Which test is used to measure ground resistance?

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Multiple Choice

Which test is used to measure ground resistance?

Measuring ground resistance relies on capturing how the soil itself resists current flowing from the earth electrode. The three-point Fall of Potential method is the standard way to do this. In this test, a known current is sent into the soil through one auxiliary electrode and returned via another, while the voltage between the electrode under test and a sensing probe is measured. From the measured voltage and the known current, and using the spacing geometry, you calculate the earth path resistance. This setup directly probes the earth’s resistance, separating it from wire and contact resistances, and it works well for a single grounding electrode when the probes are positioned properly. Two-point testing combines electrode and soil resistance and isn’t reliable for true ground resistance. The four-point method also measures earth resistance but is a different arrangement that can be more accurate in some soils; the question targets the three-point fall-of-potential as the classic approach. Quick check tests are only rough continuity checks, not precise resistance measurements.

Measuring ground resistance relies on capturing how the soil itself resists current flowing from the earth electrode. The three-point Fall of Potential method is the standard way to do this. In this test, a known current is sent into the soil through one auxiliary electrode and returned via another, while the voltage between the electrode under test and a sensing probe is measured. From the measured voltage and the known current, and using the spacing geometry, you calculate the earth path resistance. This setup directly probes the earth’s resistance, separating it from wire and contact resistances, and it works well for a single grounding electrode when the probes are positioned properly.

Two-point testing combines electrode and soil resistance and isn’t reliable for true ground resistance. The four-point method also measures earth resistance but is a different arrangement that can be more accurate in some soils; the question targets the three-point fall-of-potential as the classic approach. Quick check tests are only rough continuity checks, not precise resistance measurements.

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