How to use a multimeter to test the quality of the grounding wire of the socket at home
multimeter test
Adjust the multimeter to 250V~ or the AC voltage range closest to and greater than 220V, and measure the voltage between the live wire and the neutral wire, and the live wire and the ground wire respectively.
If the difference between the two sets of voltages is less than 5V, it proves that the ground wire is well grounded—and the smaller the difference, the better the grounding quality.
light bulb test
Take a light bulb, connect one end to the live line, and the other end to the neutral line and the ground line respectively, and compare the brightness of the two bulbs.
If the brightness is the same twice, or the bulb is slightly dim when connected to the ground wire, the ground wire is well grounded; if the bulb does not light up when connected to the ground wire, the ground wire is faulty.
Note: When testing with this method, there should be no leakage switch in the line, otherwise the leakage switch will trip when testing the ground wire, and the comparison cannot be made.
phase detector
This thing is cheaper than a multimeter, about 10 yuan, many brands have it, and ordinary users should always have it in their families.
It is also very convenient to use, directly plug it into the socket, observe the order of the three lights on the detector, and compare the examples, you can know whether the ground wire is normal (the fault of the zero live wire can also be detected) - of course, it is the same as the first two The same method, still can only know whether it is grounded, the specific grounding quality, there is no way of knowing.
1 A good ground wire has a resistance value of about 4 ohms,
2. First try to press the leak protection test jump button to see if the leak protection device is working.
3. When the power is on, I use the pointer multimeter to measure the voltage difference between the zero line and the ground line. Only when the meter is adjusted to the variable current 10V gear, I can measure the voltage of 3 to 5V. Therefore, to measure whether the ground wire is well connected to the ground, you can use a multimeter to detect these two wires. If there is no small voltage, it means that the ground wire is broken.
4. There are metal water pipes in the ground in the house. After turning off the power, use a multimeter to measure the resistance between the zero line and the ground wire. The resistance value can be used within 6 ohms. Measuring the resistance of the neutral wire and the ground wire in the absence of electricity can best reflect whether the ground wire is qualified, the greater the resistance, the less safe it is!
5. Turn the multimeter to the current 50mA position. When the power is turned on, use the two test leads of the multimeter to connect one end to the neutral wire and the other end to the ground wire. If it can trip instantly, it means that the grounding is good.
Because the minimum sensitivity of the leakage protection is 15mA, if it can trip in this small range, and it is connected to the ground from the neutral line, it means that the ground line of the home is qualified.
