A little experience in using multimeter
1. Method of measuring leakage with multimeter
Use the on-off gear of the multimeter to measure the ground and the measured circuit part. If the meter shows resistance, it is judged that it is not insulated.
But in fact, if you measure the leakage, you should use a megohmmeter, that is, shake the meter. Because the voltage at both ends of the test pen is very low when the multimeter is measuring, generally not exceeding 9v, and the gap leakage cannot be broken down. The megohmmeter can reach more than 1000v.
Insert the multimeter connector into the terminal corresponding to the AC current measurement, then use one pen to measure the neutral or ground wire, and the other pen to measure the place where you suspect leakage, and see the multimeter indicator. If it is 0, then there is no leakage here. No voltage! If it is 220 or other voltage readings exceeding 36V, it is a leakage, indicating that it is not safe here!
Measure the insulation resistance with the 200M resistance range of the multimeter, first determine which wire is leaking, or which two wires are short-circuited.
Methods as below:
Measure the insulation resistance of the live wire and the neutral wire, measure the insulation resistance of the live wire to the ground wire, and measure the insulation resistance of the neutral wire to the ground wire. If the short circuit insulation resistance is basically zero.
Know which line is leaking, and use the segmented search method to gradually narrow down the scope of the fault.
Or use the elimination method to separate the lines and conduct power-on tests one by one.
2. How does the multimeter distinguish between the neutral wire and the live wire
Generally speaking, to identify the neutral and live wires in the mains, you must use a low-voltage tester. Can a multimeter distinguish the live and neutral wires?
The answer is yes, the method is as follows:
Turn the range switch of the multimeter to AC voltage 250V or 500V. The black test lead is connected to the indoor plumber's wet ground, land, etc., and the red test lead is in contact with the power line or power socket hole. The higher voltage value indicated by the multimeter is the live wire, and the lower or zero voltage value is the neutral wire.
3. The method of measuring the zero live wire with a digital multimeter
It is very convenient to use a multimeter to measure the neutral and live wires at home, as long as you use a digital multimeter, clamp-type multimeter, or the AC voltage range of a pointer mechanical multimeter.
The range switch of the multimeter is set to the AC voltage range (all multimeters should have this function, the range is from 200mV to 750V, generally choose the 200V range, and some clamp meters do not have a 200V range, you can choose a larger range.
The pointer multimeter gear should be smaller, you can choose 10 V 100V) and then insert the red and black test leads into V/COM (the jack for measuring the 220V voltage of household appliances at ordinary times) and wind the black test lead wire in the left hand for 2-3 turns = of course the more The more the better, pay attention: At this time, the metal needle of the black test lead must not touch your hands, in case of electric shock, then you can test, take the red test lead to test the socket or the zero live wire respectively, you write down the results of the two measurements, after that There must be a large and a small voltage between them. The large voltage measured is the live wire, and the small voltage value is of course the neutral wire. If the ground wire is sure to have no smaller voltage or even no voltage (depending on the ground wire of your home) Did you connect it!) The difference between the measured values of the voltages of the neutral wire and the live wire is clear at a glance.
