How to measure Zero Fire and Ground with a multimeter
AC is the only way to talk about zero and fire wires. Then adjust your multimeter to the AC voltage setting, which is the setting with the wave that is marked under V. Measure the voltage between the two wires first. If the measurement is around 380 then both are firewires. If the measurement is around 220, it means that one of the two wires is fire. Then one of the multimeter pens will measure the grounding body, and the other one will measure one of the two wires, and the voltage at about 220 is the fire wire, and the other one is the zero wire.
How to measure the leakage? Leakage should be tripped ah, no power how to measure? Only to measure the resistance. If the ground is not tripped, then one of the three fire wire and zero wire potential equal. A pen to measure the zero line, another pen to measure the three wires, one and the voltage between the zero line is close to zero, it means that this one is grounded.
1, AC power between two fires for 380V, multimeter dialled to AC 500V ~ file, the red and black pens measured reading 380V ~
2, AC power has a fire a zero for 220V, the multimeter dialled to AC 250V ~ file, the red and black pens measured readings of 220V ~
3,How can the multimeter distinguish the fire line and zero line? In the case of line power, wall socket: on the ground, right fire, left zero.
4, in only three lines do not know that line is fire, zero, ground, and is charged, the first 500V ~ gear were measured two lines, mainly to prevent the 220V range will break the multimeter, if the three lines inside only 220V, that proves a fire, a zero, a ground,
5, the fire wire and the qualified ground line is also 220V, but the zero line and the ground line is only about 5V ~ if you use a mobile phone charger through the multimeter current gear and the three wires between the respective test power, when the fire wire and the ground line connected to the charger will be tripped.
6, after disconnecting the main gate, the multimeter to 10K file, between the three wires does not exist between the readings show that if there are readings will cause leakage, (this is no way to have to use the multimeter when the practice)
7, such as resistance 10K file test rice cooker in three lines, which line and shell readings, are proof of leakage.
Equipment leakage, the metal casing to the ground will have voltage, the multimeter hit to the AC voltage block, the meter pen a contact metal casing a contact ground or equipotential terminal, the table shows the voltage that the metal casing is charged, that is, leakage. Distinguish between the fire wire or zero line, the available meter pen a contact wire a contact wall, the needle swing is the fire wire, does not swing is the zero line.
Leakage is also the insulation resistance drop, by the environment and time, the degree of leakage will be different, using a multimeter to measure the insulation resistance of electrical appliances, or the insulation resistance of the power cord, in general, is not accurate enough. Measurement of insulation resistance first cut off the power supply, can not be operated with electricity. Multimeter power supply is a 9-volt base battery and 1.5-volt dry cell, voltage and current is low, slight leakage position, in the air and the environment is dry, the insulation resistance is very large when not easy to find, so that is not accurate enough, the majority of cases can still be used with a multimeter. More certain measurement tool is megohmmeter, it is a small hand-cranked DC generator, voltage nominal value of the general points, 500V, 1000V, 2000V, the output current by the rectifier circuit of DC, divided into positive and negative ± pole and ground. It is injected into the measured load voltage and current is higher, the reliability is also higher. Distinguish fire wire zero line first look at the wire skin colour, in the power distribution box cabinet three-phase colour varies, civilian electricity look at their own home switch box, the stylus measured what colour line has electricity, remember to know which line in the room is the firewire. Unexpectedly, some electricians are limited by the material, or do not know too much, or too much trouble, firewire zero line or even ground is a colour, as it was in the construction stage, the new installation line as long as you remember the location, or temporary good mark, connected to use. Out of order, and then the repairer does not know, can only use the multimeter line pull apart, a person standing at the power box, a person in the checkpoint to measure the resistance value, the distance is much longer than the line used by the multimeter is much longer, and can accurately distinguish which line is which, and then connected or re-programmed to connect. There is another situation is that the line is complete with electricity, but there is no measuring tool, and want to know which line is the firewire, that is, standing in the front of the three-hole socket power supply, the left is the zero line, the right is the firewire, the top is the ground line, the lighting switches should be all controlled by the firewire, there is no zero line inside, which are all the national standards.
