Condition: Two ground rods are required: an auxiliary ground and a detection electrode. The distance between each ground electrode should not be less than 20 meters.
The principle is to apply a current between the auxiliary ground and the ground under test, measure the voltage drop between the ground under test and the detection electrode, and the measurement result includes the resistance of the measuring cable itself.
Applicable to: foundation grounding, construction site grounding, and lightning protection ball lightning rod QPZ grounding.
Wiring: S connects to the detection electrode, H connects to the auxiliary ground, and E and ES are connected together to the ground under test.
3. Four-wire method
Basically the same as the three-wire method, it replaces the three-wire method in low ground resistance measurements and when eliminating the influence of measuring cable resistance on measurement results. During measurement, E and ES must be separately and directly connected to the ground under test. This method has the highest accuracy among all ground resistance measurement methods.
4. Single-clamp measurement
Condition: Measure the ground resistance of each grounding point in a multi-point grounding system, and the grounding connection cannot be disconnected to prevent danger.
Applicable to: multi-point grounding, where connections cannot be disconnected, measuring the resistance of each grounding point.
Wiring: Use a current clamp to monitor the current at the grounding point under test.
