The earth wire is connected to the casing of the appliance. If the live wire touches the casing, the earth wire provides a path for the electricity to flow. This blows the fuse and switches the appliance off, leaving you safe.
Electrical Safety Check Test Answers
11. The earth wire is a safety device which is connected to the casing of appliances. The earth wire provides a path for the electrical current to flow if the live wire becomes loose and touches the casing making it live. The large current which flows through the earth wire will melt the fuse switching the appliance off.