Insulators are materials that do not easily lose or gain electricity. Examples of good insulators are glass, mica, and diamond.

Insulators are used to keep electricity from traveling to the point of ground. Point of ground is determined when electricity has a path to earth. If electricity travels to the point of ground, there would be an explosion.

Let's say that electricity needs to travel from a power company to your home. In order to do this, electricity is sent through a conductor. A conductor is a material that can easily gain and lose electricity. An insulator is placed below the conductor to keep the electricity from moving somewhere other than your house.

The pictures above show insulators used on top of telephone poles.

Without an insulator, energy would move out of its conductor. Therefore, electricity would not travel to where it is needed.

The wires in this power cable (silver) are surrounded by insulation (grey) and a plastic coating (black).   This typical household wiring has two insulated wires and an uninsulated ground wire. The set of wires is surrounded by additional insulation.  These wire connecting cables are coated with insulation and different color plastic coatings. The colors do not effect their use.

The pictures above show an insulator for an electric hot water heater.