Which one of the following is used in earth pit?

A. Salt and charcoal

B. Graphite and magnesium

C. Graphite and Silver

D. Aluminum and Iron

Answer: A. Salt and charcoal

Explanation: 

• Salt and charcoal are added in the earth pit for improving conductivity.
• Salt and charcoal increase the conductivity of the soil in the earth pit.
• As a result, the fault current finds it easy path through equipment to the earth.
• The alternate layers of charcoal and salt maintain low resistance for earth fault currents.