Earthing and Grounding Practices — MCQs – EE

1. The main purpose of earthing in electrical systems is to:
(A) Ensure safety of personnel and equipment
(B) Increase voltage
(C) Improve insulation resistance
(D) Reduce current flow

2. Earthing provides a path for:
(A) Fault current to flow safely to the ground
(B) Load current to return
(C) Circuit breaker tripping
(D) Neutral balancing

3. The term “earthing” is commonly used in:
(A) United Kingdom and Commonwealth countries
(B) United States
(C) Japan only
(D) Germany

4. The term “grounding” is commonly used in:
(A) United States
(B) India
(C) Australia
(D) United Kingdom

5. In electrical installations, the earthing system connects:
(A) Non-current carrying parts of equipment to earth
(B) Current carrying conductors together
(C) Neutral and phase conductors
(D) Transformer windings

6. The main objective of equipment earthing is to:
(A) Protect human life from electric shock
(B) Increase current capacity
(C) Improve voltage regulation
(D) Reduce load

7. System earthing is provided to:
(A) Stabilize system voltage under fault conditions
(B) Increase frequency
(C) Improve load balancing
(D) Reduce power losses

8. The most commonly used earthing system in domestic installations is:
(A) TT system
(B) IT system
(C) TN-S system
(D) TN-C system

9. In a TN-S system, the neutral and protective earth conductors are:
(A) Separate throughout the system
(B) Combined throughout the system
(C) Combined at all points
(D) Not connected at all

10. In a TN-C system, the neutral and protective conductors are:
(A) Combined into a single conductor (PEN)
(B) Separated from each other
(C) Used for control signals
(D) Not used in low-voltage systems

11. The resistance of an effective earth electrode should be:
(A) As low as possible
(B) Very high
(C) Constant at all times
(D) Equal to load resistance

12. The typical value of good earthing resistance for domestic installations is:
(A) Less than 5 ohms
(B) 10 to 20 ohms
(C) Above 50 ohms
(D) Exactly 100 ohms

13. The most common type of earthing electrode used in practice is:
(A) Pipe or rod electrode
(B) Plate made of plastic
(C) Wooden stick
(D) Ceramic rod

14. The plate earthing method uses:
(A) Copper or galvanized iron plate buried in the earth
(B) Aluminum foil
(C) Steel mesh
(D) Carbon plate

15. In pipe earthing, the pipe is usually made of:
(A) Galvanized iron
(B) Plastic
(C) Aluminum
(D) Copper oxide

16. The depth of burial of a pipe earthing electrode is usually:
(A) 2.5 to 3 meters below ground level
(B) 0.5 meter
(C) 10 meters
(D) 0.1 meter

17. The earth resistance depends on:
(A) Soil resistivity and moisture content
(B) Supply frequency only
(C) Transformer capacity
(D) Type of load connected

18. Moisture in the soil helps to:
(A) Decrease earth resistance
(B) Increase resistance
(C) Maintain high voltage
(D) Break insulation

19. Adding common salt around an earth electrode helps to:
(A) Reduce soil resistivity
(B) Increase thermal conductivity
(C) Increase current
(D) Reduce electrode corrosion

20. Earth mats are used for:
(A) Substation earthing systems
(B) Domestic earthing only
(C) Insulating cables
(D) Underground cable joints

21. The material commonly used for an earthing conductor is:
(A) Copper or galvanized iron
(B) Plastic
(C) Aluminum alloy
(D) Steel coated with paint

22. The neutral of a transformer is generally:
(A) Solidly earthed or through resistance
(B) Left floating
(C) Connected to the phase
(D) Connected through a capacitor

23. High resistance grounding is used in:
(A) Industrial systems to limit fault current
(B) Domestic systems
(C) DC distribution
(D) Transmission lines only

24. Earthing helps in:
(A) Protecting equipment from lightning and surge voltages
(B) Increasing system frequency
(C) Power factor improvement
(D) Reducing power generation

25. Step potential refers to:
(A) Voltage difference between two points on the ground separated by a step
(B) Voltage across circuit breaker contacts
(C) Neutral potential rise
(D) Voltage across insulation

26. Touch potential is:
(A) The voltage between a grounded metallic structure and a point on the ground
(B) Voltage between two phase conductors
(C) Voltage between phase and neutral
(D) Potential difference between two earth pits

27. Earthing conductors in substations are usually sized based on:
(A) Fault current and duration
(B) Load current
(C) Cable size
(D) Voltage level only

28. The resistance of an earthing system can be measured by:
(A) Earth tester or megger
(B) Voltmeter only
(C) Ammeter
(D) Multimeter on resistance mode

29. The function of a lightning arrester is to:
(A) Discharge surge voltages to earth
(B) Block current flow
(C) Isolate the circuit
(D) Increase voltage

30. The overall purpose of proper earthing and grounding is to:
(A) Protect people and equipment, and ensure system stability
(B) Increase load capacity
(C) Reduce transformer losses
(D) Enhance voltage drop