How to measure leakage current with multimeter
When measuring resistance with a multimeter, use a multimeter to measure diodes, and the black stylus is connected to the power supply in the meter. How to measure leakage current with a multimeter?
It is not a good method to use multimeter to measure whether there is leakage in 220 volt lines, because there will be a big error in multimeter measurement. The minimum current that the human body can perceive is 1 mA; The leakage current of about 5~7 mA can make the finger muscles feel cramped; Leakage of more than 10 mA will cause pain and burning sensation to fingers and palms; When it exceeds 30 mA, you can't get rid of the power independently, and your breathing begins to be paralyzed. It can't be accurately detected by multimeter, which easily leads to the illusion that there is no leakage, and the danger continues.
The method of judging leakage by multimeter is to measure resistance, but because the power supply of multimeter is only 9 volts, there will be a big error when measuring large resistance. After disconnecting the main line brake and all electrical loads, the resistance value of the live zero line can be measured, and the resistance value should be infinite, but this method can only be roughly estimated and cannot be used as an accurate judgment. But when measured with a shaking table, the resistance value is greater than 1mω, which can be considered as good insulation.
Using multimeter to measure leakage is far worse than using leakage protector to judge. Select a leakage protector with action current of 6 mA to connect to the bus. If the reset button pops up after tripping, it can be judged that there is leakage in the line. According to this method, the leakage protector is connected to each branch and checked step by step, and finally the leakage position can be determined. Why choose the leakage protector with action current of 6 mA for inspection? Because the leakage current less than 6 mA will not pose a threat to human body, the electric meter will not measure it.
To sum up, it is best to use a professional megger (shaking table) to measure the insulation resistance of the line in order to judge the leakage most accurately, and a multimeter can be used for the preliminary judgment. At the same time, it is strongly not recommended to repair the line with live measurement. Most electric shock accidents are caused by live maintenance, so don't try live maintenance unless you have to.
