Look at the iron in the figure. It is not earthed. If a loose live wire touches the case, it would be raise to 240 V. If you touch the case, this voltage could drive enough current through your body to kill you. If the case is properly earthed contact with live wire would cause a large current to pass along the earth wire into the ground. The fuse in the plug would melt, cutting off the electricity supply. It is best to earth electrical equipment that is meant to be handled.
Equipment such as electric kettles, irons, guitars, cookers, table lamps, washing machines, vacuum cleaners, refrigerators and electric heaters should be securely connected to the earth. Some equipment that carries the label is double insulated. This need not be earthed.
Electric Appliances mainly used at home