This lesson introduces earthing (grounding), its types, and its importance in electrical systems. Earthing provides safety by ensuring fault currents do not endanger users and protects equipment from hazards. Various earthing methods and their roles in preventing electrical shocks and stabilizing equipment operations are discussed.

1. Lesson 15: Earthing

2. Lesson Objectives
By the end of this lesson you will:
• Get introduced to earthing/grounding
• Identify the types of earthing
• Identify the importance of earthing

3. Introduction to Earthing/Grounding
Earthing or grounding is the term used for electrical connection to the
general mass of earth.
Earthing provides protection to personal and equipment by ensuring
operation of the protective gear and isolation of faulty circuit during:
• Insulation failure
• Accidental contact
• Lightning strike

4. Main Objectives of Earthing Systems
The main objectives of earthing system are:
1. Provide an alternative path for the fault current to flow so that it will
not endanger the user.
2. Ensure that all exposed conductive parts do not reach a dangerous
potential.
3. Maintain the voltage at any part of an electrical system at a known
value so as to prevent over current or excessive voltage on the
appliances or equipment.

5. Types of Earthing
There are various ways of doing Earthing:
1. Conventional Earthing
a. Pipe Earthing
b. GI Plat Earthing
c. Cast Iron plat Earthing
d. Copper plat Earthing
2. Maintenance Free Earthing
a. Factors Affecting and Value of Earth Electrode
Resistance
b. Electrode material
c. Electrode size
d. Material and size of earth wire
e. Moisture content of soil
f. Depth of electrode of underground
g. Quantity of dust and charcoal in earth pit

6. Importance of Earthing
• Earthing is necessary for proper functioning of certain equipments.
• Earthing is done also for preventing the operating personal from hazardous shocks caused damage
of the heating appliances.
• To save human life from danger of electrical shock or death. * To protect buildings, machinery &
appliances under fault conditions.
• To provide safe path to dissipate lighting and short circuit currents.
• To provide stable platform for operation of sensitive electronic equipments To provide protection
against static electricity from friction

7. Questions and Answers
Question 1: The objective of earthing or grounding is
a. To provide as low resistance possible to the ground
b. To provide as high resistance possible to the
ground
C. To provide flow of positive, negative and zero
sequence currents
d. None of the above

8. Questions and Answers
Question 1: The objective of earthing
or grounding is
a. To provide as low resistance
possible to the ground
b. To provide as high resistance
possible to the ground
C. To provide flow of positive,
negative and zero sequence currents
d. None of the above
Question 2: What are the factors
that affect the value of earth
electrode resistance?
a. Electrode material
b. Electrode size
c. Material and size of earth wire
d. All of the above

9. Lesson Recap
You learned the following things in this lesson:
• Introduction of earthing/grounding
• Types of earthing
• Importance of earthing