A cable contains strands of wire. Some cables are thin and flexible. They are used to connect electrical equipment such as computers and television sets to the mains. The cables which carry electricity from a power station are much thicker.

Cables that are used in the home are flexible so that electrical equipment like a vacuum cleaner can be moved around easily. The cables in the home are made flexible by using many strands of wire that are twisted together. You are kept protected from the current in the wire by the plastic coating around the wire. The plastic is an insulator and does not let the current flow through it.

The cables which carry electricity from power stations to homes are very thick. Overhead power cables do not have an insulating coat. The air around them acts as an insulator to stop the current reaching the ground.

The power cables which are buried underground have a plastic coating. This keeps water in the ground from reaching the wires. These cables are also protected from accidental damage by a metal casing.