Question

To which wire is the metallic case of an electric appliance connected? Give the reason? 

Answer 1

If the live wire of a faulty appliance comes into direct contact with the metallic case due to some reason, then the appliance acquires the high potential of the live wire. This may result in shock if any person touches the body of the appliance. But if the appliance is earthed, then as soon as the live wire comes in to contact with the metallic case, high current flows through the case to the earth. The fuse connected to the appliance will also blow off, so the appliance get disconnected.