Earthing,Grounding and Bonding

1. GROUNDING/EARTHING
AND BONDING
Presented by:
Muhammad Faizan Saleem
Ali Raza
Presentedto:
Engineering Department
Solutions Engineering (Pvt.) Ltd
Presentation #1
31/12/2015
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2. Contents
 Earthing/Grounding
 Bonding
 Methods of Earthing/Grounding
 Advantages
 Disadvantages
 Applications
 Conclusions
 References
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3. Grounding/Earthing
The process of connecting the metallic frame (i.e. non-
current carrying part) of electrical equipment or some
electrical part of the system to earth (i.e. soil) is called
grounding or earthing.
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4. Need of Earthing or
Grounding
 Protection of human lives.
 Safety of electric system and buildings.
 To avoid the risk of fire in electrical installation
systems.
 To keep voltage as constant in healthy phase
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5. Types of Grounding
 Equipment Grounding
The process of connecting non-current-carrying metal
parts (i.e. metallic enclosure) of the electrical equipment to
earth (i.e. soil) in such a way that in case of insulation
failure, the enclosure effectively remains at earth potential
is called equipment grounding.
 System Grounding
The process of connecting some electrical part of the
power system to earth (i.e. soil) is called system
grounding.
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6. Equipment Grounding
Ungrounded Enclosure
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7. Continue..
 Enclosure connected to neutral wire
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8. Continue..
 Ground wire connected to enclosure
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9. System Grounding
 Fig shows the primary winding of a distribution transformer
connected between the line and neutral of a 11 kV line. If the
secondary conductors are ungrounded, it would appear that a person
could touch either secondary conductor without harm because there
is no ground return However, this is not true.
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10. Ungrounded & Grounded
System
 Let us now turn to a more serious situation. The
secondary conductors are ungrounded.
 Suppose that the high voltage line touches the low
voltage conductor.
 This would immediately puncture the 230 V insulation,
causing a massive flashover.
 Therefore, ungrounded secondary in this case is a
potential fire hazard and may produce grave accidents
under abnormal conditions.
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11. Continue..
 If one of the secondary lines is grounded as shown in Fig.
below, the accidental contact between a 11 kV conductor
and a 230 V conductor produces a dead short. The short-
circuit current (i.e. fault current) follows the dotted path
shown in Fig.
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12. Bonding
 Bonding is simply the act of joining two electrical
conductors together. Bonding provides a means for various
wiring fixtures to interconnect with the grounding system.
 Provide a safer and more effective path to ground.
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13. Earth Resistance Testing
Methods
 Three and Four pin method:
i. Equipment (Earth tester, Spikes,
Earthing Electrode, Measuring tape).
ii. Spikes distance(25m)
iii. Spike length in earth(1/20 of spike
distance)
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14. Three Pin Method
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15. Four Pin Method
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16. Methods of Earthing
 Plate Earthing
 Pipe Earthing
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17. Plate Earthing
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 Copper plate of 60cm x 60cm x 3.18cm or a GI
plate of the size 60cm x 60cm x 6.35cm is used
for earthing.
 The plate is placed vertically down inside the
ground at a depth of 3m and is embedded in
alternate layers of coal and salt for a thickness
of 15 cm.
 Water is poured for keeping the earth electrode
resistance value well below a maximum of 5
ohms. The earth wire is securely bolted to the
earth plate.

18. Plate Earthing
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19. Pipe Earthing
 Earth electrode made of a GI (galvanized) iron
pipe of 38mm in diameter and length of 2m.
 To keep the value of the earth resistance at the
desired level, the area (15 cms) surrounding the
GI pipe is filled with a mixture of salt and coal.
 The efficiency of the earthing system is
improved by pouring water through the funnel
periodically.
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20. Pipe Earthing
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21. Advantages
 Protect personnel.
 Protect equipment.
 It is required by electrical codes.
 It is required by equipment
manufactures.
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22. Disadvantages
 Cost: The provision of complete
system of protective conductor, earth
electrodes etc is very expensive.
 Possible Safety hazards.
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23. Applications
 Equipment Earth: Path for fault currents, lower
touch voltage, protection against electric shock.
 Lighting Earth: Low resistance path to diverse
current under lightning attack.
 Telecom Earth: Signal earth, reduce noise and
interference, stabilize dc power supply voltage.
 Computer Earth: Reduce interference, maintain
supply voltage.
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24. Conclusion
 We have stressed the importance of
earthing/grounding.
 Poor grounding can lead to death.
 On the other hand, there are some clear cut
occasions where a floating (non-grounded)
architecture is not only easier, but much better
for the safety of both man and machine.
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25. References
 http://electrical-engineering-portal.com/what-is-the-difference-
between-bonding-grounding-and-earthing
 http://elearning.vtu.ac.in/e-con/EEE/html/0032.htm
 https://electricalnotes.wordpress.com/2011/11/27/what-is-earthing/
 file:///C:/Users/lab/Downloads/2005_16_autumn_wiring_matters_ear
thing_your_questions_answered.pdf
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