Double Insulation

Some appliances need an earth wire and some do not.

An appliance needs an earth wire if the case is made of metal. If this is the case then a wire touching the case can make it live so that if someone touches it they can receive an electric shock

If the appliance has an insulating – plastic – case and no exposed metal parts it cannot become live so cannot cause electrocution. The device is said to be double insulated. Double insulated devices carry this symbol of a square inside a square.

Many heating appliance – fan heaters, hair dryers or kettle – are double insulated. These devices MUST be double insulated since they are regularly handled so the cases cannot under any circumstances become live. With a hair dryer this is especially important since these are sometimes used in the bathroom or with wet hands.

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