How to measure leakage voltage and differentiate between live and neutral wires using a multimeter
How to measure leakage voltage with a multimeter or electronic multimeter. Nowadays, most of the electricity used by enterprises and households is 220 volt AC power. The center line is grounded, and the protective ground wire is also connected to the ground separately. Therefore, the center line (working line) and the protective ground wire are set separately, and there is also a potential difference between the two types of ground wires. Therefore, this potential difference can only be close to 36 volts. If the voltage is too low, it is difficult to distinguish between the working line and the protective ground wire, which are considered to be the same wire. Protecting the earth's atmosphere cannot provide leakage protection, which is very dangerous.
If the casing of the device used leaks electricity, it will generate leakage voltage, which can cause danger if the AC voltage exceeds 36 volts.
To know and measure the leakage voltage situation, the method is simple and practical, and the method is very rudimentary. As long as there is a multimeter (AC gear head from high to low), with two meter rods, one hand is placed on the wet section or water pipe, and the other hand is placed on the machine casing. If the voltage exceeds 36 volts, it is considered a dangerous voltage.
Additionally, it should be noted that for high-voltage direct current power sources that are not directly grounded at the other end, there will be no leakage voltage to the ground. But be careful not to touch the second line voltage with both hands, which is also very dangerous.
The simplest way is to measure the neutral wire, live wire, and ground wire, close the switch, set the digital multimeter to AC mode, and set the mechanical multimeter to~. The voltage level should be higher than the measured voltage, for example, when measuring 220 volts, set it to 500 volts or 750 volts. One end should be grounded, such as in a sewer pipe or indoor main zero. Neither of these places can be tied to the wall, but on the outside of the tile wall side. At this time, the voltage varies because the dryness and wetness of the walls are different, so the voltage will also be different. As long as it reads a few tens of volts or more, this wire is a live wire. Disconnect the circuit breaker and use a multimeter to measure the maximum resistance. The pointer type is 10K or 100k, and the digital type is also the highest gear. The wire with the smallest reading is the ground wire, and the wire with a slightly higher resistance is the neutral wire. During the renovation of a friend's house, the power supply tripped after completion. The renovation workers searched for their electrician for two days but couldn't find the fault. The electrician had to turn to the electrician in the village, who worked for several days but couldn't find any problems. Later, it was discovered that several sockets had mixed neutral and live wires, and the sockets in the mixed areas were low, making it difficult to operate, which led to the leakage of electrical appliances and tripping.
As for electrical leakage, if it is a household appliance, use a multimeter with 10K range to test the receiving part of the appliance. If the resistance is measured to be very small, a few ohms or more, the insulation of the appliance will be damaged or aged, and there will be leakage due to moisture and dampness. Household appliances such as televisions, computers, speakers, etc. should not be tested with a shaking meter, otherwise your device will also run out because the shaking meter voltage is over kilovolts, which can damage electronic components. If there is a leakage point indoors, you can first use a multimeter to measure the resistance range. Experience shows that it is almost impossible to measure when far away from the fault point, that is, the resistance value is very high and sometimes it does not move. The closer to the fault point, the smaller the resistance value. This operation is actually much more useful than shaking the meter. If the leakage situation is very small, a shaking table needs to be used for measurement. In rural areas, an underground iron rod is inserted and a wire is connected. On the other side, the disconnection method is used for detection. Since the sockets on the upper floor are all connected in parallel, the segmented detection and elimination method is adopted, that is, after disconnecting from the middle room, the measurement is divided into two paths. This is the simplest method of detection.
