Insulators

Electrical insulators are devices made up of a given material whose internal electric charges do not flow freely; meaning very little electric current will flow through it under the influence of an electric field. Most insulators are either made out of porcelain or polymer materials. The property that distinguishes an insulator is its resistivity. A perfect insulator does not exist because they all contain small numbers of mobile charges (charge carriers) which can carry current. In addition, all insulators become electrically conductive when a sufficiently large voltage is applied, this is due to the electric field tearing electrons away from the atoms. This is known as the breakdown voltage of an insulator. Insulators are used in electrical equipment to support and separate electrical conductors without allowing currents through themselves. The term insulator is also used more specifically to refer to insulating supports used to attach electric power distribution or transmission lines to utility poles and transmission towers. They support the weight of the suspended wires without allowing the current to flow through the tower to ground.