What method is known for testing ground resistance using an earth ground resistance tester?

• A. Two-point method
• B. Four-point method
• C. Three-point method
• D. Single-point method

Answer: (C)

The three-point method, also referred to as the three-terminal method, is recognized for effectively measuring ground resistance using an earth ground resistance tester. This approach involves the placement of three electrodes in the ground: one is the current electrode, and the other two serve as potential electrodes.

In this process, a known current is passed between the current electrode and the earth ground, while the voltage drop is measured between the two potential electrodes. The relationship between the current and voltage allows for the calculation of resistance using Ohm's law (R = V/I).

This method is particularly favored in practice as it reduces the influence of contact resistance and allows for more accurate readings of ground resistance. Its configuration makes it suitable for a variety of ground testing situations, ensuring that accurate measurements are obtained even in less-than-ideal conditions.