How to determine the neutral line and the grounding wire, and how is the neutral wire grounded?

1.First, use an electric pen to find the live wire (the line that the electric pen lights on), connect the end of the bulb to the live wire, and name the remaining two wires: Line 1 and Line 2.

2.First use line 1 to contact the other end of the lamp, if the brightness of the bulb is normal, it is regarded as line 1 is the zero line, and when the other end of the lamp is touched with line 2, the leakage switch will blurt off the switch at this time, line 2 is the ground wire.

3.In addition, if the color code of the line is standard, three lines can be divided according to the color code. Red is the live wire, blue is the neutral wire, and yellow-green is the ground wire.

1. If the external grounding wire is connected normally, the zero line cannot be measured with a multimeter, the live wire to the neutral wire is 220V, and the neutral wire and the grounding wire are zero. Because both the neutral and ground wires are grounded. If the grounding wire of the live wire is lower than 220V or there is no voltage, and the neutral wire and the grounding wire are not zero, it means that the grounding wire has been disconnected or the grounding is seriously bad, and the grounding wire is meaningless.

2. You can distinguish by wire diameter or color, generally the fire wire is the same thickness as the neutral wire, the grounding wire is a uniform square millimeter, and the grounding wire is a two-color wire. You can also use the principle of "left zero and right fire on ground" of the socket to determine the grounding wire.

3. If your line is not installed standard, and the method of 2 can not be determined, it is necessary to disconnect the grounding wire before entering the wall to measure, at this time, the 220V is measured is the live wire and the neutral line, and the zero V or several V is the live wire and the ground wire, the neutral wire or the grounding wire. If the live wire is measured to be grounded at this time, the live wire is 220V to the neutral wire, and the neutral wire and the grounding wire are zero, which means that the grounding wire and the neutral wire in your home have been mixed together. If it is measured that the live wire is 220V to the neutral wire, the live wire has tens of volts or lower than 220V to the ground wire, and there is a voltage of tens of volts or lower than 220V between the neutral wire and the grounding wire, it means that there is serious leakage of electrical appliances in the home.

Be sure to resume after disconnecting the measurement.

It should be noted that the neutral wire and the grounding wire cannot be mixed and substituted, and the mixed and substituted are not protected, and the risk of electric shock is greater.

The neutral line is connected to the neutral point of the transformer, if the neutral point of the transformer is not grounded, when the three-phase load is balanced, the neutral point of the transformer is 0 potential, which is of course no problem, but in fact, it is impossible to make the three-phase load completely balanced, the three-phase load is unbalanced, the neutral point of the transformer will drift, that is, the potential of the neutral point of the transformer is no longer 0, so that the potential on the neutral line is not 0, scattered This is what we often call the zero line live, very dangerous.

Therefore, the neutral point of the transformer must be grounded, that is, zero must be grounded. Normally, the neutral wire is repeatedly grounded with the ground wire at the neutral point of the transformer, and the voltage is the potential difference between the two points.

1. Earthing refers to the neutral point of the power system and electrical installation, the exposed conductive part of the electrical equipment and the external conductive part of the device connected to the earth through the conductor. It can be divided into working grounding, lightning protection grounding and protective grounding. The working grounding is set by the operation needs of the power system (such as the neutral ground), so under normal circumstances, there will be a long-term flow of current through the grounding electrode, but only an unbalanced current of a few amperes to tens of amperes.

In the event of a grounding fault in the system, there will be thousands of amperes of working current flowing through the grounding electrode, but the current will be cut off by the relay protection device, even if it is a backup protection, the action is generally within 1s. Lightning protection grounding is a grounding designed to eliminate the dangerous effects of overvoltage, such as the grounding of lightning rods, lightning wires and lightning arresters. The lightning protection grounding will only flow under the action of lightning impact, and the lightning current amplitude flowing through the lightning protection grounding electrode can reach tens to hundreds of thousands of amperes, but the duration is very short.

Protective grounding is a grounding set up to prevent equipment from endangering personal safety due to insulation damage and electrification, such as metal shells, reinforced concrete poles and metal towers of power equipment. Protective grounding will only flow through the equipment if the insulation is damaged, and its value can vary over a wide range. When the current flows through the above three types of grounding electrodes, the potential of the grounding electrodes will increase, which will affect the safety of people and equipment.

For this purpose, it is necessary to limit the potential increase of the grounding electrode or to take appropriate safety measures to ensure the safety of equipment and personnel.

2. The ground wire is a wire connected to the earth, the shell or the wire with zero reference potential in the electrical system or electronic equipment. On general electrical appliances, the ground wire is connected to the shell to prevent electric shock accidents caused by the internal insulation damage to the shell. Ground wire is short for grounding device.

Ground wire is further divided into working grounding and safety grounding. In order to prevent people from electrocution accidents when using electronic equipment such as home appliances and offices, the protective grounding is a kind of safety grounding guard. A ground wire is a wire in an electrical system or electronic device that is connected to the ground, to the enclosure, or to a wire with a reference potential of zero.

On general electrical appliances, the ground wire is connected to the shell to prevent electric shock accidents caused by the internal insulation damage to the shell. The symbol for the ground wire is pe; It can be divided into two types: power supply ground wire and circuit ground wire. According to the current standard in China, when the third circuit in GB2681 is marked according to the color of the wire, it should generally be the phase wire - phase A yellow, phase B green, and phase C red.

Neutral wire - light blue, the ground wire is yellow and green, if it is a three-pin socket, the left is the neutral wire, the middle (top) is the ground wire, and the right is the live wire.