How to use a multimeter to test the quality of the ground wire of the socket at home
We don't have a professional grounding resistance tester at home - and it's not worth buying one specifically for this matter, so we can't know the specific grounding quality of the ground wire. But it is still possible to determine whether the ground wire is grounded or disconnected in the middle through simple measurements.
Set the multimeter to the AC voltage range of 250V~or the closest and greater than 220V, and measure the voltage between the live and neutral wires, as well as between the live and ground wires.
If the difference between 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 testing
Take a light bulb, connect one end to the live wire and the other end to the neutral and ground wires respectively, and compare the brightness of the two light bulbs.
If the brightness is the same twice, or if the bulb slightly dims when connected to the ground wire, then the ground wire is well grounded; If the bulb does not light up when connected to the ground wire, then the ground wire is faulty.
Note: When testing with this method, there should be no leakage switch in the circuit, otherwise the leakage switch will trip when testing the ground wire, making it impossible to compare.
Phase detector
This thing is cheaper than a multimeter, around 10 yuan, and many brands have it. Ordinary users should keep it on hand at home.
It's also quite convenient to use. Simply plug it into the socket and observe the sequence of the three lights on the detector. By comparing with the example, you can know if the ground wire is normal (faults in the neutral and live wires can also be detected) - of course, just like the previous two methods, you can only know if it is grounded, and the specific grounding quality is unknown.
A good grounding wire has a resistance value of about 4 ohms
First, try pressing the leak protection test button to see if the leak protector is functioning properly.
When powered on, I used a pointer multimeter to measure the voltage difference between the zero crossing line and the ground line. Only when the meter was set to the 10V converter level, did I measure a voltage of 3 to 5V. So, to measure whether the ground wire is well grounded, a multimeter can be used to check these two wires. If there is no low voltage, it indicates that the ground wire is broken.
There are metal water pipes that enter the ground in 4 households. After turning off the power, use a multimeter to measure the resistance between the neutral wire and the ground wire in the ohm range. As the resistance of each water pipe varies depending on its age, it can still be used if the resistance between it and the ground wire is within 6 ohms. Measuring the resistance of the neutral and ground wires in the absence of power can best reflect whether the ground wire is qualified. The larger the resistance, the less safe it is!
