Method of measuring whether a line is shorted or grounded using a multimeter
Multimeter to measure the current in the ground line, if there is current in the ground line, then the phase line is grounded. If there is no obvious current value in the ground line, in the case of confirming the work of no electrical equipment to detect the zero line there is no current, if there is a current, then it is a phase-to-phase short-circuit or phase-to-zero line short-circuit.
This measurement is the most direct, if the power has been cut off, can not detect the current, you can consider using the multimeter resistance file to check the resistance between the zero line and the fire line, the resistance between the zero line and the ground line, the resistance between the fire line and the zero line, of course, if it is a 380V power supply you need to check the phase resistance between the fire line.
Of course, different ways of power supply, check out the conclusion is not the same, in the TT power supply system in the zero line before entering the house need to be individually grounded, the same need for the metal casing of the electrical equipment is individually grounded, this time to measure the resistance between the zero line and the ground resistance is normally lower, that is to say, the zero line and the ground line with the fire line short-circuited you check the results of the zero line and the fire line, the ground and the fire line between the resistance are relatively low, you can put the zero line and ground line resistance is relatively low, you can put the zero line and the fire line between the phase resistance. resistance are relatively low, you can remove the zero line into the house when the ground before checking.
In the TN-S power supply system is a three-phase five-wire system, there are three firewire, ground, zero line, this time to check the zero line and the ground line between the existence of a certain resistance resistance, the same method of checking when you need to go to cut off the ground line or the zero line, and then respectively, use a multimeter to check the zero line and the firewire, ground and firewire, firewire between the phases of the resistance to determine which place is short-circuited.
If the TN-C system is relatively simple, zero and ground is a line PEN, only need to go to check the fire line between phases, PEN line and fire line resistance between the resistance value can be.
In addition, it should be noted that: the most effective tool to check the short circuit is not a multimeter, should be used to check the corresponding voltage level of the swing meter.
