How to use a multimeter to check the short circuit or ground of the line
First of all, it is necessary to separate the live wire and the neutral wire.
Ground wire: Turn the multimeter to the AC voltage range, and the range is higher than 220V. Insert the red test lead into the voltage hole, leave the black test lead unplugged, then insert the red test lead into one of the jacks of the socket and observe the reading.
If you want to check whether there is a short circuit in the line. First, the line should be powered off, then the load switches should be opened, and the resistance between the two lines should be blocked by the ohm of the multimeter. Normally, the larger the resistance, the better. If you determine whether the line is grounded, you can use the ohm block of the multimeter. to measure the resistance of each line to ground. Also bigger is better. It should be pointed out that it is inaccurate to use a multimeter to measure whether there is a short circuit and grounding in the line. It should not be, if the grounding or short-circuit resistance is very small, it can be detected with a multimeter, if the resistance is slightly larger. The multimeter cannot be checked, it is in the low voltage loop of 380V. Should be measured with a 500V shaker, whether between lines or to ground. Both should be above 0.38 megohms. Otherwise it is unqualified.
The largest reading is the live wire, the smaller reading is the zero wire, and the one with basically no movement is the ground wire.
If there are two low readings and one reading is large, it means that the ground wire is not grounded, and the ground wire is also connected to the neutral wire. The second step after that does not need to be measured.
Turn the multimeter to the "short circuit" test function, (if there is no resistance test), the red and black test leads are respectively connected to the ground of the circuit and the ground of the mains. If the test result is a short circuit or the resistance is extremely small, the line is grounded , and vice versa.
Check for leakage and grounding, and turn the multimeter to 200M. For example, measuring equipment insulation, connect one end of the test lead to the device shell or ground wire, and the other end of the test lead to the line. When measuring insulation, hands should not touch the test leads to prevent measurement errors.
Adjust the resistance gear of the multimeter to 20K or 200K, turn off the main power supply and the load power supply, use a multimeter to connect one test lead to the live wire, one test lead to the ground wire, check the resistance value, then one test lead to the neutral wire, and one test lead to the ground wire, watch In the case of two resistance values, if there is a resistance above 7.3, or above 14., it means that the live wire or neutral wire connected to the resistance value is leaking.
