What do fuses or breakers do when specific safe conditions are surpassed?

Fuses and circuit breakers are protective devices designed to ensure safety in electrical systems by interrupting the flow of electricity when certain predetermined safe conditions are breached. Specifically, they respond to overcurrent situations, which can occur due to various reasons such as short circuits, overloads, or equipment failures.

When the current exceeds the rated limit of the fuse or breaker, its internal mechanism activates to disconnect the circuit. This interruption protects not only the electrical circuit but also prevents potential hazards like overheating, fires, and equipment damage. Therefore, the correct answer highlights the primary function of these devices, which is to cut off the power supply to prevent unsafe conditions and ensure the integrity of the electrical system.

In contrast, increasing voltage, providing additional current, or enhancing signal strength do not pertain to the safety function of fuses and breakers. These actions would potentially exacerbate unsafe conditions rather than mitigating risks.