For the measurement of the earth resistance of a given earth electrode
Right Answer is:
Collecting electrode should be far way the electrode under test
When performing a measurement, the aim is to position the auxiliary test electrode C far away from the earth electrode under test so that the auxiliary test electrode P will lie outside the effective resistance areas of both the earth system and the other test electrode.
- If the current test electrode, C, is too close, the resistance areas will overlap and there will be a steep variation in the measured resistance as the voltage test electrode is moved.
- If the current test electrode is correctly positioned, there will be a ‘flat’ (or very nearly so) resistance area somewhere in between it and the earth system, and variations in the position of the voltage test electrode should only produce very minor changes in the resistance.