1. A fuse contains a thin wire that heats up and melts if too much current passes through it. The rating of a fuse is the maximum current that can pass through it without melting the fuse wire.

2. The earth wire creates a safe route for the current to flow through, if the live wire touches the casing. This prevents the user from getting an electric shock if he touches the appliance. The Earth wire has a very low resistance so a large current flows, which breaks the fuse and disconnects the appliance.

3. Double insulated appliances have plastic cases. This means that the case cannot become live, because plastic does not conduct electricity.