Enamelled wire is painted for copper and aluminum round and flat wire used in motors, transformers, generators and electrical measuring instruments. They are cured to the wire by heating. The main function of the resulting coating is electrical insulation. Magnet wire is also described as primary insulation. Coated wire is sometimes referred to as "magnet wire".

Wire enamel is suitable for copper and aluminium wire with up to 30 layers. This provides electrical insulation and helps the windings avoid short circuits. These wire enamels must also have very good chemical and thermal resistance, must adhere very well to copper or aluminium wires and have excellent mechanical stability.

In some cases, such as when used in inverter-driven motors, suitable insulation should resist partial discharges that can cause short circuits and failures in the motor. Coated wires vary by application, and some may be smaller than the diameter of a human hair.

In heavy electric motors in wind turbines, round or flat wires can be up to several millimeters in diameter. The use of wire enamel depends on the shape and diameter of the wire to be coated. Horizontal or vertical application, or application using a die or felt, are typical wire coating methods.