The purpose of a switch or a fuse is to break or connect an electric circuit, but they must be correctly connected in the home.
A switch or a fuse in an electrical circuit is always connected to the live wire so that the socket or appliance is not live when switched off.
If the switch or fuse is placed in the neutral wire, the electrical appliance is still connected to the high voltage live wire even when the switch is open, or the fuse is blown.
This could cause the user to get an electric shock if they touched the inside of the appliance.
Appliances encased in an insulating plastic case or body, such as hair dryers, mobile phone chargers and hand whisks do not need an Earth wire.
Such appliance are designed so that there are two levels of insulating material between the electrical parts of the appliance and any parts on the outside that can be touched.
These two layers are normally the insulating plastic case and the insulated cable carrying the live and neutral wires.
A metal attachment, such as a whisk blade, is fitted into a plastic case so that it does not make direct contact with the internal electrical parts.
Even though the device contains a live wire at mains voltage, there are two layers of plastic separating the user from this live wire.
The symbol for double insulation on an appliance is: