Why is tungsten not used as a fuse wire ?

Tungsten is not used as a fuse wire primarily due to its high melting point and resistance to heat. Fuses are designed to protect electrical circuits by melting (blowing) when current exceeds a safe level, thereby interrupting the circuit and preventing damage or hazards such as fires. Tungsten has an extremely high melting point of around 3422 degrees Celsius (6192 degrees Fahrenheit), which makes it unsuitable for use as a fuse wire because it would require excessively high currents to melt, defeating the purpose of providing protection at lower, safer thresholds. As a result, metals with lower melting points and suitable electrical resistance, such as copper, aluminum, or alloys like nichrome, are preferred for fuse wires to ensure reliable and predictable operation under normal operating conditions.

Tungsten is not used in fuses due to its impractically high melting point and the specific requirements of fuse operation. Fuses are safety devices designed to protect electrical circuits by melting (blowing) when current exceeds a predetermined threshold, thereby interrupting the circuit and preventing damage or hazards such as overheating or fire. Tungsten’s exceptionally high melting point, around 3422 degrees Celsius (6192 degrees Fahrenheit), means that it would require dangerously high current levels to melt, defeating the purpose of providing overcurrent protection at lower, safer thresholds. Therefore, metals with lower melting points and suitable electrical resistivity, such as copper, aluminum, or alloys like nichrome, are commonly chosen for fuse wires to ensure reliable and effective protection under normal operating conditions.

Nichrome is used instead of tungsten for fuse wires primarily due to its lower melting point and suitable electrical properties. Nichrome is an alloy of nickel and chromium known for its high resistivity and moderate melting point, making it well-suited for applications where controlled heating and electrical resistance are essential. In fuses, nichrome allows for predictable melting at specified current levels, thereby protecting electrical circuits from overcurrent conditions that could lead to damage or hazards. Unlike tungsten, which has an extremely high melting point impractical for fuse applications, nichrome strikes a balance between electrical resistance, thermal stability, and reliability, making it a preferred material for fuse wires in various electrical and electronic devices.

Tungsten is used in bulbs primarily because of its high melting point and ability to withstand high temperatures without deforming or vaporizing. Incandescent light bulbs operate by passing an electric current through a tungsten filament, which heats up and emits visible light as it reaches temperatures of around 2500 degrees Celsius (4532 degrees Fahrenheit). Tungsten’s high melting point ensures that the filament remains intact and continues to emit light over an extended period, providing efficient illumination. However, for fuse applications, where the primary requirement is to melt at specific current levels to protect circuits, tungsten’s high melting point becomes a drawback as it would require excessively high currents to blow, thus compromising its effectiveness as a fuse material. Therefore, while tungsten is suitable for bulbs due to its high-temperature stability, other materials with lower melting points and suitable electrical characteristics, such as nichrome or specific alloys, are preferred for fuse applications to ensure reliable protection of electrical circuits.