Which device is used to protect circuits from overloads and short circuits?

• A. Transformer.
• B. Fuse.
• C. Circuit breaker.
• D. Isolator switch.

Answer: (C)

The device that is used to protect circuits from overloads and short circuits is the circuit breaker. Circuit breakers are designed to automatically interrupt the flow of electricity in a circuit when they detect an overload or a short circuit condition. This interruption prevents further damage to the circuit, wiring, and connected devices, and it also reduces the risk of fire caused by overheating wires.

When there is an overload, circuit breakers sense the excessive current and "trip," cutting off the power supply. In the case of a short circuit, the sudden surge of current is also detected, leading to an immediate disconnection. Circuit breakers can be reset after they trip, which makes them user-friendly and convenient for home and commercial electrical systems.

In contrast, while fuses also serve to protect circuits from overloads and short circuits, they must be replaced once they have blown. Transformers and isolator switches do not provide overload protection; transformers are used to change voltage levels, and isolator switches are meant for isolating circuits for maintenance and safety but do not disconnect under overload conditions. This makes the circuit breaker the most effective and practical choice for circuit protection in residential electrical systems.