Double insulation
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:
