What is the function of a circuit breaker in an electrical system?

The function of a circuit breaker is primarily to automatically shut down the electrical flow when a circuit becomes overloaded. This safety feature is crucial because when too much current flows through a circuit, it can cause overheating, potentially leading to equipment damage or even electrical fires. By interrupting the flow of electricity, circuit breakers help protect both the wiring and the devices connected to the circuit from harmful conditions that could result from excessive current.

In the context of the other options, providing power to circuits describes the role of the electrical supply itself rather than a circuit breaker. Increasing the voltage in a circuit refers to functions associated with transformers or power supplies, not circuit breakers. Connecting different circuits to each other relates to switches or junctions in electrical design, rather than the protective role of a circuit breaker. Therefore, the primary role of a circuit breaker is its protective function, making the chosen answer the most accurate representation of its purpose.