SOLUTION

From the point of view of safety, all parts of electrical equipment should be kept at earth potential, therefore these are connected to an earth electrode. The earth electrode provides a path of low resistance to the leakage currents to flow to the earth.

For safety, the resistance of the grounding electrode should be low. If the resistance is high, then due to the maximum current in the event of a fault, the equipment connected to the supply may burn. Therefore the resistance is kept low, in homes the value of electric resistance is kept as 0.5Ω to 1Ω.

(i) In the event of overvoltage which may occur due to lightning discharges and other causes it is essential to ensure that excessive overvoltages are not induced in the parts of the equipment.

ii) Also, the neutral in a three-phase circuit is connected to the earth in order to stabilize the potential of other circuits