Distribution box is the total control of our daily electricity, is a very essential electrical equipment, if there are some security risks, we can deal with it in time, and then introduce the distribution box wiring method, installation method and size determination for your reference.

(1) Wiring method of distribution box

1) The general power distribution box wire is A five-wire system, that is, a, B, C three phase lines (the general color is yellow, green and red), one zero line (color light blue), one ground line (color yellow with green stripes). Line out as needed.

① 220V load generally takes one phase line, one neutral line, and one ground line. ② 380V load, (such as 380V AC motor) three-phase full take, and then add ground wire. (A neutral line is also required if the load has local control.) ③ There is a special two-phase 380V AC welding machine, any two-phase line. Add a ground cable. The grounding wire is generally required to be connected, but many occasions (such as the construction site) are not connected. Generally, the incoming line is a three-phase 3-pin circuit breaker, circuit breaker, knife brake or other circuit breaker; Press the neutral wire to the zero terminal block and the ground wire to the ground terminal block. There are also direct use of 4PIN circuit breaker three phase line and neutral line into the same, the ground line pressed to the ground terminal block.

2) According to the load size of the lighting power distribution, one phase line + one neutral line + one ground line can be used; Or the power distribution of 220V as above.

(2) Installation method of distribution box

1) When the electric box is assembled, the distribution box is installed on the wall, and the open bolt (expansion bolt) should be used to fix it. The length of the bolt is generally the sum of the buried depth (75 ~ 150mm), the thickness of the bottom plate, the thickness of the nut and the washer, and the "head margin" of about 5mm. For a small power distribution box, you can also bury wood bricks at the positions of the four corners of the power distribution box or power distribution board, and then use wood screws to secure the power distribution box or power distribution board at the wooden bricks.

2) Dark assembly electric box, distribution box embedded in the wall installation, in the wall should be reserved holes than the distribution box length and width of about 20mm, the reserved depth is the thickness of the distribution box plus the thickness of the inner wall of the hole plaster. When the box is buried with masonry, the box can be fixed with concrete between the box and the wall.

3) The distribution box should be firmly installed, horizontal and vertical, and the vertical deviation should not be greater than 3mm; When concealed, there should be no gap around the distribution box, the edge around the panel should be close to the wall, and the contact part of the box and the building and structure should be coated with anti-corrosion paint.

4) The screw fuse installed in the distribution box should be connected to the terminal of the middle contact, and the load line should be connected to the terminal of the thread. In this way, no electric shock will be obtained during the loading and unloading of the core. Porcelain insert fuses should be installed vertically.

5) The AC, DC or different voltage levels of the power supply in the distribution box should have obvious signs. The lighting distribution box should be equipped with neutral (N) and protection neutral (PE) bus bars. The neutral and protection neutral wires should be connected on the bus bars, and should be numbered.

6) When the wire leads out of the panel, the panel line hole should be smooth without burr, and the metal panel should be equipped with an insulating protective cover. The metal shell of the distribution box must be reliably grounded (connected to zero).

(3) Classification of distribution box

1) Fixed surface type switchgear, often called switch board or distribution panel. It is an open-type switch cabinet with a panel shield, the front has a protective effect, the back and side can still touch the live part, the protection level is low, can only be used for industrial and mining enterprises with low requirements for power supply continuity and reliability, and can be used for centralized power supply in the substation room.

2) Protective (i.e., closed) switchgear refers to a low-voltage switchgear with all sides closed except the mounting surface. The switch, protection and monitoring control electrical components of this cabinet are installed in a closed enclosure made of steel or insulating materials, reliable wall or off-wall installation. Each circuit in the cabinet can be isolated without isolation measures, or can be isolated by grounding metal plate or insulation board. Usually the door operates with a mechanical interlock with the main switch. In addition, there is a protective table-type switch cabinet (that is, the console), which is equipped with control, measurement, signal and other electrical appliances on the panel. The protected switchgear is mainly used as a power distribution device in the process site.

3) Drawer type switch cabinet. This kind of switch cabinet is made of steel plate closed shell, and the electrical components of the inlet and outlet circuit are installed in the drawer that can be drawn out to form a functional unit that can complete a certain type of power supply task. Between the functional unit and the bus bar or cable, separated by a grounded metal plate or a plastic functional board, forming three areas of the bus bar, functional unit and cable. There are also isolation measures between each functional unit. Drawer type switchgear has high reliability, safety and interchangeability, is a more advanced switchgear, the current production of switchgear, most of the drawer type switchgear. They are suitable for industrial and mining enterprises and high-rise buildings that require high reliability of power supply, as a centralized control distribution center.

4) Power, lighting distribution control box. Mostly closed vertical installation. The protection level of the shell is also different due to the different use occasions. They are mainly used as power distribution devices in the production site of industrial and mining enterprises.

(4) Precautions for distribution box setting

1) The distribution system should be equipped with an indoor general distribution box and an outdoor distribution box, or set up an outdoor general distribution box for each distribution box to implement hierarchical distribution.

2) Power distribution box and lighting distribution box should be set separately, if placed in the same distribution box, power and lighting lines should be set separately.

3) The main distribution box should be located near the power supply area. Distribution boxes should be installed in areas where electrical equipment or loads are relatively concentrated. The distance between the distribution electrical box and the switch box shall not exceed 30m. The horizontal distance between the switch box and the fixed electrical equipment controlled by it should not exceed 3m.

4) For the distribution box that needs to be installed on the ground, it should be installed in a place 50 to 100mm from the ground, and the front side of the distribution box is required to be within the range of 0.8 to 1.2m, without any debris to hinder the power supply, and the surrounding environment is ventilated and dry.

5) The wiring busbar in the box should be set up respectively neutral wire, protective grounding wire, phase wire, to ensure that the various components in the distribution box, instruments and lines are installed firmly, neatly arranged, to facilitate maintenance and maintenance. After the installation is completed, the debris and dust in the box should be removed in time.

6) The electrical appliances in the distribution box should first be installed on the non-metal or wood insulated electrical installation board, and then the whole is fastened in the distribution box box, and the metal plate and the iron distribution box box should be electrically connected.

7) Each electrical equipment should have its own special switch box, must implement the "one machine, one gate, one protection" system, it is strictly prohibited to use the same switching appliance to directly control more than two electrical equipment.

8) The rated leakage action current and rated leakage action time of the two-stage leakage protector in the distribution box and the switch box should be reasonably matched to make it have the function of graded protection.

9) The wood bricks and iron pieces required for the installation of the switchboard need to be buried in advance, and the open-mounted distribution box should be fixed with metal expansion bolts. Wiring should be neatly arranged and tied into bundles, and the moving parts should be fixed.

10) The ratings of various switching appliances should be adapted to the ratings of their control electrical equipment.

11) When the construction site stops working for more than one hour, the power switch box should be powered off and locked.

12) When inspecting and maintaining the distribution box and switch box, the corresponding power switch in the previous level must be switched off, and the power failure sign must be hung, and live operation is strictly prohibited.

(5) Determine the size of the distribution box

1) When the electric box is only a lighting box or small power, when the incoming line is less than 10 square, if the switch number is less than 20, the switch width size is added up to 20MM on each side for the width of the electric box, the height is the switch height plus 40MM, the depth is the maximum depth of the switch plus 10MM.

2) When the electric box is only a lighting box or small power, when the incoming line is less than 10 square, if the switch number is greater than 20, this time the electric box needs to be arranged for two rows of switches, the switch width size added up to 40MM on each side is the width of the electric box, the height is the switch height plus 40MM, the depth is the maximum depth of the switch plus 10MM.

3) When the electric box is only a lighting box or small power, the incoming line is less than 10 square, if the incoming line switch needs a separate row, the switch width size added up to 20MM on each side is the width of the electric box, the height of the switch height added to the line switch height added 40MM, the depth of the switch maximum depth added 10MM.

4) When the power box is the power box, or the power lighting box, the algorithm is basically the same as above, but when the incoming line is greater than 10 square, the bending radius of the incoming line should be considered, and the wiring of the switch should be considered when two rows of switches are arranged.

Of course, the size of the electric box is not conclusive, to consider the actual installation, to see the actual wiring diagram and consider how to arrange the switch layout of the first-level switch. If all the circuit breakers are determined according to the number of bits (18mm each), the PZ series distribution box has a fixed size, the circuit exceeds 80 bits can be identified on the drawing Party to determine (words), the equipment control box identification equipment comes with, the incoming line is greater than 185mm², and the output is greater than 2 as far as possible.