A simple way to measure wiring for leakage with a multimeter
Measure the 220V line is not a leakage with a multimeter, the simplest way is to cut off the power supply, the multimeter 抜 to the resistance block (500 ohms) will be the zero line and the fire wire were connected to the ground line with a multimeter with two pens, such as the results of the measurement of 0, so that it can be determined that the line is grounded, it will be a leakage.
Measurement of 220V line leakage should be 500V or 1000V shaking table shaking test is accurate, if the multimeter to measure the 220V line is not a leakage is not appropriate, and then if there is no shaking table on hand, then you can suspect that the leakage of power lines at the beginning of the temporary installation of a normal use of a double-pole leakage circuit breakers to test, connected to the leakage circuit breakers and closed leakage circuit breaker that is the time when the time, and its reset button is protruding. Is to protrude then (Note: If the reset button does not protrude the gate is overload protection and short-circuit protection gate) to prove that the line has a leakage phenomenon. This approach is relatively simple and accurate.
Multimeter to measure 220V leakage is not appropriate, because you want to measure the leakage current, the multimeter to measure the weak AC current is a weak point, measurement is not allowed to be more troublesome, if you have to measure the need for a current transformer, you might as well use a clamp meter to measure, but to choose the range of the appropriate sensitivity of some good clamp meter.
Suspected circuit leakage, you can use the open air with leakage protection to judge, segment by segment to determine the scope of the leakage, troubleshooting.
As for the resistance to measure the line leakage, I think it is not appropriate. Because since it is a leakage, that is, the resistance between the firewire and the protective ground is not infinite, but the multimeter voltage is not enough to explain the insulation between them, that is, 9V and 220V insulation resistance is very different. So the measurement of insulation resistance are measured at a higher voltage than that of the electricity used to obtain reliable data. That's why you have to use a rocking meter.
Of course, if you just measure whether there is a short circuit or path between the firewire and the protective ground, using a multimeter resistance block is also possible. You just can't measure the insulation data between them.
If the insulation skin of the line is damaged, you can visually see it and deal with it when the time comes. There is also a situation that the roll skin is not damaged, just some cracking, resulting in some grounding in the wet, or the damage is very hidden, people can not use the naked eye directly see. At this time, you can de-energize the line and shake it directly with a shaking meter. For low-voltage circuits, you should use a 500-volt shaking table. Ground measurement, if the insulation is less than 0.5 megohm. It can be assumed that the insulation is not very good and should be checked section by section. One point to note is that, when measuring with the shaking table, the circuit can not be connected to any electrical appliances. Otherwise, the measured value may not be allowed.
1, power outage measurement: shut down and disconnect all electrical appliances, with a multimeter RX10K file, a pen reception measurement of the firewire, the other pen ground (or faucet), should show the resistance to infinity, otherwise leakage.
2, charged measurement: with a multimeter 250 volts AC voltage file, measuring suspected leakage of the metal shell of the appliance, a pen connected to the shell, another pen grounded (or tap), the pointer shows that the voltage is higher than the 30-50 volts between, change the AC 50-volt gear, if the power supply to confirm that higher than 30 volts is a leakage, lower than 30 volts is normal, and then zero, the fire power supply plug line to the opposite side of the measurement can be determined once again. If the power supply is confirmed to be higher than 30 volts, it is leakage, and lower than 30 volts, it is normal.
3, fire and zero line (or fire and fire) between the leakage measurement: turn off and disconnect all electrical appliances, measuring the resistance between the fire and zero line should be infinite, otherwise it is a leakage.
