convenience over traditional fuses, which need to be replaced after blowing.

In contrast, other choices like transforming electrical energy or measuring electrical load pertain to different devices and functions within an electrical system. Controlling lighting fixtures involves the use of switches or dimmers rather than a circuit breaker. Therefore, the choice that accurately reflects the primary function of a circuit breaker is protecting circuits from overcurrent.