Measure and insert the grounding wire into the ground socket, thus insulating the right detection electrode of the meter (on the same side as the socket). Clip the crocodile onto your ground wire. Place the meter on the surface to be measured, press and hold the TEST button, and the continuously illuminated LED indicates the magnitude of the resistance to ground. The unit of this measurement is ohms. The conversion point of impedance value is 1/2 logarithm, which is 3.16 × 10n, the linear value of the conversion point is ± 10% of the mean value per unit of each measurement range. Measuring instrument: decade resistance box, the resistance of the testing electrode resistance box needs to be 1 × 103 ohms to 999 ohms × 106 megaohms or 109, use CAD generated techniques when measuring resistance values greater than 109, as it is difficult to verify impedance values greater than 999 using a 9-volt voltage drive × 106 resistance. Connect the two electrodes of the resistance box to the two parallel electrodes of the tester, adjust the resistance to the 1K position, and the 103 light-emitting diode (LED) of the meter should light up. The calibration of other gears should be similar. When measuring the impedance conversion point, press the switch while continuously adjusting the impedance value of the impedance bridge, and observe the impedance value of the next gear when the LED light is constantly on (the value at this time is the conversion impedance value). Main parameters Power supply: 9V PP3 alkaline battery Measurement voltage: 9V Temperature range: Working temperature 5 ° C to 49 ° C Storage temperature: -15 ° C to 60 ° C Relative humidity: 0% to 90% (non dewing state) Measurement degree: 10 Order of magnitude Transition point: 1/2 logarithm (3.16 × 10n) Transformation point accuracy: ± 1/2 level accuracy: ± 10% Repeatability: ± 5% Weight: 170 grams Size: 130 × seventy × 25 (millimeter units) Measurement accuracy: ± 0.2% Resolution: 1 μ Ω