Question

Name the instrument used to measure the Earth Resistance?

Answer 1

The earth resistance is the resistance between the electrode and the point where there is zero potential. It can also be said as equal to the ratio of the potential of the earth electrode to the current dissipated by the earth.

Complete step by step solution:
Ground resistance meter is the instrument which is used for measuring the earth resistance.
The ground resistance meter generates a current and supplies this current to the measuring electrodes. The potential difference between these two electrodes provides us information about the soil resistance.
When the earth resistance is measured using an instrument, it is important to have knowledge about some basic characteristics in order to accurately measure the value of soil resistance and also, to properly size the grounding installation. The soil moisture at which this device works is another important parameter. If the metre is not able to operate at a certain level of humidity, then this particular measurement of resistance may differ from the real value of soil resistance.
Resistance of any electrode of the earth is varied by the resistivity of the surrounding soil. This depends largely on the nature of the soil. Moisture content is the most important factor. As the soil offers a resistance to the flow of the current, it cannot be considered as an ideal conductor.

Note:
The Earth Resistance measurement is carried out at only certain points along its route. The value of the Earth Resistance varies between 10 ohms to 20 ohms. Soil identifications and the programmed intensive field measurements of the soil resistivity and earthing system at some certain sites provides the proof that soil resistivity value largely depends on the type of soil.