why power cables are to be earthed at both ends?
To reduce the risk of electric shock. There are always leakage electrons from the power cable to the metalic equipment body, electric pole, and any metal part that are near to the power cable, which makes potential source of static electricity and thereby electric shock. To minimize this hazard by providing a path for the electrons to the earth is provided by the earthing.
Its called the M.E.N. system. It stands for Multiple Earth Neutral. The neutral of an appliance acts as a return, held at a low potential by earthing at each house, using rods into the ground, transformers in the street with earths, and earth mats where required when soils are not conductive. When a fault occurs to earth the low earthing point causes the fuse / breaker to trip. GL
