Which device acts as both a protective device and switching device?

The circuit breaker serves as both a protective device and a switching device, making it the correct answer. As a protective device, it is designed to automatically interrupt the flow of electricity in the event of an overload or short circuit, thereby protecting the electrical circuit from damage and preventing potential hazards such as fires.

In addition to its protective role, a circuit breaker also functions as a switching device, allowing users to manually turn the circuit on or off. This dual capability makes it a versatile choice for managing electrical systems, providing both safety and convenience.

In contrast, fuses, whether single element or dual element, primarily serve as protective devices. They operate by melting a metal wire when the current exceeds a certain level, which interrupts the circuit. However, they do not allow for easy manual operation to switch the circuit on or off like a circuit breaker does. Therefore, while fuses are effective at providing overcurrent protection, they lack the dual functionality of switching like a circuit breaker.