1. Before measuring, keep the megohmmeter in a horizontal position, press the body of the meter with your left hand, and shake the rocker of the megohmmeter with your right hand, the speed is about 120r/min, and the pointer should point to infinity (∞), otherwise the megohmmeter is malfunctioning.

2. Before measurement, cut off the power supply of the electrical appliance and circuit under test, and perform temporary grounding and discharge of related components to ensure the safety of the person and the megohmmeter and the accuracy of the measurement results.

3. The wiring must be correct during measurement. The megohmmeter has 3 terminals (L, E, G). When measuring the loop resistance to ground, connect the L terminal to the exposed conductor of the loop, and connect the E terminal to the ground wire or metal shell; when measuring the insulation resistance of the loop, connect the head and tail ends of the loop to L and E respectively; measure the insulation of the cable For resistance, in order to prevent the leakage current on the cable surface from affecting the measurement accuracy, the shielding layer of the cable should be connected to the G terminal.

4. The measurement cord from the megohmmeter terminal should be well insulated, and a proper distance should be kept between the two wires and between the wire and the ground, so as not to affect the measurement accuracy.

5. When shaking the megohmmeter, do not touch the terminal of the megohmmeter and the circuit under test with your hands to prevent electric shock.

6. After shaking the megohmmeter, the terminals should not be short-circuited to avoid damage.