Copper wire is a resistance alloy mainly composed of copper and nickel. It is usually composed of 55% copper and 45% nickel, with a low temperature coefficient of resistance, a wide range of operating temperatures (below 480 ℃), good processing and welding performance. Copper wire is mainly used to make resistors and components in instruments, electronic equipment, and industrial equipment, and is suitable for use in AC circuits. ‌

In addition, there is a new type of constantan resistance alloy, which is a copper based alloy with similar electrical resistivity and temperature coefficient to constantan, but with lower price and poorer oxidation resistance. New constantan can replace constantan wire resistance alloy in some aspects, but in the production of fine resistors, manganese copper has higher accuracy.