Question

Which of the following factors influence earth resistance?

a. Temperature of soil

b. Moisture content of soil

c. Depth at which the electrode is embedded

d. Quality of coal dust and charcoal in the earth electrode pit.

1. Only a, b and c
2. Only a, c and d
3. a, b, c and d
4. Only a, b and d

Answer 1

Correct Answer - Option 3 : a, b, c and d

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, quality of coal dust and charcoal in the earth electrode pit.
• 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