How to measure leakage voltage with a multimeter. How to distinguish between fire and neutral wires.
With a multimeter or electronic multimeter, how to measure the leakage voltage. Now most of the enterprises, individual households with electricity is 220 volts alternating current centre line is into the ground, at the same time, the protective ground line is also accessed to the earth respectively, so the centre line (work line) and the protective ground gas is set up separately, so there is a potential difference between the two kinds of ground, so this potential difference can only be close to the 36-volt, the voltage is too low can't be distinguished from the work line and the protective ground gas is regarded as the same line. Protective ground can not play the role of leakage protection, is very dangerous.
If the use of equipment shell once the leakage, it will produce leakage voltage, more than 36 volts AC voltage will be dangerous.
Therefore, you should usually pay attention to the equipment insulation and leakage situation.
To know and measure the leakage voltage situation, the method is very simple and practical, the way is very earthy. As long as there is a multimeter (AC gear head from high to low), two table stick one hand on the wet lot or water pipe, the other hand on the chassis, such as more than 36 volts is a dangerous voltage.
Another note, for high-voltage DC power supply is not directly into the ground at the other end, will not produce leakage voltage to ground. But beware of hands touching the second line voltage, is also very dangerous.
Distinguish between the fire line or work line (centre line), is the same principle, the meter stick one hand on the wet ground or tap water pipe. Another meter stick any ride on the fire wire, voltage can be immediately distinguishable.
With the simplest way, a measurement of zero line fire line ground, close the switch, the digital multimeter hit the AC file, the mechanical multimeter hit ~, the voltage stops should be higher than the measured voltage, such as the measurement of 220 volts hit 500 volts or 750 volts, one end of the ground such as a sewer pipe or indoor total zero, both places are not okay to tie up the wall is also okay, but outside the side of the ceramic tile wall. At this time the voltage is not high or low, because the wall is not wet or dry, so the voltage will not be the same. As long as read out a few dozen volts or some more, this line is the fire wire. Disconnect the gate, with a multimeter resistance maximum block, pointer 10K or l00K, digital is also the highest block, the smallest reading, is the ground line, resistance value is slightly larger for the zero line. Friends of the renovation of the home, the completion of the power trip, the renovators to find their electrician to get two days did not find the fault, the electrician had to find the village electrician, the village electrician to get a few days also did not find out what is wrong, and later found out that several places of the socket, zero fire wire mixed, mixed up with the place of the socket is low, it is not good, which led to leakage of electrical appliances tripped.
As for the leakage if the household appliances, with a multimeter 10K gear electrical parts, if the resistance measurement is very small, a few ohms or dozens of ohms, that electrical insulation damage or aging, moisture, etc., there will be leakage phenomenon, household appliances such as television, computers, stereos, etc. Do not use a shaking table to detect, otherwise the test is over, your equipment will be finished playing, because the shaking table voltage of thousands of volts, it will damage the components of the electronic equipment. If the home indoor leakage place, you can first use the multimeter resistance block to measure, the experience is away from the point of failure is almost impossible to measure, that is, the resistance value is very large, and sometimes do not move, the closer to the point of failure, the smaller the value of the resistance, so that the operation is better than shaking the table much better. If the leakage condition is very small, it has to be measured with a shaking table, rural outdoors inserted into the ground an iron rod, connected to a line, upstairs in the total location or ground, the other side to take the disconnection method of detection, because the upstairs sockets are connected in parallel, to take the sectional detection of the exclusion of the method, that is, from the middle of the house after the disconnection, divided into two measurements, which is the detection of the simplest method.
