How to use a multimeter to test the goodness of your home outlet ground wire
We don't have a professional ground resistance tester in our house - and it's not worth getting one just for that - so there's no way to know the exact quality of the grounding of the ground wire. But it's still possible to tell if the ground is grounded, or if it's disconnected in the middle, by simple measurements.
Multimeter test
Multimeter set to 250V ~ or the closest and greater than 220V AC voltage gear, respectively, to measure the voltage between the fire wire and the zero line, fire wire and ground.
If the difference between the two voltages is less than 5V, it proves that the ground is well grounded - and the smaller the difference, the better the grounding quality.
Light bulb test
Take a light bulb, one end is connected to the fire wire, the other end is connected to the zero wire and ground wire, and compare the brightness of the two bulbs.
If the brightness of the two times the same, or connected to the ground when the bulb is slightly dark, then the ground is well grounded; if connected to the ground when the bulb is not bright, then the ground fault.
Note: This method of testing, the line can not have a leakage switch, otherwise the test ground leakage switch will trip, can not be compared.
Phase Detector
This thing is cheaper than a multimeter, about 10 dollars, many brands have, the average user family should always have.
1 A good ground wire has a resistance value of about 4 ohms,
2 first try to press the leakage insurance test jump button to see if the leakage insurance device is working.
3 in the case of power, I used a pointer multimeter to measure the voltage difference between the zero line and the ground line, only to adjust the meter to the variable current 10V gear, measured to have 3 to 5V voltage. Therefore, to measure whether the ground wire into the ground is good, available multimeter test these two lines, if there is no small voltage, indicating that the ground is disconnected.
4 home has a metal water pipe into the ground, after turning off the power, with a multimeter ohm file to measure the resistance between the zero line and the ground line, because of the new and old water pipes in each home, the resistance value is also different, but the amount of resistance between it and the ground line within 6 ohms can be used. In the absence of electricity to measure the resistance of the zero line and the ground line can best reflect whether the ground line is qualified, the larger the resistance the more unsafe!
5 the multimeter to the current 50mA gear, in the closing of the power, the two pens of the multimeter with one end of the zero line, one end of the touch ground, can be instantly tripped that is a good grounding.
