What primarily causes a fuse link to melt or blow?

A fuse link primarily melts or blows due to the current flowing through it exceeding its rated capacity. This occurs as the fuse is designed to protect electrical circuits by breaking the circuit when excessive current is detected, which typically happens when there is a fault or overload condition.

The resistance in the fuse itself plays a crucial role in the functioning of a fuse link. As current passes through the fuse, this resistance generates heat. When the current exceeds the limit for which the fuse is rated, the heat generated becomes intense enough to melt the conductive material of the fuse link. Consequently, this interrupts the flow of electricity and prevents further damage to the electrical system.

Other factors, such as voltage surges and environmental conditions, can influence the overall effectiveness of a fuse, but they are not the primary causes of the fuse melting. For instance, excess voltage alone does not cause a fuse to act unless it results in excessive current. Similarly, faulty installation may lead to other electrical issues but does not directly cause a fuse link to blow. Understanding the role of resistance in the fuse helps clarify why it is critical for circuit protection.