EARTH ELECTRODE RESISTANCE MEASUREMENT
To ensure the system with good earthed and not buried within the resistance area of others electrode. Earth resistance requirements for all systems are not same, but everywhere it is required to keep less to fulfil the system requirements.
Now we are going to measure the earth electrode or grounding rod resistance measurement by Earth Tester. Previously, earth tester was totally horrible, manual or hand rotating DC generator type, receiving accurate reading was difficult. Right now lots of Digital Earth Testers are available in the market.
Measuring the Earth Electrode resistance we test actually to-
- Test the earth electrode resistance;
- Ascertain the suitability of the location of the electrode;
- Ensure that the electrode is not buried within the resistance area of another electrode.
Test Equipment Ranges:
We are using simple digital Earth Tester having Red-Yellow-Green 3 test cord; two test spikes, total Ohm range 0.01 Ω to 2000 Ω, three selector button 20 Ω, 200 Ω & 2000 Ω, power button, hold button and test button.
Earth Electrode Resistance Measurement Method:
To test or measure resistance of Grounding Rod or Earth Electrode, first of all organize the accessories as shown in figure:
- Terminal ’E’ is connected to the electrode to be tested through green conductor;
- Terminal ‘P’ is connected to the potential spike through yellow conductor at a distance of 10 meters from the earth electrode;
- Terminal ‘C’ is connected to the current spike through red conductor at a distance of 20 meters from the earth electrode.
This test must be repeated at least three times, to ensure that the readings not affected by interacting earthing regions. So, follow an example like below:
- Record the first reading Z1, say: Z1 = 1 Ω;
- Move the voltage spike to a distance of 6 meters from the original position.
- Record the second reading Z2, say: Z2 = 2 Ω;Move the voltage spike to a distance of 6 meters from the original position. Record the third reading Z3, say: Z3 = 3 Ω.
So, the resultant resistance of the earth electrode will come from the average of obtained 3 values, is (1+2+3)/3=2 Ω; so, measured earth Electrode Resistance is 2 Ω.
Now, it’s your turn to measure the earth electrode resistance by earth tester. Share your idea and comments your feelings.