An electric household appliance that uses a metal conductor as a fuse connected in the power circuit. When the load or short-circuit capacity varies with the fuse, it melts due to its own heat, thereby breaking the circuit and preventing overcurrent. The fuse is simple in construction and easy to use, commonly used as a protective component in power systems, various electrical equipment, and electrical products.

The circuit breaker is crucially composed of three parts: the fusible element, the casing, and the rubber support. Among these, the fusible element is the core component that manipulates the circuit breaker's characteristics. The raw materials, specifications, and shapes of the fusible element influence the circuit breaker's performance.

Melted raw materials are divided into two major categories: low-melting point and high-melting point. Low-melting point materials, such as lead and aluminum alloys, have low melting points and are prone to melting, as they possess high resistance. Consequently, their cross-sectional specifications as molten materials are larger, leading to more alloy vapor during melting. They are only suitable for fuses with low breaking capacity.

High melting point materials such as copper and silver have high melting points, making them less prone to melting, yet due to their lower resistance, they can be formed into smaller cross-sectional sizes than low melting point alloys. This results in less alloy vapor when melting occurs, making them suitable for fuses with high breaking capacity. The shapes of the melt are divided into two types: linear and strip-like. Changing the cross-sectional shape can significantly alter the fuse's melting characteristics.