Ontario Operator-in-Training (OIT) Practice Exam

What is the primary function of fuses and circuit breakers?

1. To increase current flow

2. To maintain a constant voltage

3. To burn out or break a circuit to prevent wire burning

4. To enhance power supply

The correct answer is: To burn out or break a circuit to prevent wire burning

Fuses and circuit breakers serve a crucial safety function in electrical systems. Their primary role is to protect electrical circuits from excessive current flow that can lead to overheating and potentially cause fire hazards. When the current exceeds a safe level, a fuse will melt and break the circuit, while a circuit breaker will trip and interrupt the flow of electricity. This action prevents wires from burning out, which is essential for protecting not only the electrical components but also the overall safety of the system and surrounding environment. In this context, other options do not align with the primary function of fuses and circuit breakers. Increasing current flow or maintaining a constant voltage does not reflect their protective role. Enhancing power supply is also not relevant as the function is not about increasing capacity but about safeguarding existing circuits by cutting off current that poses a risk.