Method for Detecting Leakage Faults in Lighting Circuits with a Multimeter
1, The insulation of wires or equipment is damaged by external forces;
2, The long-term operation of the line has led to insulation aging and deterioration;
3, The insulation of the circuit is poor due to moisture invasion or contamination.
The maintenance of leakage faults first determines whether there is indeed leakage. The insulation resistance of the measuring circuit can be measured using a pointer type R × 10k gear, or a digital multimeter can be placed in the AC current gear, which is equivalent to an ammeter. It is connected in series to the main switch, all switches are turned on, and all loads including light bulbs are removed. If there is current, it indicates the presence of leakage. After determining the leakage of the circuit, the following steps can be followed to continue the inspection.
1. Determine whether there is leakage between the phase line and the neutral line, leakage between the phase line and the ground, or a combination of both.
The method is to cut off the neutral line. If the ammeter reading remains unchanged, it is a leakage between the phase line and the ground; If the ammeter indicates zero, it is a leakage between the phase line and the neutral line; If the ammeter reading decreases but is not zero, it means that there is leakage between the phase line and the neutral line, as well as between the phase line and the ground.
2. Determine the range of leakage.
Remove the shunt fuse or pull it open. If the ammeter reading remains unchanged, it indicates bus leakage; If the ammeter indicates zero, it is a branch leakage; If the ammeter reading decreases but is not zero, it indicates that there is leakage in both the bus and branch circuits.
3. Find the leakage point.
After the above inspection, disconnect the switches of the lighting fixtures on the circuit in sequence. When a certain switch is disconnected, the ammeter indicates zero, indicating that the branch line is leaking electricity; If it becomes smaller, it indicates that there is leakage in other areas besides this branch line; If the ammeter reading remains unchanged after all lamp switches are turned off, it indicates that the main line is leaking electricity. By narrowing down the scope of the accident in sequence, further inspection can be conducted to determine if there is any leakage at the joints of the line and at the locations where the wires pass through the wall. After finding the leakage point, the leakage fault should be eliminated in a timely manner.
