What is Earthing?
In earthing, all equipment non-current carrying parts like equipment body etc connected to the earth electrode through the earth wire or earth strip is called earthing. By earthing body of the equipment is brought to zero potential with respect to the earth.
When the fault occurs in the equipment, the potential at the non-current parts of the equipment body raises and when the human or animal touches this equipment body, then they may get shocked and cause an accident.
The earthing discharge the leakage current from the non-current-carrying body of equipment to earth and safeguard the life of humans and animals. The earthing also discharge the heavy lightning stroke to the earth and protect the equipment from damage.
Needs of electrical earthing
1. The electrical earthing protects humans and animals from electrical shock.
2. The earthing provides the low resistance path to the fault currents during the fault and if the insulation of the equipment fails.
3. The electrical earthing protects all the costly equipment from the high voltage switching surges and lightning strokes.
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| Difference Between Grounding and Earthing |
What is Grounding?
In grounding, current-carrying parts of all the equipment are connected to the earth electrode through the earth wire. The grounding provides the return path to fault current and protects our power system's costly equipment from damage.
When the fault occurs in the power system equipment, the current of the three phases of the equipment becomes unbalanced and fault current or unbalanced current is discharged by the grounding earth. so the current of all three phases become balanced.
The grounding is employed in electronic devices and high voltage substations. The static electricity is produced in electronic equipment. Disturbances are caused in the operation of the equipment due to the accumulation of charges on the metal parts. due to grounding the static charges are given path and grounded parts come to the same potential. this is called the grounding.
Some benefits of grounding are
1. Grounding eliminates the effect of surge voltage and it is discharged to the earth.
2. The grounding discharged overvoltage to the ground.
3. The grounding provides better safety to equipment and provides better service reliability.
Comparison table between the grounding and earthing
| Grounding | Earthing |
|---|---|
| In grounding, current-carrying parts of the equipment are connected to the earth | In earthing, non-current carrying parts of the equipment are connected to the earth. |
| The grounding is used for load balancing of the power system during the fault | earthing is used for protection from electrical shock hazards. |
| The grounding is located between the neutral of the equipment and the earth. | The earthing is located between the equipment body and the earth. |
| The grounding protects the whole power system from malfunctioning due to unbalance phase current due to fault in the equipment. | The earthing protects human life from shock. |
| The grounding does not have any zero potential. | The earthing contains zero potential. |
| The grounding provides the return path to the current. | The earthing discharge the electrical current to the earth. |
| There are three types of grounding methods are used such as solid, resistance and reactance grounding. | There are five methods are used for earthing such as pipe, plate, rod, earthing through tap and strip earthing. |
| In grounding colour of the wire is black. | In earthing colour of the wire is green. |
| The grounding is used for balancing the unbalanced load due to fault. | The earthing is used for avoiding electrical shock hazards. |
| The example of grounding is neutral of generator and power transformers which are connected to the ground. | The encloser of induction motor. power transformer, the generator is connected to the earth which is an example of earthing. |
| The grounding is a backup pathway | earthing is a preventive measure. |
| In grounding fuse or earth fault relay not operated during the fault. | In earthing, fuse or earth fault relay are operated during the fault. |
| In grounding, It is not necessary to have a greater area of cross-section of the grounding wire as it is used to bring the connected parts to the same potential. | In Earthing, the cross-section for the earthing conductor should be more as the short circuit current flows when a fault occurs. |
Comparison between the grounding and earthing
1. In grounding, current-carrying parts of the equipment are connected to the earth and In earthing, non-current carrying parts of the equipment are connected to the earth.
2. The grounding is used for load balancing of the power system during the fault and earthing is used for protection from electrical shock hazards.
3. The grounding is located between the neutral of the equipment and the earth. The earthing is located between the equipment body and the earth.
4. The grounding protects the whole power system from malfunctioning due to unbalance phase current due to fault in the equipment. The earthing protects human life from shock.
5. The grounding does not have any zero potential. The earthing contains zero potential.
6. The grounding provides the return path to the current. The earthing discharge the electrical current to the earth.
7. There are three types of grounding methods are used such as solid, resistance and reactance grounding. There are five methods are used for earthing such as pipe, plate, rod, earthing through tap and strip earthing.
8. In grounding colour of the wire is black. In earthing colour of the wire is green.
9. The grounding is used for balancing the unbalanced load due to fault. The earthing is used for avoiding electrical shock hazards.
10. The example of grounding is neutral of generator and power transformers which are connected to the ground. The encloser of induction motor. power transformer, the generator is connected to the earth which is an example of earthing.
11. The grounding is a backup pathway and earthing is a preventive measure.
12. In grounding fuse or earth fault relay not operated during the fault. In earthing, fuse or earth fault relay are operated during the fault.
13. In grounding, It is not necessary to have a greater area of cross-section of the grounding wire as it is used to bring the connected parts to the same potential. In Earthing, the cross-section for the earthing conductor should be more as the short circuit current flows when a fault occurs.
Important notes
1. The resistance of earth wire should be less than 1 ohms.
2. The size of earthing wire should be half of the phase wires.
3. The copper wire is used for grounding and eating purposes.
4. In grounding and earthing the parts are brought to equal potential.
5. The conductor is required in both systems.
6. The electrode used for earthing should be in a verticle position so more connectivity with the earth is possible.
7. The material used for making the earth electrode and material used for the wiring should be the same.