Correct Answer - Option 1 : Operating time
Concept:
The resistance of earth is the resistance between the earth and earth electrode. It depends on three factors.
- The resistance of earth electrode
- The contact resistance between electrode surface and soil
- The resistivity of soil between the electrode and earth
The resistivity of soil depends upon
- The electrical conductivity offered by a soil mainly due to electrolysis i.e. the resistivity of a soil is mainly electrolytic in nature
- So, concentration of water, salt (NaCl) and other chemical components in the soil largely determines its resistivity
- The chemical composition of the soil
- The temperature of the soil
-
Moisture; moist soil is best suited for earthing purpose
- It is normal practice to insert an earth electrode well below the ground level, to get a stable moist soil in depth
Explanation:
Earth resistance depends on the depth of the earth electrode, moisture, temperature but it does not depend on operating time.