Recreational Vehicle (RV) Technician Practice Test

What does a fusible link protect a DC circuit from?

1. Voltage fluctuations

2. Too much amperage

3. Resistance changes

4. Short circuits

The correct answer is: Too much amperage

A fusible link is designed primarily to protect a DC circuit from excessive current flow, which is referred to as too much amperage. When the current exceeds a predetermined threshold, the fusible link is designed to melt and break the circuit, thereby preventing damage to components and wiring due to overheating or fire caused by high current. This protective mechanism is particularly critical in DC circuits where current can become excessive during situations such as shorts or overloads. By interrupting the flow of current, the fusible link ensures that the circuit downstream does not experience the potentially damaging effects of this high amperage, thereby maintaining safety and function within the RV electrical system. Other factors like voltage fluctuations, resistance changes, and short circuits can lead to issues in a circuit but are not specifically what a fusible link is designed to protect against. Voltage fluctuations refer to changes in electrical potential that do not necessarily result from excessive current. Resistance changes could affect the current drawn, but the fusible link itself is not directly responsible for addressing resistance issues. Lastly, while short circuits can cause a significant increase in current flow that a fusible link would respond to, the link is fundamentally about protecting against the overall condition of too much amperage rather than specifically targeting short circuits alone.