The resistance wire is used to control the amount of current in the circuit. High resistivity is better because shorter wires can be used. When the stability of electrical resistance is critical, the electrical resistivity and corrosion resistance temperature coefficient of the alloy are very important in material selection. When it is used for heating elements such as electric heaters and toasters, high resistivity and oxidation resistance are important.
Sometimes, the resistance wire is insulated by ceramic powder and wrapped in another alloy tube. This heating element is used in electric ovens and water heaters, and in a special form for cooktops.
Nickel-chromium alloy is a non-magnetic 80/20 alloy of nickel and chromium. It is the most common heating resistance wire because of its high resistivity and high temperature oxidation resistance. When used as a heating element, it is usually wound into a coil. One challenge when using nickel-chromium alloy wire is that ordinary tin-based solder will not adhere to it, so other methods (such as crimp connectors or screw terminals) must be used for power connections.