nonconductive

Nonconductive describes materials that do not readily allow the flow of electric current. In practice it is used to refer to insulating materials that impede electrical conduction, as opposed to conductive or semiconductive materials. The property arises from the material's high resistivity and its ability to resist charge movement under ordinary voltages.

Common nonconductive materials include plastics such as polyethylene and vinyl, ceramics, glass, rubber, wood, and many fluids such as air or oil used as dielectrics. These materials are used in electrical systems to isolate conductive components, enclose hardware, or coat wires and circuits, thereby reducing the risk of short circuits and electric shocks. They may also serve as barriers in housings, panels, or printed circuit boards.

Electrical nonconductivity is usually complemented by good dielectric strength, the ability to withstand high voltages without breakdown. The performance of nonconductive materials can be affected by moisture, temperature, aging, and mechanical stress. Some materials may become more conductive when exposed to high humidity, ultraviolet radiation, or chemical attack, and all insulators have a finite breakdown voltage beyond which they conduct abruptly.

Nonconductive materials are often referred to as insulators or dielectrics. In fluid form, dielectric liquids (insulating oils) are used to insulate and cool electrical equipment. The term may also describe coatings, encapsulants, or substrates designed to prevent electrical leakage.