Pointer multimeter distinguishes phase line and neutral line
1. Contact measurement method
Put the multimeter switch on the AC 250V or 500V gear, connect the first test lead to one end of the power supply, and the second test lead to the ground (such as water pipes, radiators, etc. or wet ground). If the grounding is good, when the reading of the multimeter is about 220V, the first test lead is connected to the phase line of the power supply. If the pointer does not move, it means that the first test lead is connected to the neutral line of the power supply. Even if the grounding resistance of the second test lead is large, when the first test lead is connected to the phase line, the pointer will have obvious deflection.
2. Non-contact measurement method
Put the switch of the multimeter in the AC 250V or 500V gear, connect the first test lead to either end of the power supply, place the second test lead in the air on the table, and hold the insulating rod part of the second test lead with your hand (be careful not to touch it with your hands) conductive parts). If the first test lead is connected to the phase line, the pointer of the meter head can generally be deflected by 2 to 10 divisions. The higher the sensitivity of the multimeter, the more obvious the deflection. If the first test lead is connected to the zero line, the pointer of the meter head will not deflect.
This method works with any model of multimeter. This method will not cause danger to the human body. Because the internal resistance of the pointer multimeter is 20K/V, if it is used to measure 220V voltage, the internal resistance of the pointer multimeter is 20K×220V=4400, which is relatively safe.
3. Precautions
It is best to use a test pen to distinguish the phase line and neutral line of the mains, which is a fast and safe method.
Be sure to pay attention to safety when using a pointer multimeter to distinguish the phase line and the neutral line. Specifically, the insulation of the test lead line should be good, and the operator's hands and any part of the body cannot directly contact the metal part of the test lead to avoid the risk of electric shock.
