How to use a multimeter to detect the leakage fault of the lighting circuit
Once leakage occurs in the lighting circuit, it will not only waste electric energy, but also may cause electric shock accidents. The essence of leakage and short circuit is the same, but the degree of accident development is different. Severe leakage may cause short circuit. Therefore, the leakage of lighting lines must not be taken lightly. The insulation of the line should be checked frequently, especially when leakage is found, the cause should be found out in time, the fault point should be found, and it should be eliminated.
The main reasons for the leakage of lighting lines are: first, the insulation of wires or electrical equipment is damaged by external force; second, the long-term operation of the line leads to aging and deterioration of the insulation;
First, determine whether there is indeed a leakage. Use the R×10k range of the pointer multimeter to measure the insulation resistance, or place the digital multimeter in the AC current range (equivalent to an ammeter at this time), connect it in series to the main switch, turn on all the switches, and remove all loads (including Light bulb). If there is current, it means that there is leakage. After confirming the leakage of the line, you can continue to check according to the following steps.
1. Determine whether it is the leakage between the phase line and the neutral line, or the leakage between the phase line and the earth, or both. The method is to cut off the neutral line. If the ammeter indication remains unchanged, it is the leakage between the phase line and the earth; if the ammeter indication is zero, it is the leakage between the phase line and the neutral line; Leakage between line, phase line and earth.
2. Determine the leakage range. Take off the shunt fuse or pull open the circuit breaker. If the ammeter indication remains unchanged, it means the bus leakage; if the ammeter indication is zero, it is the shunt leakage; All have leakage.
3. Find the leakage point. After the above inspection, turn off the switch of the line lamp in turn. When a switch is turned off, the ammeter indicator returns to zero, and the branch line is leaking; if it becomes smaller, it means that there is leakage in other places besides the branch line; If the ammeter indication remains unchanged after all the lamp switches are turned off, it means that this section of the main line is leaking. By narrowing down the scope of the accident in turn, you can further check whether there is leakage at the joints of the line and where the wires pass through the wall. After finding the leakage point, the leakage fault should be eliminated in time. The load end starts to detect step by step towards the front end, and it can be judged by checking whether the work is caused by the line or the component. After eliminating the short-circuit fault point, install a qualified fuse and then send power.
Short circuit, open circuit and leakage of lighting circuit are the most common faults. Only by carrying out specific measurement and analysis can we accurately find out the fault point, determine the nature of the fault, and take effective measures to eliminate the fault as soon as possible.
