How to measure the leakage current with a multimeter
It is not a good method to use a multimeter to measure whether there is leakage in a 220-volt line, because the multimeter measurement will have relatively large errors. The minimum current that the human body can perceive is 1 milliampere; a leakage current of about 5-7 milliamperes can make the finger muscles feel convulsive; a leakage current of more than 10 milliamperes will cause pain and burning sensation to the fingers and palms; When the mA is above, it is impossible to get rid of the power supply independently, and the breathing becomes paralyzed. It cannot be accurately detected by a multimeter, and it is easy to cause the illusion that there is no leakage, and the danger continues to exist.
The way to use a multimeter to judge the leakage is to measure the resistance, but since the power supply of the multimeter is only 9 volts, a relatively large error will occur when measuring a large resistance. After disconnecting the main circuit breaker and disconnecting all electrical loads, you can measure the resistance value of the live wire and the neutral wire. The resistance value should be infinite, but this method can only be roughly estimated and cannot be used as an accurate judgment. Instead, when measuring with a megger, if the resistance value is greater than 1MΩ, it can be considered that the insulation is good.
Using a multimeter to measure leakage is far worse than using a leakage protector to judge. Select a leakage protector with an operating 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, connect the leakage protector to each branch and check step by step, and finally the location of the leakage can be determined. Why choose a leakage protector inspection with an operating current of 6 mA? Because the leakage current less than 6 mA will not pose a threat to the human body, the meter will not measure it.
To sum up, it is best to use a professional megohmmeter (shake meter) to measure the insulation resistance of the line to judge the leakage, so that the judgment is the most accurate, and the multimeter can be used for the preliminary judgment. At the same time, live measurement and maintenance lines are strongly not recommended. Most electric shock accidents are caused by live maintenance. Do not attempt live maintenance unless it is absolutely necessary.
