hmmm, here is a very elementary concept to most of you. The situation is that a live wire comes into contact with the metal casing of a fan which is earthed. Connected to the live wire is a fuse of rating 5A. Since it is earthed, the excess charges will be conducted away. This will pose no danger to the handlers. However, the fuse is still used. Why is there a need to use the fuse? Is it primarily to detect the fault? Or is it serving another purpose?