Why neutral is earthed?

Neutral earth is very necessary for observe the unbalaced laod of the 3 phase system. it is also useful for single phase supply and in lighting purpose. neutral earth is also earthed the short ciruit fauly current , which is flowing through neutral. this type it is very essencial for protection and safety purpose.

There are a number of reasons why the neutral of a supply is earthed (grounded). The first reason is to protect the low-voltage secondary side of the distribution tranformer in the event of a short circuit from the high-voltage secondary side (it will cause the protection on the high-voltage side to disconnect the transformer). The second reason is to establish a datum point for potentials measured on the secondary side of the tranformers -in particular, if the star-point of a three-phase transformer is not earthed, then an unbalanced load will result in unbalanced supply phase voltages, and a potential-difference between neutral and earth -both undesirable and dangerous.