Digital multimeter how to distinguish between fire wire and zero wire
Multimeter to measure the DC voltage, it can be easily divided out of the wire that is the positive electrode and that is the negative electrode, when measuring alternating current can only read out the voltage is how much, and can not be divided into that is the zero line and the fire wire.
In fact, as long as we understand the characteristics of the multimeter, we can simply determine the zero fire line:
MF47-type pointer multimeter as a demonstration, first of all, the gear knob switch to select the AC500V gear, a finger lightly pressed in the black pen on the metal needle (finger pressure pen needle the tighter the higher the reading). The largest reading is the fire line, zero line did not read. Sometimes there will be a potential difference in the measurement, the largest reading is the fire line, followed by the zero line, the smallest for the ground line.
The second method is, the black pen line around the left hand in 2-3 circles, of course, the more circles the better the higher the reading. Fear of people can also put the black pen contact on the ground or wall (ground and wall special dry readings are not big and inconspicuous).
Say again the principle of the power test pen, electric pen by the front metal, carbon resistor, neon bubble, and tail metal cap composition, neon bubble for the light-emitting instructions for the device, carbon resistor resistance value in 1M ohms or more, the tail metal cap is the human hand in contact with the parts, when the human and the metal cap in contact with the fire wire, the pen, the human body and the earth constitutes a circuit, the neon bubble luminous. Which exists between the person and the earth about 100PF capacitance, the circuit is so constituted. The voltage of the pointer multimeter stall resistance of about 20K ohms / V (digital multimeter resistance 10M ohms) and the human body constitutes a circuit to read to determine the zero fire wire.
Electrical work in the multimeter is the most commonly used tools, multimeter can measure the voltage, can also measure the current, can also measure the resistance, can also measure the through and through, of course, to determine the zero line and the fire line is also very simple.
The following electrician home to you with the most commonly used digital multimeter to distinguish between the home electricity of the firewire and zero line:
With the multimeter to distinguish between fire and zero line, we have to insert the black pen in the public end, that is, the black hole on the multimeter, the red needle inserted in the red hole, written above the VAC that hole, that is, the AC voltage file;
Use the multimeter to determine the zero line and fire line, first we need to know the approximate voltage of the line to be tested, for example, residential electricity are about 220V, then we choose the range is 750V, is the middle of the rotary switch to 750V gear;
Then we use the left hand to the black needle and the wall or ground contact, with the right hand holding the red pen, with the pen to contact the line to be tested or jacks and other charged points, we observe the multimeter readings;
If the reading of the multimeter is about 220V, then I can confirm that this is the firewire; multimeter reading if it is very low, that is, about 20V, then we can confirm that this is the zero line;
In the same way we can also confirm which is the earth wire, if the reading of the multimeter is close to 0, then we can confirm that this is the earth wire;
In this way, we will use the multimeter to distinguish the line in the fire wire, zero wire and ground, feel is not very simple;
Finally, we suggest that it is not a professional electrician best not to operate on their own, although it seems simple, but there is still a danger.
