Condition: There must be a known good grounding point, such as PEN, etc. The measured result is the sum of the resistance of the tested ground and the known ground. If the known ground resistance is much smaller than that of the tested ground, the measurement result can be taken as the resistance of the tested ground.
Applicable to: Areas with dense buildings or sealed concrete ground where ground rods cannot be driven.
Wiring: Connect E+ES to the tested ground, and H+S to the known ground.
2. Three-Point Method
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 current between the auxiliary ground and the tested ground, measure the voltage drop between the tested ground 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 spherical lightning rod QPZ grounding.
Wiring: Connect S to the detection electrode, H to the auxiliary ground, and connect E and ES together to the tested ground.
3. Four-Point Method
Basically the same as the three-point method, but used to replace the three-point method in low ground resistance measurements and to eliminate the influence of measuring cable resistance on measurement results. During measurement, E and ES must be separately and directly connected to the tested ground. 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 without disconnecting the grounding connection to prevent danger.
Applicable to: Multi-point grounding, where connections cannot be disconnected, to measure the resistance of each grounding point.
Wiring: Use a current clamp to monitor the current at the tested grounding point.
5. Dual-Clamp Method
Condition: Multi-point grounding, without driving auxiliary ground rods, to measure a single ground.
Wiring: Use the current clamp specified by the manufacturer and connect it to the corresponding socket. Clamp the two clamps onto the grounding conductor, with a distance between the two clamps greater than 0.25 meters.
Ground Resistance Tester Product Recommendations
