Strong electric weak wiring needs to be separated? What are the precautions for wiring?

The concept of strong current is that there is no specific boundary between voltage and current. Electronic people are used to being divided into two parts: strong electricity (electricity) and weak electricity (information). The two are both related and different. In general, the object of processing a strong electric power is energy (electricity). Its characteristics are high voltage, large current, large power, and low frequency. The main consideration is to reduce losses and improve efficiency.

The object of weak current processing is mainly information, that is, information transmission and control. Its characteristics are low voltage, low current, low power, and high frequency. The main consideration is the effect of information transmission, such as the fidelity, speed, and speed of information transmission. Breadth and reliability. In general, weak current projects include television engineering, communications engineering, fire engineering, security engineering, imaging engineering, etc., and integrated wiring works for the above-mentioned projects.

First, strong electric weak distance wiring requirements

With the advent of technological development and the era of intelligent architecture, weak current projects have received more and more attention. The weaker friends all know that there is a requirement for strong and weak electricity wiring distances. Why should the weak electrical wiring be separated?

This is because there is a magnetic field around strong electricity. If the distance between strong and weak electricity is too short, it will affect the signal of weak electricity. The concrete manifestation is: If it is a TV line, the signal will not be very clear; if it is a telephone line, the phone will Noise occurs; if it is a network cable, network transmission speed will be affected and so on.

Therefore, in the strong and weak electrical wiring, we must follow the strong electrical weak wiring distance requirements:

1. User cables must not be routed together with (bundle) high voltage (AC>1000V, DC>1500V) cables. The terminal of the communication cable and the terminal of the high-voltage cable are separated by a minimum of 450 mm.

2. User cables are generally not to be routed (bundled) with low voltage (AC <1000V, DC <1500V) wires. The terminal of the communication cable and the terminal of the low-voltage cable (in the case of a firm spacer) are separated by a minimum of 150 mm.

3, the user cable can be allowed with the ultra-low voltage (AC <42.4V, DC <60V) wires together (bundled) wiring, and the terminal does not require intervals.

4. The user cable should be separated from some harmful equipment (such as lightning arresters, corrosive fluids, objects with a temperature exceeding 60°C, etc.), and the distance between them must not be less than 150mm.

5, separation of power cable and user cable wiring see the following figure.

6. The separation of noise prevention when the low voltage cable crosses the communication cable is shown in the figure below.

Second, strong electricity interference with weak electricity

When the grid is operating normally, in the absence of a single-phase earth fault, there is generally no problem of electromagnetic interference caused by strong electricity. However, when a single-phase ground fault occurs in the power grid operation, different neutral point grounding grids will have significantly different levels of electromagnetic interference on the weak current system. This indicates that the neutral point grounding mode of the grid and its interference with the communication system There is a close connection.

If a single-phase earth fault occurs during operation of the power grid, a large ground current will be generated at the ground point. This current will cause interference to the communication system through electromagnetic coupling, electrostatic coupling, and ground current conduction, etc., and the degree of interference will increase with the ground current. Size and change. Its main manifestations are: audio interference, power frequency interference, contact interference and vertical potential.

When a single-phase earth fault occurs in the power grid, if there is a parallel direction between the power line and the communication line, the induced voltage generated by the electromagnetic coupling will cause interference to the parallel-oriented communication system; or when the power line conductor is disconnected after one phase and two phases are directly connected to the communication. On the line, the contact with the wire leads to interference with the communication system; or the displacement of the neutral point during the operation of the power grid generates a large displacement voltage, which causes interference effects on the communication system through capacitive coupling.

The harm caused by strong electricity to weak currents is as follows: The light affects the quality, the noise in the telephone circuit increases, the information distortion and the bit error rate increase, and the severe cases endanger the communication equipment and personal safety. Such as communication equipment insulation breakdown, the engine room fire, casualties and navigation command signal disorder or misbehavior resulting in accidents and other accidents.

Third, strong electric weak wiring considerations

1. The circuit design and layout stage is based on the principles of strong electric power, weak electric power, and horizontal and vertical, which can avoid cross-cutting during construction and affect the use and appearance.

2. The groove depth of each line should always be 10mm in line with the pipe diameter used.

3. When selecting the circuit wiring, it is necessary to pay attention to the maximum current that the wire can allow to pass, and to avoid overheating and short circuit of the power equipment. Normal lighting, sockets use 2.5mm2, air conditioning circuit uses 4mm2.

4, the laying of dark lines need to be equipped with flame-retardant PVC pipe, the length of the wire is more than 15m or there are more than two corners when wiring, you need to increase the cable box.

5, the PVC pipe laid only after the uniform wiring, the same circuit of the same wire placed in the same pipe, the total number is best not more than 8, the total cross-sectional area of ​​the cable is less than 40% of the pipe cross-sectional area.

6, strong and weak electricity does not penetrate the same pipe, separate wiring, power cord socket and TV line and other weak electrical socket distance should be greater than 500mm.

7. The distance between the electric wires and the heating pipes, hot water pipes, and gas pipes in the home must be more than 300mm, and the distance is more than 100mm.

8, the power socket should pay attention to the left is the zero line, the right is the phase line, three holes above the grounding line.

9. If there is a chandelier installed and the weight is more than 3kg, it is necessary to install the burying lamp in the ceiling and then install the chandelier.

10. The socket panel heights of the power supply, telephone and television in the same space should be the same, with a difference of no more than 5mm.

11, the height of each socket should be changed according to the situation, the power outlet is preferably 300mm, flat switch board is best from the ground is 1300mm, air conditioning outlet from the ground 1900mm, the best kitchen 950mm, washing machine is used 1000mm, TV 650mm .

12. The resistance between the wire and the wire should be greater than 0.5MΩ.

13, strong electricity should have a separate power distribution box, there is leakage protection.

14. After installing switches, panels, sockets, and lamps, pay attention to cleaning. It is best to install them before the last application of latex paint.