Fuses are rated based on ______.

Fuses are rated based on how much current they can withstand, which is crucial for their function in an electrical system. A fuse is designed to protect electrical circuits by interrupting the flow of current when it exceeds a certain level. This rating ensures that the fuse will blow and disconnect the circuit before any components can suffer damage from excessive current.

In contrast, while voltage threshold is important for determining the appropriate voltage at which a fuse can operate safely, it does not directly represent the fuse's primary function. Resistance is an electrical property but is not used to rate fuses; rather, it refers to how much the material opposes the flow of current. Duration of operation is also not relevant in the context of how fuses are rated, as it does not pertain to their primary role of current protection. Thus, the focus on current capacity is what classifies fuses for safe and effective utilization in electrical systems.