What needs to be done in each stage of integrated wiring design, construction and acceptance
How should the complex local area network integrated wiring system be implemented? What needs to be done in each stage of integrated wiring design, construction, and acceptance? Do you know the integrated wiring grounding system?
Generally speaking, due to the complexity of network integrated wiring, the detailed wiring system design should be carried out first, and then the construction should be carried out according to the design drawings and requirements. Only in this way can we achieve a targeted, strict construction in accordance with the design requirements to meet the needs of users.
Integrated wiring
First, the three main stages of integrated wiring
It is a complex system engineering to carry out general wiring in a large-scale building group, and it needs to be implemented step by step. The following is a brief description of several main stages of integrated wiring engineering.
1. System design stage
The design of the wiring system will have a decisive impact on the entire wiring process, so the designer should be careful and prudent, do a full investigation and research, and it is best to collect data related to the corresponding building, such as architectural drawings, decoration drawings and other projects. data of. If the building already has wiring, the data on the original wiring should also be collected. Then fully consider the economic factors, application requirements, construction schedule requirements and other factors.
If the building is still under construction and the requirements for integrated wiring are put forward, specific requirements can be put forward for the design of the building according to the overall layout and wiring requirements, such as the specification of the channel for wiring between the upper and lower floors, and some pre-buried pipes, etc. , which can provide convenience for future integrated wiring. Some wiring work that can be carried out synchronously is best reflected in the building design drawing, so that some wiring can be completed in the preliminary project at the same time of construction, which can avoid many disadvantages of later construction, reduce repetitive labor, and improve work efficiency. Do it reasonably and easily.
On the basis of the original building, the situation of synchronizing the wiring with the interior decoration project is different, and the design must be redesigned according to the actual survey and mastering of the information and decoration design of the original building. It is necessary to maintain mutual communication between wiring design and decoration design, which provides convenience for the work of both parties.
In general design, the selection of materials, equipment grades and layout arrangements are directly related to the user's application needs and capital investment. If the user's funds are relatively tight, they can choose some moderate solutions. In the purchase of cables and equipment, more attention should be paid to the cost-effectiveness. The distribution of information access points can also be relatively centralized, which can reduce the amount of investment in cables and equipment. Ultimately achieve the purpose of saving money. If the user is more economical and has higher requirements for wiring, higher-performance cables and equipment can be selected, and the information access points should be distributed as evenly as possible, and appropriately advanced for future expansion by users.
2. Construction stage
In the specific integrated wiring construction stage, since many factors may be involved, including communication with users and construction and decoration construction units, as well as the command of the construction site, and also need to master comprehensive standards and techniques, the commander must have a higher level of Quality.
If the decoration and wiring construction are carried out at the same time, generally speaking, the wiring construction team is required to enter the site earlier, and do a lot of preparatory work that can be done first, such as digging trenches on the wall, drilling, laying pipes, etc. In order to strive for the initiative, the wiring construction unit should strive to start the construction as soon as possible and carry out the construction in a planned way. For example, you can choose some typical places to do some tests to determine some details of the specific construction, which can provide experience and problems for the full implementation of the following projects. Solution. If problems are encountered, they can be solved as soon as possible. For problems that cannot be solved temporarily, the designer can propose corresponding supplements and modifications according to the construction situation on site.
For example, in the construction of the general wiring project of a building, due to the late preparation work, and the lack of ideological preparation of the decision-makers on what type of materials to use, and the inexperience of the on-site commanders, the result is very slow. At the same time, due to lack of experience and technology, some technical problems cannot be handled well, which makes the whole wiring project difficult.
Another example is that the partition walls of buildings are generally hollow bricks. If the method is not appropriate, or the force is too large, the whole brick may be broken, which will not only make it difficult for oneself to construct, but also cause dissatisfaction of the decoration department, making both of them dissatisfied. The relationship between them is very inconsistent. Due to the poor cooperation between them, the wiring process cannot keep up with the progress of the decoration, and the contradiction between the two parties is likely to be further intensified, affecting the overall progress. Therefore, in this case, it is first necessary to have a good relationship with the decoration construction team (even including the specific construction personnel below), so that the project can be carried out in a coordinated atmosphere. Only in this way can the following work be coordinated with each other and carried out simultaneously .
In addition, the difficulty in pulling the wire must be taken into account during construction, and pipes with reasonable diameters should be used, especially in the case of many turns, it is necessary to leave as much space as possible, and fully consider the work of the next step. When pulling the wire, the two ends should be marked, and it should be divided into bundles according to a certain method to reduce the finishing work in the next step.
After the cables are all in place, the next step, such as making modules, upper panels, etc., generally has to wait until the other work of the decoration construction team (such as painting) is completed. If the module is installed before painting, some liquids such as lime water may soak into the module during painting, causing quality problems and rework. In the same way, if the panel is too early, the panel will be soiled, which will increase the workload of cleaning in the next step.
3. Inspection and acceptance stage
After the wiring work is completed, each information point should be tested and checked. Generally, special instruments such as FLUKE can be used for testing, and testing is carried out one by one according to the marking diagram of each information point. Do a good job of labeling during the test, mark each point number with label paper at the information point and the patch panel, and mark it on the floor plan, so as to manage, use and maintain the system in the future.
Generally, problems are found at both ends. This may be because the patch panel is not done properly, or the module may not be done properly. Another possibility is that the screws are drilled into the network cable when the upper panel is drilled to cause a short circuit.
After all the tests are completed, the floor plan is cleaned up, and finally a completely correct labeling diagram is made for future reference. At this time, it can be handed over to the user for acceptance. When the user is accepting, due to the professional level and equipment, the construction party will generally require the construction party to provide testing technicians and equipment. At this time, the construction party must provide as many as possible. Of course, because the wiring construction also has a warranty period (more than 10 years), the user's test acceptance is only a random test, and only the construction party is required to promise to solve the problems found in the actual network installation in time. And the test can not find all potential problems, the best test is to carry out the actual network environment when the specific application is fully deployed. In addition, the entire construction drawings and labeling drawings should be given to the user.
2. Precautions for integrated wiring
Integrated wiring is a systematic project, in which the knowledge is very large. The following are some experiences summarized in this article from the actual wiring project.
1. The best brand of wiring products is specific
The network products used in wiring, such as ordinary Category 5 twisted pair cables or crystal heads, etc., transmit weak signals, and a little carelessness may affect the overall performance of network communication. Although the wiring products produced by different manufacturers have some differences in performance and quality, for example, the quality of the network cables produced by some manufacturers is better, the crystal heads produced by some manufacturers are better in use, and the network interface modules produced by some manufacturers Not bad, but I still recommend using the same brand of cabling products in the same cabling system, because it can ensure maximum compatibility.
Many wiring people often simply think that if the "best" network products are combined for wiring, the attenuation of the network signal will be minimized and the best communication effect will be achieved. In fact, this understanding is incorrect, because the impedance of the internal materials of different manufacturers' network products is different, and the slight difference in the impedance may have a great impact on the signal attenuation of the high-speed network, thereby affecting the entire network system. communication quality. Practice has proved that the mixed use of product wiring from different manufacturers has little impact on network switching with a speed of less than 10Mbps, but if it is a network system with a speed of 100Mbps or higher, it will have a significant impact. Therefore, it is best to use network products produced by the same manufacturer for wiring.
2. Reasonable design before wiring and strict testing after wiring
It's a work habit issue. The importance of good work habits is better reflected in network wiring. Reasonable planning before wiring can greatly improve the efficiency of the network, otherwise it will seriously affect the network efficiency.
In the design phase, the needs of information system users are not adequately considered, and sometimes the situation is bad. For example, cable trunks connecting telephones and computers to buildings can be guaranteed, while connections to other building systems or equipment such as fax machines, clocks, security and fire alarm systems, elevators, property department systems, etc. are often neglected. To avoid this from happening, a detailed checklist of information systems and equipment can be prepared and provided to each department head for their participation in replenishment before the system is designed. In this way, the above situation can be avoided.
But in fact, it is difficult to guarantee that this situation will not happen again, because with the growth of user business volume and the change of business nature, the use needs of employees will also change. The office location of employees will be adjusted within or between departments, and the departments will also change arrangements. The cabling facility should be designed to handle these conditions, and the best approach is to plan a common cabling facility for all equipment. Unused spaces should also be cabled for future use, and the cabling facilities in each workshop should be able to meet the needs of any user. For example, a workstation should be set up to meet the needs of a finance person using a phone and a PC connected to a local network, as well as a research and development person using a phone, modem, and Internet-connected PC with a shared printer.
After the construction is completed, in addition to using the common Ping command to test whether the network is smooth, it is best to use some instantaneous burst high-throughput network exchanges to test. Because the ping command only checks whether the network is connected, if the network traffic is low, it is not a big problem, but when the network traffic is high, it may be difficult to access the Internet.
3. Correctly understand the definition of the 100m channel limit in the regulations
Everyone knows that the length of a single-segment network cable for Category 5e and Category 6 cables cannot exceed 100m, which is stipulated in the ANSI/EIA/TIA-568 standard. But here we must correctly understand the meaning of the 100m. According to the standard, this 100m should be the limit of the entire transmission channel in the horizontal section, namely the management subsystem + horizontal subsystem + working area subsystem, except for the 10m required for the cross-connection of the management subsystem and the working area connection cable, pre-buried The actual maximum length of the horizontal subsystem is usually only 90m, which is the basic transmission link length.
It can also be simply understood as follows: the entire transmission channel from the RJ-45 port of the network adapter in the work area to the nearest active connection device (switch, etc.) is up to 100m (including jumpers).
4. Correctly select each part of the communication cable
In the actual integrated wiring project, users often pay attention to the computer network or the immediate application, but lack enough attention to some important but not obvious requirements or future applications. If the pre-built wiring cable structure in the building does not match the actual cable facilities to be used, it will cause great delay in construction period and increase in cost. Architects and electrical engineering companies are often unfamiliar with the specifications and requirements of various types of wires, as well as the requirements of the Electronic Industries Association and the Telecommunications Industry Association (EIA/TIA) for cable structures in buildings such as conduits, cable reels, and equipment rooms. The set design parameters, if the design does not meet the specifications, the result may be that the existing conduit cannot accommodate all the cables that need to be installed, and additional conduits must be added, or the conduit has too many bends and there is no connection box, resulting in Difficulty in cable routing, or the use of cable reels and connection boxes that make the length of horizontal cables exceed the requirements of Category 5 cables
3. Integrated wiring grounding
When it comes to the grounding of integrated wiring, many readers and friends feel confused, and they will have the following questions: Why is the twisted pair wiring that is usually carried out not grounded? From this point, it can be seen that many users, even professional network administrators Not sure about grounding in network cabling, let alone its importance. In fact, this is determined by the lack of work experience or the limitation of responsibilities, because they have not conducted integrated wiring at all, if there is, it is only a single network wiring.
1. Grounding type of integrated wiring
Since the integrated wiring is aimed at a whole building or even a building group, its grounding is no longer a single grounding problem, but includes multiple levels of grounding systems. According to the provisions of the grounding and wiring requirements of commercial buildings, the grounding types of the integrated wiring system include six parts: grounding wire, grounding bus, grounding trunk, main grounding bus (general grounding terminal), grounding lead-in and grounding body. These six parts The corresponding installation position can be said to be from high to low (relative to the building), if the level is divided, it is from low to high. However, it should be noted that not all integrated wiring systems must have these 6 types of grounding. The following is a brief introduction according to the layers of the above-mentioned grounding lines.
(1) Ground wire
The ground wire is also commonly referred to as the ground wire, which is a type of grounding at the lowest level connected to the equipment, and is also the most terminal part of the entire grounding system. The grounding wire directly acts on each specific node. The two ends of the grounding wire are respectively connected to the node equipment and the grounding busbar to be introduced below, which is the next higher level of the entire grounding system.
Friends who have experience in copper coaxial cable wiring must still remember that in the copper coaxial cable ring wiring, there is an impedance matching terminal at both ends of each line, and the impedance matching terminal usually requires a metal object connected to the ground (usually a Connect with the computer metal case or metal window), this is the ground, and the line connecting the matching terminal with the computer case or metal window is the ground wire. Of course, although the function of the ground wire introduced here is the same, it is no longer connected to the computer case or metal window, but to a higher-level grounding system. All grounding wires are required to be copper insulated wires (the copper impedance is small, mainly for good grounding), the cross-section should not be less than 4mm2, and tin welding should be used as much as possible. Usually when wiring with shielded twisted pair cables, the grounding of the information socket can be connected to the wiring cabinet on each layer by using the shielding layer of the cable as a grounding wire. When the cables of the integrated wiring are laid through steel pipes or metal trunkings, there is no need for additional grounding. The steel pipes or metal trunkings can play the role of grounding, but they are required to maintain good electrical connections, and they should also have good electrical connections at both ends. ground.
(2) Ground bus
The ground bus is also called the floor ground terminal. As can be seen from its name, it is a common ground terminal specially used in the floor. One end of it should be directly connected to the grounding trunk line to be introduced later, and the other end of course should be connected to the grounding line connected to the distribution frame, distribution cabinet, steel pipe or metal trunking and other facilities on the floor. It belongs to an intermediate level, one level higher than the ground wire described above, and one level lower than the grounding trunk described below.
The ground bus is usually installed side by side with the horizontal wiring system in the floor and is used for the common grounding of the whole floor wiring system. The ground busbar should be copper busbar, and its minimum size should be 6mm (thickness) × 50mm (width), and the length should be determined according to the actual needs of the project. The ground bus should be electroplated with tin to reduce contact resistance (do not hand bond).
(3) Grounding trunk
The grounding trunk is used to centrally connect the grounding busbars on different floors, which is obviously one level higher than the grounding busbars described above. It is used for common grounding between different floors of the same building and is usually installed vertically between different floors. When designing the grounding trunk line, the structural form of the building, the size of the building, the routing and space configuration of the integrated wiring should be fully considered, and it should be coordinated with the laying of the integrated wiring cable trunk. The grounding trunk should be installed in a place protected from physical and mechanical damage, and the water pipes and metal cable shielding layers in the building cannot be used as the grounding trunk. The grounding trunk is preferably protected by a special shielding layer, such as into a steel pipe. When two or more vertical grounding trunks are used in a building, the top layers of the vertical grounding trunks shall be welded with insulated conductors of the same cross-section as the grounding trunks. The grounding trunk line should be an insulated copper core wire, and the minimum cross-section should not be less than 16mm2.
(4) Main grounding bus (general grounding terminal)
The main grounding bus, also known as the "general grounding terminal", is used for the common grounding of the entire building and is one level higher than the grounding trunk above. Generally, each building only needs one main grounding bus, one end of which is connected to the grounding trunk, and the other end is connected to a protector device. It is best to use a special shielding sheath. However, it should be noted that if there is only one grounding trunk in the whole building, this main grounding bus is unnecessary, and the grounding trunk also acts as the main grounding bus. The main grounding bus is used as the transfer point of the grounding trunk line and the equipment grounding line in the integrated wiring grounding system. The main grounding bus should be arranged on a straight path, and the welding wire from the protector to the main grounding bus should not be too long. The grounding lead-in (to be introduced below), the grounding trunk, the grounding wire of the DC distribution panel, all the grounding wires between the outside wire lead-ins, and all the metal frames for the integrated wiring located in the same wiring room as the main grounding busbar should be connected to the main grounding wire. The busbars are well soldered. When the outer wire entry cable is equipped with a shield or a metal protective tube, this shield and metal tube should also be welded to the main grounding bus. The main grounding busbar should be a copper busbar with a minimum section size of 6mm (thickness) × 100mm (width), and the length can be determined according to the actual needs of the project. Like the grounding bus, the main grounding bus should also be electroplated with tin to reduce contact resistance.
(5) Ground lead-in
The ground lead-in refers to the connection between the protector device and the grounding body (to be introduced below), which is relatively easy to understand. In order to achieve a good grounding effect, the grounding lead wire should be made of galvanized flat steel of 40mm (width) × 4mm (thickness) or 50mm (width) × 5mm (thickness). The parts should have measures to prevent mechanical damage, and should not be buried in the same place as the heating pipes.
(6) Grounding body
The grounding body is actually used to play the role of "earth" in ordinary grounding, and is divided into two types: natural grounding body and artificial grounding body. Natural grounding bodies include surface steel bars, pressure steel pipes and gates of reinforced concrete hydraulic structures that are in contact with water all the year round, metal embedded parts of trash racks, and metal bodies left in the ground or in water. The artificial grounding body usually refers to the steel products and copper plate products that are artificially buried in the ground. In the burial of steel products, there are two types of vertically installed grounding bodies and horizontally installed grounding bodies.
The vertical grounding body in the grounding system should be made of hot-dip galvanized steel with a length of not less than 2.5m (the length of the vertical grounding body can also be determined according to the soil quality and geographical conditions of the buried ground net), copper-clad steel, or a new type of grounding electrode. . The distance between vertical grounding bodies should generally be greater than 5m, which can be determined according to the size of the grounding network and the construction situation. The connection of the four corners of the ground grid should be buried with a vertical grounding body. The horizontal grounding body in the grounding system is generally made of hot-dip galvanized flat steel, and the horizontal grounding body should be connected with the vertical grounding body by welding.
The grounding body is generally made of hot-dip galvanized steel or copper. When hot-dip galvanized steel is used, the specifications are as follows.
Steel pipe wall thickness: should not be less than 3.5mm.
Angle steel: should not be less than 50mm × 50mm × 5mm.
Flat steel: should not be less than 40mm × 4mm.
Diameter of round steel: should not be less than 8mm.
When the integrated wiring adopts a separate grounding system, the artificial grounding body is generally used, and the following conditions shall be met.
The distance from the grounding body of the power frequency low-voltage AC power supply system should not be less than 10m.
The distance from the grounding body of the lightning protection system of the building should not be less than 2m.
Ground resistance should not be greater than 40.
When the integrated wiring adopts a joint grounding system, the steel mesh in the building foundation is generally used as the natural grounding body, and its grounding resistance should be less than 1. Joint grounding systems are usually used in practical applications.
2. Precautions
Safety grounding is a large-scale equipotential bonding with the earth potential as the reference potential. In the general concept, grounding refers to grounding, and not connecting to the ground is a violation of the basic requirements of electrical safety. This concept has limitations. For example, electric shock accidents and electrical fires rarely occur during aircraft flight, but the aircraft is not connected to the ground. The reason is that the safety of electricity use in the aircraft does not rely on the ground, but relies on equipotential bonding to ensure that the fuselage potential in the aircraft is reference potential for equipotential bonding. Due to the small range within the aircraft, even in the event of an accidental insulation damage, the potential difference is small, so the electrical safety on the aircraft is effectively guaranteed. People live on the earth, so they often need to be equipotential with the earth, that is, to connect the electrical system and electrical equipment housing with the earth, which is often referred to as "grounding". On the plane, the terminal can be used to connect with the fuselage, and on the earth, the grounding electrode is used as the terminal to connect with it.
The following issues should be paid attention to in the grounding design of the integrated wiring system.
(1) A complete shielding system requires shielding everywhere, and a continuous and complete shielding path can achieve the effect expected by the user. Therefore, if you choose to use a shielded system, in addition to cables, the modules, patch panels and other connectors need to be shielded, supplemented by metal bridges and pipes.
The principle of electrostatic shielding is that after the shield is grounded, the interference current flows into the ground through the outer layer of the shield, so it is very important to properly ground the shield layer. Otherwise, not only will the interference not be reduced, but more interference will be introduced. Metal tin foil is prone to tearing when terminated, so care should be taken not to damage the shield when stripping the wires. The stripping length of the ground wire in the shield should be minimized when terminating, because the shorter the stripping length, the less inductance it will cause and the better the grounding effect. When grounding on site, it is recommended to use a single-point grounding method to avoid voltage loops caused by multi-point grounding.
(2) The wiring equipment end of the shielding layer should be grounded, the user end should be grounded according to the specific situation, and the grounding at both ends should be connected to the same grounding body as much as possible. When there are two different grounding bodies in the grounding system, the root mean square value of the grounding potential difference should not be greater than 1V (effective value).
(3) When the cable enters the building from outside the building, it is easily affected by external factors such as lightning strike, power supply grounding, power supply induced potential or ground potential floating, which requires the use of protectors.
(4) The overvoltage protection device of the integrated wiring system should be a gas discharge tube protector. Because the ceramic shell of the gas discharge tube protector is sealed with two electrodes, there is a discharge gap between them, and is filled with an inert gas. When the potential difference between the two electrodes exceeds 250V AC voltage or 700V lightning surge voltage, the gas discharge tube begins to arc, providing a conductive path between the conductor and the ground electrode.
(5) The overcurrent protection of the integrated wiring system should choose a protector that can reset itself. Because of the various voltages that can appear on the cable, if the connected equipment provides it with a low-resistance path to ground, it will not be sufficient for an overvoltage protector to operate, and the current it generates could damage the equipment or cause a fire.
(6) When designing the grounding system, it should be fully considered that the line has overvoltage or overcurrent protection under any of the following dangerous environments: AC 50Hz voltage over 250V, working voltage over 250V power line contact Ground, large lightning strike, ground potential rises above 250V, etc.
The above introduces some of the main knowledge in the grounding of the integrated wiring system. It seems easy, but it is not easy to implement. In fact, the grounding of the integrated wiring is a system problem, which needs to be considered comprehensively, and should not be considered based on a certain machine, a piece of equipment, or even a floor. Only in this way can the grounding system of the entire wiring system be truly effective. How should the complex local area network integrated wiring system be implemented? What needs to be done in each stage of integrated wiring design, construction, and acceptance? Do you know the integrated wiring grounding system?
Generally speaking, due to the complexity of network integrated wiring, the detailed wiring system design should be carried out first, and then the construction should be carried out according to the design drawings and requirements. Only in this way can we achieve a targeted, strict construction in accordance with the design requirements to meet the needs of users.
Integrated wiring
First, the three main stages of integrated wiring
It is a complex system engineering to carry out general wiring in a large-scale building group, and it needs to be implemented step by step. The following is a brief description of several main stages of integrated wiring engineering.
1. System design stage
The design of the wiring system will have a decisive impact on the entire wiring process, so the designer should be careful and prudent, do a full investigation and research, and it is best to collect data related to the corresponding building, such as architectural drawings, decoration drawings and other projects. data of. If the building already has wiring, the data on the original wiring should also be collected. Then fully consider the economic factors, application requirements, construction schedule requirements and other factors.
If the building is still under construction and the requirements for integrated wiring are put forward, specific requirements can be put forward for the design of the building according to the overall layout and wiring requirements, such as the specification of the channel for wiring between the upper and lower floors, and some pre-buried pipes, etc. , which can provide convenience for future integrated wiring. Some wiring work that can be carried out synchronously is best reflected in the building design drawing, so that some wiring can be completed in the preliminary project at the same time of construction, which can avoid many disadvantages of later construction, reduce repetitive labor, and improve work efficiency. Do it reasonably and easily.
On the basis of the original building, the situation of synchronizing the wiring with the interior decoration project is different, and the design must be redesigned according to the actual survey and mastering of the information and decoration design of the original building. It is necessary to maintain mutual communication between wiring design and decoration design, which provides convenience for the work of both parties.
In general design, the selection of materials, equipment grades and layout arrangements are directly related to the user's application needs and capital investment. If the user's funds are relatively tight, they can choose some moderate solutions. In the purchase of cables and equipment, more attention should be paid to the cost-effectiveness. The distribution of information access points can also be relatively centralized, which can reduce the amount of investment in cables and equipment. Ultimately achieve the purpose of saving money. If the user is more economical and has higher requirements for wiring, higher-performance cables and equipment can be selected, and the information access points should be distributed as evenly as possible, and appropriately advanced for future expansion by users.
2. Construction stage
In the specific integrated wiring construction stage, since many factors may be involved, including communication with users and construction and decoration construction units, as well as the command of the construction site, and also need to master comprehensive standards and techniques, the commander must have a higher level of Quality.
If the decoration and wiring construction are carried out at the same time, generally speaking, the wiring construction team is required to enter the site earlier, and do a lot of preparatory work that can be done first, such as digging trenches on the wall, drilling, laying pipes, etc. In order to strive for the initiative, the wiring construction unit should strive to start the construction as soon as possible and carry out the construction in a planned way. For example, you can choose some typical places to do some tests to determine some details of the specific construction, which can provide experience and problems for the full implementation of the following projects. Solution. If problems are encountered, they can be solved as soon as possible. For problems that cannot be solved temporarily, the designer can propose corresponding supplements and modifications according to the construction situation on site.
For example, in the construction of the general wiring project of a building, due to the late preparation work, and the lack of ideological preparation of the decision-makers on what type of materials to use, and the inexperience of the on-site commanders, the result is very slow. At the same time, due to lack of experience and technology, some technical problems cannot be handled well, which makes the whole wiring project difficult. Another example is that the partition walls of buildings are generally hollow bricks. If the method is not appropriate, or the force is too large, the whole brick may be broken, which will not only make it difficult for oneself to construct, but also cause dissatisfaction of the decoration department, making both of them dissatisfied. The relationship between them is very inconsistent. Due to the poor cooperation between them, the wiring process cannot keep up with the progress of the decoration, and the contradiction between the two parties is likely to be further intensified, affecting the overall progress. Therefore, in this case, it is first necessary to have a good relationship with the decoration construction team (even including the specific construction personnel below), so that the project can be carried out in a coordinated atmosphere. Only in this way can the following work be coordinated with each other and carried out simultaneously .
In addition, the difficulty in pulling the wire must be taken into account during construction, and pipes with reasonable diameters should be used, especially in the case of many turns, it is necessary to leave as much space as possible, and fully consider the work of the next step. When pulling the wire, the two ends should be marked, and it should be divided into bundles according to a certain method to reduce the finishing work in the next step.
After the cables are all in place, the next step, such as making modules, upper panels, etc., generally has to wait until the other work of the decoration construction team (such as painting) is completed. If the module is installed before painting, some liquids such as lime water may soak into the module during painting, causing quality problems and rework. In the same way, if the panel is too early, the panel will be soiled, which will increase the workload of cleaning in the next step.
3. Inspection and acceptance stage
After the wiring work is completed, each information point should be tested and checked. Generally, special instruments such as FLUKE can be used for testing, and testing is carried out one by one according to the marking diagram of each information point. Do a good job of labeling during the test, mark each point number with label paper at the information point and the patch panel, and mark it on the floor plan, so as to manage, use and maintain the system in the future.
Generally, problems are found at both ends. This may be because the patch panel is not done properly, or the module may not be done properly. Another possibility is that the screws are drilled into the network cable when the upper panel is drilled to cause a short circuit.
After all the tests are completed, the floor plan is cleaned up, and finally a completely correct labeling diagram is made for future reference. At this time, it can be handed over to the user for acceptance. When the user is accepting, due to the professional level and equipment, the construction party will generally require the construction party to provide testing technicians and equipment. At this time, the construction party must provide as many as possible. Of course, because the wiring construction also has a warranty period (more than 10 years), the user's test acceptance is only a random test, and only the construction party is required to promise to solve the problems found in the actual network installation in time. And the test can not find all potential problems, the best test is to carry out the actual network environment when the specific application is fully deployed. In addition, the entire construction drawings and labeling drawings should be given to the user.
2. Precautions for integrated wiring
Integrated wiring is a systematic project, in which the knowledge is very large. The following are some experiences summarized in this article from the actual wiring project.
1. The best brand of wiring products is specific
The network products used in wiring, such as ordinary Category 5 twisted pair cables or crystal heads, etc., transmit weak signals, and a little carelessness may affect the overall performance of network communication. Although the wiring products produced by different manufacturers have some differences in performance and quality, for example, the quality of the network cables produced by some manufacturers is better, the crystal heads produced by some manufacturers are better in use, and the network interface modules produced by some manufacturers Not bad, but I still recommend using the same brand of cabling products in the same cabling system, because it can ensure maximum compatibility.
Many wiring people often simply think that if the "best" network products are combined for wiring, the attenuation of the network signal will be minimized and the best communication effect will be achieved. In fact, this understanding is incorrect, because the impedance of the internal materials of different manufacturers' network products is different, and the slight difference in the impedance may have a great impact on the signal attenuation of the high-speed network, thereby affecting the entire network system. communication quality. Practice has proved that the mixed use of product wiring from different manufacturers has little impact on network switching with a speed of less than 10Mbps, but if it is a network system with a speed of 100Mbps or higher, it will have a significant impact. Therefore, it is best to use network products produced by the same manufacturer for wiring.
2. Reasonable design before wiring and strict testing after wiring
It's a work habit issue. The importance of good work habits is better reflected in network wiring. Reasonable planning before wiring can greatly improve the efficiency of the network, otherwise it will seriously affect the network efficiency.
In the design phase, the needs of information system users are not adequately considered, and sometimes the situation is bad. For example, cable trunks connecting telephones and computers to buildings can be guaranteed, while connections to other building systems or equipment such as fax machines, clocks, security and fire alarm systems, elevators, property department systems, etc. are often neglected. To avoid this from happening, a detailed checklist of information systems and equipment can be prepared and provided to each department head for their participation in replenishment before the system is designed. In this way, the above situation can be avoided.
But in fact, it is difficult to guarantee that this situation will not happen again, because with the growth of user business volume and the change of business nature, the use needs of employees will also change. The office location of employees will be adjusted within or between departments, and the departments will also change arrangements. The cabling facility should be designed to handle these conditions, and the best approach is to plan a common cabling facility for all equipment. Unused spaces should also be cabled for future use, and the cabling facilities in each workshop should be able to meet the needs of any user. For example, a workstation should be set up to meet the needs of a finance person using a phone and a PC connected to a local network, as well as a research and development person using a phone, modem, and Internet-connected PC with a shared printer.
After the construction is completed, in addition to using the common Ping command to test whether the network is smooth, it is best to use some instantaneous burst high-throughput network exchanges to test. Because the ping command only checks whether the network is connected, if the network traffic is low, it is not a big problem, but when the network traffic is high, it may be difficult to access the Internet.
3. Correctly understand the definition of the 100m channel limit in the regulations
Everyone knows that the length of a single-segment network cable for Category 5e and Category 6 cables cannot exceed 100m, which is stipulated in the ANSI/EIA/TIA-568 standard. But here we must correctly understand the meaning of the 100m. According to the standard, this 100m should be the limit of the entire transmission channel in the horizontal section, namely the management subsystem + horizontal subsystem + working area subsystem, except for the 10m required for the cross-connection of the management subsystem and the working area connection cable, pre-buried The actual maximum length of the horizontal subsystem is usually only 90m, which is the basic transmission link length.
It can also be simply understood as follows: the entire transmission channel from the RJ-45 port of the network adapter in the work area to the nearest active connection device (switch, etc.) is up to 100m (including jumpers).
4. Correctly select each part of the communication cable
In the actual integrated wiring project, users often pay attention to the computer network or the immediate application, but lack enough attention to some important but not obvious requirements or future applications. If the pre-built wiring cable structure in the building does not match the actual cable facilities to be used, it will cause great delay in construction period and increase in cost. Architects and electrical engineering companies are often unfamiliar with the specifications and requirements of various types of wires, as well as the requirements of the Electronic Industries Association and the Telecommunications Industry Association (EIA/TIA) for cable structures in buildings such as conduits, cable reels, and equipment rooms. The set design parameters, if the design does not meet the specifications, the result may be that the existing conduit cannot accommodate all the cables that need to be installed, and additional conduits must be added, or the conduit has too many bends and there is no connection box, resulting in Difficulty in cable routing, or the use of cable reels and connection boxes that make the length of horizontal cables exceed the requirements of Category 5 cables
3. Integrated wiring grounding
When it comes to the grounding of integrated wiring, many readers and friends feel confused, and they will have the following questions: Why is the twisted pair wiring that is usually carried out not grounded? From this point, it can be seen that many users, even professional network administrators Not sure about grounding in network cabling, let alone its importance. In fact, this is determined by the lack of work experience or the limitation of responsibilities, because they have not conducted integrated wiring at all, if there is, it is only a single network wiring.
1. Grounding type of integrated wiring
Since the integrated wiring is aimed at a whole building or even a building group, its grounding is no longer a single grounding problem, but includes multiple levels of grounding systems. According to the provisions of the grounding and wiring requirements of commercial buildings, the grounding types of the integrated wiring system include six parts: grounding wire, grounding bus, grounding trunk, main grounding bus (general grounding terminal), grounding lead-in and grounding body. These six parts The corresponding installation position can be said to be from high to low (relative to the building), if the level is divided, it is from low to high. However, it should be noted that not all integrated wiring systems must have these 6 types of grounding. The following is a brief introduction according to the layers of the above-mentioned grounding lines.
(1) Ground wire
The ground wire is also commonly referred to as the ground wire, which is a type of grounding at the lowest level connected to the equipment, and is also the most terminal part of the entire grounding system. The grounding wire directly acts on each specific node. The two ends of the grounding wire are respectively connected to the node equipment and the grounding busbar to be introduced below, which is the next higher level of the entire grounding system.
Friends who have experience in copper coaxial cable wiring must still remember that in the copper coaxial cable ring wiring, there is an impedance matching terminal at both ends of each line, and the impedance matching terminal usually requires a metal object connected to the ground (usually a Connect with the computer metal case or metal window), this is the ground, and the line connecting the matching terminal with the computer case or metal window is the ground wire. Of course, although the function of the ground wire introduced here is the same, it is no longer connected to the computer case or metal window, but to a higher-level grounding system. All grounding wires are required to be copper insulated wires (the copper impedance is small, mainly for good grounding), the cross-section should not be less than 4mm2, and tin welding should be used as much as possible. Usually when wiring with shielded twisted pair cables, the grounding of the information socket can be connected to the wiring cabinet on each layer by using the shielding layer of the cable as a grounding wire. When the cables of the integrated wiring are laid through steel pipes or metal trunkings, there is no need for additional grounding. The steel pipes or metal trunkings can play the role of grounding, but they are required to maintain good electrical connections, and they should also have good electrical connections at both ends. ground.
(2) Ground bus
The ground bus is also called the floor ground terminal. As can be seen from its name, it is a common ground terminal specially used in the floor. One end of it should be directly connected to the grounding trunk line to be introduced later, and the other end of course should be connected to the grounding line connected to the distribution frame, distribution cabinet, steel pipe or metal trunking and other facilities on the floor. It belongs to an intermediate level, one level higher than the ground wire described above, and one level lower than the grounding trunk described below.
The ground bus is usually installed side by side with the horizontal wiring system in the floor and is used for the common grounding of the whole floor wiring system. The ground busbar should be copper busbar, and its minimum size should be 6mm (thickness) × 50mm (width), and the length should be determined according to the actual needs of the project. The ground bus should be electroplated with tin to reduce contact resistance (do not hand bond).
(3) Grounding trunk
The grounding trunk is used to centrally connect the grounding busbars on different floors, which is obviously one level higher than the grounding busbars described above. It is used for common grounding between different floors of the same building and is usually installed vertically between different floors. When designing the grounding trunk line, the structural form of the building, the size of the building, the routing and space configuration of the integrated wiring should be fully considered, and it should be coordinated with the laying of the integrated wiring cable trunk. The grounding trunk should be installed in a place protected from physical and mechanical damage, and the water pipes and metal cable shielding layers in the building cannot be used as the grounding trunk. The grounding trunk is preferably protected by a special shielding layer, such as into a steel pipe. When two or more vertical grounding trunks are used in a building, the top layers of the vertical grounding trunks shall be welded with insulated conductors of the same cross-section as the grounding trunks. The grounding trunk line should be an insulated copper core wire, and the minimum cross-section should not be less than 16mm2.
(4) Main grounding bus (general grounding terminal)
The main grounding bus, also known as the "general grounding terminal", is used for the common grounding of the entire building and is one level higher than the grounding trunk above. Generally, each building only needs one main grounding bus, one end of which is connected to the grounding trunk, and the other end is connected to a protector device. It is best to use a special shielding sheath. However, it should be noted that if there is only one grounding trunk in the whole building, this main grounding bus is unnecessary, and the grounding trunk also acts as the main grounding bus. The main grounding bus is used as the transfer point of the grounding trunk line and the equipment grounding line in the integrated wiring grounding system. The main grounding bus should be arranged on a straight path, and the welding wire from the protector to the main grounding bus should not be too long. The grounding lead-in (to be introduced below), the grounding trunk, the grounding wire of the DC distribution panel, all the grounding wires between the outside wire lead-ins, and all the metal frames for the integrated wiring located in the same wiring room as the main grounding busbar should be connected to the main grounding wire. The busbars are well soldered. When the outer wire entry cable is equipped with a shield or a metal protective tube, this shield and metal tube should also be welded to the main grounding bus. The main grounding busbar should be a copper busbar with a minimum section size of 6mm (thickness) × 100mm (width), and the length can be determined according to the actual needs of the project. Like the grounding bus, the main grounding bus should also be electroplated with tin to reduce contact resistance.
(5) Ground lead-in
The ground lead-in refers to the connection between the protector device and the grounding body (to be introduced below), which is relatively easy to understand. In order to achieve a good grounding effect, the grounding lead wire should be made of galvanized flat steel of 40mm (width) × 4mm (thickness) or 50mm (width) × 5mm (thickness). The parts should have measures to prevent mechanical damage, and should not be buried in the same place as the heating pipes.
(6) Grounding body
The grounding body is actually used to play the role of "earth" in ordinary grounding, and is divided into two types: natural grounding body and artificial grounding body. Natural grounding bodies include surface steel bars, pressure steel pipes and gates of reinforced concrete hydraulic structures that are in contact with water all the year round, metal embedded parts of trash racks, and metal bodies left in the ground or in water. The artificial grounding body usually refers to the steel products and copper plate products that are artificially buried in the ground. In the burial of steel products, there are two types of vertically installed grounding bodies and horizontally installed grounding bodies.
The vertical grounding body in the grounding system should be made of hot-dip galvanized steel with a length of not less than 2.5m (the length of the vertical grounding body can also be determined according to the soil quality and geographical conditions of the buried ground net), copper-clad steel, or a new type of grounding electrode. . The distance between vertical grounding bodies should generally be greater than 5m, which can be determined according to the size of the grounding network and the construction situation. The connection of the four corners of the ground grid should be buried with a vertical grounding body. The horizontal grounding body in the grounding system is generally made of hot-dip galvanized flat steel, and the horizontal grounding body should be connected with the vertical grounding body by welding.
The grounding body is generally made of hot-dip galvanized steel or copper. When hot-dip galvanized steel is used, the specifications are as follows.
Steel pipe wall thickness: should not be less than 3.5mm.
Angle steel: should not be less than 50mm × 50mm × 5mm.
Flat steel: should not be less than 40mm × 4mm.
Diameter of round steel: should not be less than 8mm.
When the integrated wiring adopts a separate grounding system, the artificial grounding body is generally used, and the following conditions shall be met.
The distance from the grounding body of the power frequency low-voltage AC power supply system should not be less than 10m.
The distance from the grounding body of the lightning protection system of the building should not be less than 2m.
Ground resistance should not be greater than 40.
When the integrated wiring adopts a joint grounding system, the steel mesh in the building foundation is generally used as the natural grounding body, and its grounding resistance should be less than 1. Joint grounding systems are usually used in practical applications.
2. Precautions
Safety grounding is a large-scale equipotential bonding with the earth potential as the reference potential. In the general concept, grounding refers to grounding, and not connecting to the ground is a violation of the basic requirements of electrical safety. This concept has limitations. For example, electric shock accidents and electrical fires rarely occur during aircraft flight, but the aircraft is not connected to the ground. The reason is that the safety of electricity use in the aircraft does not rely on the ground, but relies on equipotential bonding to ensure that the fuselage potential in the aircraft is reference potential for equipotential bonding. Due to the small range within the aircraft, even in the event of an accidental insulation damage, the potential difference is small, so the electrical safety on the aircraft is effectively guaranteed. People live on the earth, so they often need to be equipotential with the earth, that is, to connect the electrical system and electrical equipment housing with the earth, which is often referred to as "grounding". On the plane, the terminal can be used to connect with the fuselage, and on the earth, the grounding electrode is used as the terminal to connect with it.
The following issues should be paid attention to in the grounding design of the integrated wiring system.
(1) A complete shielding system requires shielding everywhere, and a continuous and complete shielding path can achieve the effect expected by the user. Therefore, if you choose to use a shielded system, in addition to cables, the modules, patch panels and other connectors need to be shielded, supplemented by metal bridges and pipes.
The principle of electrostatic shielding is that after the shield is grounded, the interference current flows into the ground through the outer layer of the shield, so it is very important to properly ground the shield layer. Otherwise, not only will the interference not be reduced, but more interference will be introduced. Metal tin foil is prone to tearing when terminated, so care should be taken not to damage the shield when stripping the wires. The stripping length of the ground wire in the shield should be minimized when terminating, because the shorter the stripping length, the less inductance it will cause and the better the grounding effect. When grounding on site, it is recommended to use a single-point grounding method to avoid voltage loops caused by multi-point grounding.
(2) The wiring equipment end of the shielding layer should be grounded, the user end should be grounded according to the specific situation, and the grounding at both ends should be connected to the same grounding body as much as possible. When there are two different grounding bodies in the grounding system, the root mean square value of the grounding potential difference should not be greater than 1V (effective value).
(3) When the cable enters the building from outside the building, it is easily affected by external factors such as lightning strike, power supply grounding, power supply induced potential or ground potential floating, which requires the use of protectors.
(4) The overvoltage protection device of the integrated wiring system should be a gas discharge tube protector. Because the ceramic shell of the gas discharge tube protector is sealed with two electrodes, there is a discharge gap between them, and is filled with an inert gas. When the potential difference between the two electrodes exceeds 250V AC voltage or 700V lightning surge voltage, the gas discharge tube begins to arc, providing a conductive path between the conductor and the ground electrode.
(5) The overcurrent protection of the integrated wiring system should choose a protector that can reset itself. Because of the various voltages that can appear on the cable, if the connected equipment provides it with a low-resistance path to ground, it will not be sufficient for an overvoltage protector to operate, and the current it generates could damage the equipment or cause a fire.
(6) When designing the grounding system, it should be fully considered that the line has overvoltage or overcurrent protection under any of the following dangerous environments: AC 50Hz voltage over 250V, working voltage over 250V power line contact Ground, large lightning strike, ground potential rises above 250V, etc.
The above introduces some of the main knowledge in the grounding of the integrated wiring system. It seems easy, but it is not easy to implement. In fact, the grounding of the integrated wiring is a system problem, which needs to be considered comprehensively, and should not be considered based on a certain machine, a piece of equipment, or even a floor. Only in this way can the grounding system of the entire wiring system be truly effective.
