How to Use a Multimeter to Determine Leakage Voltage and Tell a Live Wire From a Neutral Wire
How to measure the leakage voltage with a multimeter or electronic multimeter. At present, most of the enterprises and individual households use 220V AC. The central line is connected to the ground, and the protective ground line is also connected to the ground respectively. Therefore, the central line (working line) and the protective ground line are set separately, so there are two kinds of ground lines. Potential difference, so this potential difference can only be close to 36 volts, the voltage is too low to distinguish the working line and the protective ground gas as the same line. It is very dangerous to protect the ground gas because it cannot protect against electric leakage.
If the equipment casing used once leaks electricity, leakage voltage will be generated, and danger will occur if the AC voltage exceeds 36 volts.
Therefore, attention should be paid to equipment insulation and leakage.
To know and measure the leakage voltage, the method is very simple and practical, and the method is very earthy. As long as there is a multimeter (the meter head of the AC gear is from high to low), the two gauge sticks should be connected to a wet area or a water pipe with one hand, and the case should be connected to the other hand. If it exceeds 36 volts, it is a dangerous voltage.
In addition, if the other end of the high-voltage DC power supply is not directly connected to the ground, there will be no leakage voltage to the ground. But beware of touching the second-line voltage with your hands, which is also very dangerous.
It is the same principle to distinguish the live line or the working line (center line), and the test stick is connected to the wet ground or the water pipe with one hand. The other meter stick can be connected to the live wire at will, and it can be seen immediately when there is voltage.
In the simplest way, first measure the neutral wire, fire wire and ground wire, turn on the switch, switch the digital multimeter to the AC range, and switch the mechanical multimeter to ~. The voltage gear should be higher than the voltage to be measured. , one end is grounded as the sewer pipe or the indoor total zero, neither of these two places can be tied to the wall, but the tile wall is outside. At this time, the voltage level is different, because the degree of dryness and humidity of the wall is different, so the voltage will also be different. As long as tens of volts or more are read, this line is the live line. Disconnect the brake, use the multimeter with the highest resistance, the pointer type is 10K or l00K, the digital type is also the highest level, the one with the smallest reading is the ground wire, and the one with a slightly larger resistance is the zero wire. When a friend’s house was being renovated, the power transmission tripped after the completion of the work. The decorator took their electrician to find out the fault for two days, but the electrician had to find the electrician in the village. The electrician in the village did not find out the fault after several days. The socket in one place, the zero and live wires were mixed, and the socket in the mixed place was low, it was really difficult to operate, which caused the leakage device to trip.
As for the leakage, if it is a household appliance, use a 10K multimeter to measure the receiving part of the appliance. If the resistance is small, a few ohms or more than a dozen ohms, then the insulation of the appliance is damaged or aging, and there will be leakage due to moisture. Household appliances such as Do not use a megger to test TVs, computers, audio, etc., otherwise your equipment will be finished after the test is over, because the voltage of the megger is thousands of volts, which will damage electronic equipment components. If there is a leakage in the home, you can use a multimeter to measure it first. The experience is that it is almost impossible to detect when it is far away from the fault point, that is, the resistance value is very large, and sometimes it will not move. The closer to the fault point, the higher the resistance value. Small, this operation is much easier to use than shaking the watch. If the leakage is very small, you have to use a meter to measure it. In rural areas, insert an iron rod into the ground outdoors and connect a strand of wire. The upstairs is on the general location or ground, and the other side is detected by disconnection. The upper sockets are all connected in parallel, and the segmented detection and exclusion method is adopted, that is, after disconnecting from the middle house, measure in two ways, which is the simplest method for detection.
