What determines the amperage a fuse can hold before it melts?

The ability of a fuse to hold a specific level of amperage before it melts primarily relies on the size of the fuse wire. Fuses operate by melting a wire when the electrical current exceeds a designated limit. A larger gauge wire can handle more current due to its increased cross-sectional area, while a smaller gauge wire will melt at a lower current because it heats up more quickly due to its narrower diameter.

This melting point is a critical aspect of a fuse's design, ensuring that it acts as a protective device by interrupting the circuit when excessive current flows. The wire size is carefully chosen based on the fuse's rated amperage to ensure that it operates correctly within the intended circuit parameters.

While other factors like circuit type, voltage, and material can influence overall performance or characteristics of the fuse, the size of the wire is the primary determinative factor for the amperage rating and the point at which the fuse will melt and interrupt the circuit.