How to Measure Leakage Voltage and Distinguish between Live and Zero Lines with a Multimeter

How to Measure Leakage Voltage and Distinguish between Live and Zero Lines with a Multimeter

How to measure leakage voltage using a multimeter or electronic multimeter. Currently, most of the electricity used by enterprises and households is 220V AC. The central line is connected to the ground, and the protective ground wire is also connected to the ground separately. Therefore, the central line (working line) and the protective ground wire are set separately. Therefore, there is also a potential difference between the two types of ground wires, so 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 as the same line. It is very dangerous to protect the earth's atmosphere without providing leakage protection.

If the casing of the equipment used leaks electricity, it will generate leakage voltage, and exceeding 36 volts AC voltage will cause danger.

Therefore, attention should be paid to equipment insulation and leakage in general.

To know and measure the leakage voltage situation, the method is very simple and practical, and the method is very rustic. As long as there is a multimeter (AC range meter head from high to low), two meter rods are connected to the damp wetland section or water pipe with one hand, and the other hand is connected to the machine casing. If the voltage exceeds 36 volts, it is considered a dangerous voltage.

Also, for high-voltage DC power sources that do not directly connect to the ground at the other end, there will be no leakage voltage to the ground. But be careful when your hands come into contact with the second line voltage, which is also very dangerous.

The same principle is used to distinguish between a hot line or a work line (centerline), where a watch stick is placed on a damp wetland or water pipe with one hand. Another watch rod can be easily connected to a live wire, and the voltage can be immediately distinguished.

Using the simplest method, measure the zero wire, live wire, and ground wire, close the switch, set the digital multimeter to the AC position, and set the mechanical multimeter to the~position. The voltage position should be higher than the measured voltage, for example, when measuring 220V, set 500V or 750V, and connect one end to the ground, such as a sewer pipe or indoor total zero. Neither of these places can be tied to the wall, but the side outside of the ceramic tile wall is acceptable. At this point, the voltage varies, as the dryness and wetness of the wall vary, so the voltage will also vary. As long as a few tens of volts or more are read, this wire is a live wire. Disconnect the switch and use a multimeter to measure the maximum resistance, with a pointer type of 10K or 100K. The digital value is also the highest. The wire with the lowest reading is the ground wire, and the wire with a slightly higher resistance value is the zero wire. When a friend's home was being renovated, the power supply tripped after completion. The decorator took their electrician for two days and couldn't find the fault. The electrician had to contact the village electrician. The village electrician worked for several days but couldn't find the problem. Later, it was found that the sockets and zero wires in several places were mixed, and the sockets in the mixed areas were low, which was really difficult to operate, which led to the leakage device tripping.

As for leakage, if it is a household appliance, use a multimeter with a 10K range to measure the receiving part of the appliance. If the resistance measurement is very small, a few or more ohms, the insulation of the appliance will be damaged or aged, and there will be leakage due to dampness. Household appliances such as televisions, computers, audio systems, etc. should not be tested with a megger. Otherwise, if the test is completed, your device will also play, because the voltage of the megger is over kilovolts, which can damage electronic device components. If there is a leakage in the indoor area of the home, you can first use a multimeter to measure the resistance. Experience has shown that it is almost impossible to measure when far away from the fault point, which means that the resistance value is very high and sometimes does not move. The closer you are to the fault point, the smaller the resistance value. This operation is actually much easier to use than shaking the meter. If the leakage situation is very small, a megger should be used to measure it. In rural areas, an underground iron rod should be inserted outdoors and a strand of wire should be connected. The upper floor should be connected to the main location or ground wire, and the other side should be tested using the disconnection method. As the sockets on the upper floor are all connected in parallel, the segmented detection and elimination method should be adopted, that is, after disconnecting from the middle room, the measurement should be divided into two paths. This is the simplest method of detection.