Electrician this technique is very simple, I want to take it out and talk about it is a bit of a fuss, I watched TV yesterday said that there are local futures, the police initially believe that it is caused by a short circuit in the wire or a wire ignition. Therefore, today I would like to rely on my understanding of this aspect, from how the line will be ignited, why it will be short-circuited, and its standard practice, if your peers think it is inappropriate, please correct.
First of all, let's take a look at a few diagrams here. The top of the picture below is a secondary ceiling, I will take it as an example to talk about the wire practice in the roof:
Remind everyone to make sure that every wire is protected by a string tube when working, and the tail end of the downlight is protected by a snakeskin tube because it needs to be bent and shifted.
The usual wire joints are connected in this way to ensure that the wire joints do not occur ignition, short circuit, and poor contact. This is the construction specification, which is what every electrician should do.
The branch line is this connection, the main line can not be truncated, and the attached wire is wound around the main line for 6-8 turns. The phenomenon of ignition, short circuit, poor contact of the wire is very serious, it is very simple to deal with, the wire ignition and short circuit is caused by the lack of the correct terminal, after the terminal is loosened, the electric ions will be generated when the high load current passes, and the electric ions repel each other like the welding spark of electric welding, and the temperature has also risen, and quickly, if it can be glued, it will be energized, and it will form a short circuit if it cannot be electrified.
Now if the terminal head is exquisite, the wire should be wrapped in fireproof tape, its role is to prevent electric fire from burning things, which is very important in the ceiling, especially now that many ceiling materials are made of wood keel, it is more necessary to do this!
The end of each wire must be treated in this way, so as to effectively avoid the danger of electric shock, and it is also to see whether the worker's workmanship is professional from the subtleties.
Faults such as ignition, short circuit, and poor contact of wires are not only in the connectors, but also in the junction box. There are many phenomena that there is no problem with water and electricity in the new house, and the problem will appear after the decoration is over. Looking at the chaos is actually regular, the red is the fire line, the basket is the zero line, the flower is the ground wire, the wire cap is disposable, some workers open the line and use the tape to simply deal with it, which is not correct.
The treatment of the connector in the upper wire box is as follows;
This is the connection method when there is an external power supply in the line, the usual wire joints are connected like this, in order to ensure that the wire joints do not occur ignition, short circuit, and poor contact phenomenon, the branch line is this connection, the main line can not be truncated, and the attached wire is wound around the main line 6-8 circles.
So everyone should pay attention to the importance of the ground wire, and don't forget the ground wire while pulling the socket.
When there is a wire, short circuit, and the chassis is electrified, the ground wire can transmit the power supply down, and the input is diffused to the earth, so as to protect the safety of people and machines, and its biggest role is the wire.
Electrician includes: strong current, weak electricity, after the end of the electrician, there must be, a strong current layout drawing, a weak current layout drawing, a list of engineering costs, a warranty certificate;
The following is a diagram of the strong current transformation:
Speaking of the second step of a home improvement electrician, let's talk about the third step of a home improvement electrician.
Step 3: The comprehensive arrangement of the existing switch and socket with strong and weak current, of course, is the process of going to the wall on the drawings you designed, whether there is a conflict between strong current and weak current;
1. Weak current and strong current can be in a wire duct, but not in a wire tube;
2. The distance between the sockets of strong and weak current is at least 30 cm;
3. The beauty of the line pipe is not horizontal and vertical, but the nearest distance and the least bending are scientific, economical and reasonable;
4. Now do a lot of floor heating, and those who wiring underground should be as close to the wall as possible. Because the heat of underfloor heating will accelerate the aging of electrical wiring.
Here is a reminder that you should first play the ink line traces of weak electricity and strong electricity, but when slotting, you should do the order of strong electricity and then weak electricity step by step, not to be confused.
If there is space in the line pipe in the wall, it is best to use it, and every meter of opening has the risk of breaking the line pipe. Therefore, when I am doing the project, I always want to find the drawings provided by the property company, so that the original line pipe will not be cut when the trunking is cut in the future.
Next, I will tell you the fourth and fifth steps of home electricity change.
Step 4: Tick the groove
This is the best job to do, as long as you are careful not to cut the conduit inside the wall.
Step 5: Buried pipe, wiring.
There are a few rules on this step:
1. The depth of the trunking is the diameter of the trunking + 1 cm of the plastering layer;
2. Make the wire pipe first and then string the wire;
3. There can be no joints in the line pipe (including strong and weak current);
4. The wires can not be confused (all the switches are controlled by the live wire 220V), the neutral wire (0V) ground wire.
It is best to use three colors for three wires, as confusing the wire items will cause a short circuit.
1
Here's the first connection
Note: There should be no connector in home decoration, especially in the line pipe, and if there is a connector, it should be in the wire box. The usual wire joints are connected in this way to ensure that the wire joints do not occur ignition, short circuit, and poor contact.
2
The following is the second connection method (fireproof tape isolation method), mostly used in the hanging item, or in the more high-energy project, the main line can not be broken, the rune line around the main line for 6-8 weeks, the spotlight in the ceiling, there should be many lights along the way This is the connection, wrapped in the fireproof tape, its role is to prevent electric fire from burning things, which is very important in the ceiling. The outside is then wrapped with insulating tape.
3
The following is the third way of connection: that is, the wiring method of crimping, this method is the most standardized and practical, but it needs special tools to do, the crimping pliers to crimp the line, the special pliers used for the crimping wire, set on the crimping line, press it hard. In addition, it should be said that the size of the crimping is related to the number of wires according to the size of the crimped wire warp, and we commonly use the T4 type, which is a millimeter in diameter and can press four wires of four square millimeters.
We have seen many wire accidents, some of which are caused by overloaded use of wires, and the other part is caused by loose joints of wires. The joints in the wire box do not meet the specifications, the wire is not under load, there is no matter, as long as the switch is pushed, it will trip, and the junction box of the wire will "snap" a few times of fire, and then there is a trip sound, this phenomenon is all due to the fact that the joint of the wire is not standardized, and the voltage is caused by poor contact under load.
About the live wire, the neutral wire, the ground wire
In order to make the alternating current have a very convenient power conversion function, usually the power transmission is in the form of three phases and four wires, the three ends of the three-phase electricity are called phase wires, and the three tails of the three-phase electricity are connected together to be called neutral wires and also called "zero wires". The reason why it is called the neutral line is that there is no current passing through the neutral line at the time of three-phase equilibrium, and then it is directly or indirectly connected to the earth, and the voltage with the earth is also close to zero.
The ground wire is a line that reliably connects the shell of equipment or electrical appliances to the earth, and is a good solution to prevent electric shock accidents.
In general, in a three-phase circuit, the live wire uses three colors of red, yellow, and blue to represent the three live wires, and the neutral wire uses black. In single-phase lighting circuits, yellow is generally the live wire, blue is the neutral wire, and yellow and green is the ground wire.
In some places, red is used for the fire wire, black for the neutral line, and yellow and green for the ground wire.
Is it possible to connect the ground wire and the neutral wire together?
It is not safe to connect like this, so it is not allowed.
The zero line is connected with the earth at the transformer end, because there is a certain resistance from the transformer to the user's zero line, so the voltage between the zero line and the ground at the user end is often not zero, if there is no ground wire, if the electrical appliance fails, the zero wire or the live wire is connected with the metal shell of the electrical appliance, then the voltage between the electrical appliance and the earth is not zero, so it is not safe, if the zero line is disconnected, then it is very dangerous. The ground wire is a line that the user is grounded nearby, and the voltage of the ground is zero under normal circumstances, and the good ground wire is connected to the metal shell of the electrical appliance, and when the electrical appliance fails, it can ensure that the voltage between the shell and the ground is zero, so that it plays a role in safety guarantee.
If the neutral wire and the ground wire are combined as one line, if the wire is disconnected and the switch of the appliance is closed, even the normal appliance will be charged to the entire shell, which is very dangerous.
Therefore, when using electricity, in addition to connecting the live wire and neutral wire, the electrical appliances with metal shells should also be grounded for the safety shell.
In practice, you are given three wires, one is the live wire, one is the neutral wire, and one is the ground wire, if the three wires are the same color, how can you tell them apart?
1. The color of L (Live) must be red, yellow, and green;
The color of the neutral line N (Neutral) must be black and blue;
The color of PE (Protect Earth) must be yellow and green.
2. Will you use a clamp ammeter to measure the live wire with an electric pen? The current of the phase wire (live wire) and the neutral wire is the same, and there is no current on the ground wire when it is normal.
3. The neutral wire is the current flowing through, the ground wire is for protection, there is no current in normal operation, only when there is a short circuit and leakage, the grounding resistance is very small, and the equipment end is generally protected by the shell and grounded.
Measure the live wire with an electric pen, and place the test light (with a wired bulb) on one of the live wires and one of the other two wires, if the light is on, it means that it is the zero line. If the light is not on. The description is a ground wire.
The test light method is effective when the ground wire is not connected to the ground, if the ground wire is connected to the earth, then the light will be on no matter which line is connected.
4. In the case of electricity, it should not be difficult to find the live wire, the difficulty is to distinguish the neutral wire and the ground wire, theoretically: the voltage between the live wire and the neutral wire is about 220 volts, and the voltage between the ground wire is about 190 volts. If you connect an energy-saving lamp, the brightness should be visible, and the bright nature is the zero line, which is for reference only.
The difference between the live line and the neutral line
The live wire and the neutral wire are both live wires, if the two-phase power supply is connected to the electrical appliance, then there is an electric current flowing through the wire, and the general feeling is that the live wire is electrified because if the person touches (including some indirect contact) the live wire, a part of the current passes through the human body.
It's like a water pipe, but there is a faucet in the middle. The neutral line is not charged because the other end of the power supply (neutral wire) is grounded, and when we touch the neutral wire on the ground, because there is no bit difference, no current will be formed. So there is a feeling that the zero line is not charged. Both the neutral wire and the live wire are originally from the power supply, and the positive direction of the current is from one out, and through the external equipment from the other end, forming a loop. The difference between the neutral wire and the live wire is that one of the two terminals of the power supply is connected to the ground.
The difference between the neutral wire and the ground wire
1. The zero line and the ground wire are different concepts, not the same thing;
2. The ground potential of the ground wire is zero. the nearest point of the electrical appliance used;
3. The ground potential of the neutral line is not necessarily zero. The nearest grounding point of the neutral line is at the substation or the transformer that supplies the power;
4. When your electric stove is not hot, don't think that there is no electricity, you can't power people, wrong! There may be such a possibility, far away from your electrical appliances N line is disconnected, with a voltmeter will find that the LN line of the electrical appliances are the voltage of the mains!
5. The ground wire will not electrify, unless it is a very bad situation, the designer does not understand, or messes around with the product;
6. If you have a neutral and ground wire in your circuit, you will find that there is a high withstand voltage capacitor in the middle of them.
Why can't ground zero be shorted?
When the ground zero is shorted, in case the live wire and the neutral wire are reversed, the entire cabinet will be connected to the live wire, and it will be electrified.
Why can't the live wire and the neutral wire be reversed?
In the internal design of electrical appliances, the circuits of the neutral and ground wires will be different, for example, a fuse will be added to the live wire.
SOME OF CISCO'S DEVICES ARE REVERSED AND CANNOT BE STARTED.
The line of fire is a common name for the phase wire.
Mains: refers to single-phase alternating current for household use, with an effective voltage of 220V.
Three-phase power electricity: refers to industrial electricity, and the voltage between phases is 380V. However, the voltage between phase and ground is 220V, which is the mains power supply mode.
Ground wire: In order to protect personal safety, all household appliances with metal shells must be grounded, and the obvious sign of the ground wire is yellow-green (half of the wire is yellow and half is green). It is absolutely forbidden to use the ground wire and the neutral wire together, because if the fuse of the neutral wire is broken, it will cause the household appliance shell to carry a 220V mains voltage, causing personal injury accidents.
The ground wire is also not allowed to be vacant, and the ground wire must be well grounded, usually with a ground resistance of less than 4 ohms. We test with a multimeter:
1. In the case of power failure, the resistance of the ground wire and the neutral wire should be infinite. If the resistance is 0, the ground wire and the neutral wire are connected in parallel.
2. When the electrical appliance is not connected to the mains, the ground plug of the power cord and the casing should have zero resistance, otherwise the contact will be poor.
Neutral line: Usually grounded at the power supply transformer, and at the same time grounded at the inlet line of the residential unit. When the neutral line is intact, there is no voltage between the neutral line and the earth.
Live wire: that is, any phase in the three-phase power electricity, its voltage relative to the neutral and ground wire is 220V, and the voltage between any two phases is 380V. Normally, the currents flowing through both the live and neutral wires are equal. The wire diameter of the live wire and the neutral wire is the same.
Color requirements: the live wire is red, green, yellow, the neutral wire is light blue, and the grounding wire is yellow and green wire.
FireWire (English LIVE) L is generally red or yellow or green
The neutral line is generally blue
EARTH E is generally yellow-green (flower line) or black
The light switch should be connected to the live wire to avoid electric shock when changing the bulb.
The wiring of the socket: the left neutral wire, the right live wire, the middle ground wire, to adapt to the higher requirements of electrical appliances
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