Precautions for installation of distribution box

The distribution box is an essential power distribution device in modern homes and businesses, and its installation and use are crucial to the safety and stability of the power system.

But when it comes to the taboos in the installation of distribution boxes, most of the electrical personnel must have a little understanding. The installation of lighting distribution boxes faces new challenges due to the variety of building electrical appliances. Therefore, the installation of lighting distribution boxes is easy. Various problems arise.

Therefore, when installing lighting distribution boxes, we need to understand what are the problems that are prone to occur, and what taboos need to be followed, so as to ensure the safety of electrical equipment. To ensure safety and reliability, the following article will introduce you in detail. After reading the article, I hope it can bring you some help in your work.

Precautions for installation of distribution box

The lighting distribution box (board) was not inspected when it entered the site

Consequences: The lighting distribution box (board) has not been inspected when it enters the site, and it is often discovered after installation: the second-layer board has no special grounding bolts, the cross-section of the protective ground wire is small, and the openable door equipped with electrical appliances does not use bare copper flexible wires Reliable connection with the metal frame, the connection between the wire and the appliance is not firm, there is a reverse loop phenomenon, the screw nut does not use galvanized parts, the diameter of the wire does not meet the requirements, there is no color code identification, there is no card cabinet and electrical circuit diagram, the layout and interval of the appliance Unreasonable, N and PE terminal blocks are not set. Modifying the delayed construction period also affects the quality.

Measures: First of all, when processing and ordering, we should put forward the technical requirements that meet the design and specification standards to the manufacturer, and ask the manufacturer to make samples, and then re-produce after passing the acceptance; and check and accept the products strictly according to the design and specification standards when they enter the market. , and then proceed to installation after confirmation.

Precautions for installation of distribution box

The lighting distribution box (board) is made of wood material without flame retardant treatment

Consequences: If the lighting distribution box (board) is used in a humid and dusty place, the wooden one is prone to mildew and leakage; in addition, the wooden box (board) without flame retardant treatment is easy to cause fire, which is an unsafe hidden danger.

Measures: In order to ensure safe use, it is required that the lighting distribution box (board) should not be made of combustible materials. Even in a dry and dust-free place, the wooden distribution box (board) used should be flame retardant before use.

The elevation does not meet the requirements, and the edges around the panel are not close to the wall

Consequences: The installation elevation of the lighting distribution box (board) does not meet the requirements, the installation is not firm, and the box body is not vertical.

Measures: The elevation should meet the design requirements. If the design does not specify, the height from the bottom edge of the lighting distribution box to the ground should be 1.5m. The height from the bottom edge of the lighting distribution board to the ground should be 1.8m. The lighting distribution box (board) should be installed firmly, and the allowable deviation of the installation verticality should not be greater than 3mm. During installation, there should be no gaps around the distribution box, the edges around the panel should be close to the wall, and the contact between the box and buildings and structures Apply anti-corrosion paint.

The lines in the lighting distribution box (board) are messy and not bundled

Consequences: The lines in the lighting distribution box (board) are messy, and the two-layer board in the box is tightly pressed against the nozzle, which affects the entry of the wires into the box. If it is squeezed in, the insulation of the wires will be damaged after a long time, and it is easy to cause a short circuit. And make maintenance inconvenient, affect perception.

Measures: When metal boxes are used for lighting distribution boxes, anti-rust and anti-corrosion treatment should be done. The outlet holes in the box cannot be opened by electric welding, but one hole for each tube, and the metal box holes should be covered with protective sleeves before threading. Lines should be arranged neatly, and the position of the tubes entering the box should be reasonably arranged. Do not let the second-layer board press the tubes tightly.

No N and PE bus bars are installed in the lighting distribution box (board)

Consequences: N and PE bus bars are not installed in the lighting distribution box (board), and the safe operation of the line cannot be guaranteed.

Measures: In the lighting distribution box (board), the neutral wire (N wire) and the protective ground wire (PE wire) busbar should be set respectively, and the neutral wire and the protective ground wire should be connected on the busbar without twisting There is a number.

The wiring of the spiral fuse installed in the lighting distribution box (board) is not correct

Consequences: The wiring of the spiral fuse installed in the lighting distribution box (board) is incorrect, and the power cord is connected to the threaded terminal, which affects the replacement of the fuse core, and improper operation may easily cause electric shock accidents.

Measures: In order to ensure safety, the power line of the spiral fuse installed in the lighting distribution box (board) should be connected to the terminal of the intermediate contact, and the load line should be connected to the threaded terminal.

The protection line is not well done, and the wire diameter does not meet the requirements

Consequences: The protection wires of the lighting distribution box (board) are not arranged from the terminals, but are connected in series by using the box frame, the wire diameter is not set as required, and the devices with super-safe voltage on the distribution box door are not equipped with protective ground wires. It is easy to cause safety accidents.

Measures: According to the requirements of the specification, the protective ground wire bus bar should be installed in the lighting distribution box (board), and the protective ground wire should be connected on the bus bar. The cross-sectional area of the protective ground wire should not be smaller than the cross-sectional area of the largest lead wire from the power supply to the associated electrical appliance; it should also be selected in accordance with relevant regulations. The grounding on the distribution box (board) should be firm and good, and there must be an anti-loosening device.

For the openable door equipped with electrical equipment exceeding 50V, the movable panel shall be reliably connected to a well-grounded metal frame with bare copper flexible wires. The cross-sectional area of the bare copper soft wire should also be selected according to the regulations. Metal boxes and box bodies with a wall thickness less than 2.5mm should not be used as spans for pipelines. Ground wire and protective earth wire crimping point of electrical appliance. The cross-sectional area of the protective ground wire is according to the cross-sectional area of the protective ground wire (mm2), the cross-sectional area S of the phase conductor of the device, and the corresponding cross-sectional area of the protective conductor Sp

S≦16 SP=S

16≦S≦35 SP=16

S＞35 SP =S/2

Unit mm2

The gate in the lighting distribution box (board) does not indicate the name of the circuit

Consequences: The brakes in the lighting distribution box (board) are not marked with the name of the circuit, which brings inconvenience to use and maintenance. If the brakes should not be closed by mistake, it is easy to cause safety accidents.

Measures: Generally, according to the standard requirements, the wiring system diagram should be pasted inside the door of the lighting distribution box (board), and the name of the circuit should be marked on the gate, especially if there is AC, DC or different wiring in the lighting distribution box (board). Grade power supply should have obvious signs. It brings convenience and safety to the work of users and maintenance personnel.

The installation of electrical appliances and meters is not firm, and the spacing does not meet the requirements

Consequences: The installation of electrical appliances and instruments in the lighting distribution box (board) is not firm, uneven, and the spacing is not enough, which affects the safety of use.

Measures: The electrical appliances and instruments on the lighting distribution box (board) should be installed firmly, flat and tidy, with uniform spacing, no loose copper terminals, flexible opening and closing, and complete parts. The arrangement spacing of electrical appliances and instruments shall meet the requirements of the standard.

The wires in the lighting distribution box (board) are not threaded according to the color code

Consequences: If you do not thread the wires according to the color code, when using a single-phase circuit, it is difficult to balance the load because it is not easy to identify the three-phase power supply, resulting in serious three-phase imbalance. It is easy to mix the phase sequence when wiring, and it is difficult to grasp the direction of rotation when some equipment needs to be fixed for operation.

Measures: In order to ensure safety and facilitate construction, the wires in the lighting distribution box (board) can pass through the trunk line in the tube according to the regulations without color separation, but the section of the trunk line circuit from the mouth of the line pipe to the main switch of the distribution box (board) and each The electrical branches shall be color-coded according to the requirements of the color code. In this way, when a single-phase circuit is used, its load can be better balanced, and when a three-phase power supply is used, it must be wired in phase sequence to ensure the normal operation of the equipment.

Removable metal plate, not connected to the protective earth system

Consequences: The detachable metal plates in the lighting distribution box are equipped with various electrical accessories. If the protective ground wire is not connected, it is easy to cause electric shock accidents.

Measures: The detachable metal plate in the lighting distribution box should have reliable grounding protection, so it is required that the metal plate should be equipped with a non-detachable special grounding screw, and the protective ground wire should be effectively connected to it. The wire diameter of the protective ground wire should be matched according to the specifications and standards to ensure safe use.

Improper location of lighting distribution box in shaft

Consequences: The lighting distribution box is installed in the shaft. Because there are strong and weak currents in the shaft, and the space is very narrow, it is not easy to operate. A little carelessness may easily lead to safety accidents.

Measures: After receiving the drawings, carefully review the drawings. If it is found that the layout of the electrical pipes and boxes in the shaft cannot meet the requirements of the specifications and standards, it should be raised during the design disclosure.

It is generally required that an operation and maintenance distance of not less than 0.8m should be left in front of the lighting distribution box and terminal box in the electrical shaft. And in order to prevent the strong electricity from interfering with the weak electricity, the strong electricity and the weak electricity are respectively arranged on both sides of the shaft or isolation measures are taken.

The wire pipe nozzle in the floor-standing distribution box is too low

Consequences: The nozzles of the wires and pipelines laid in the floor-standing distribution box are too low, which can easily cause accumulated water and sundries to enter the tubes and reduce the insulation strength of the wires.

Measures: The wire protection tube in the floor-standing distribution box should be 50-80mm higher than the base surface of the distribution box. The pipelines should be arranged neatly, and the nozzles should be trumpet-shaped.

Metal accessories are not treated for corrosion protection

Consequences: The metal accessories are not galvanized or anti-corrosion treated, so they are easily corroded and the service life is shortened.

Measures: In order to ensure the quality of the project and prolong the service life, it is required that the metal accessories used in the wiring and electrical installation lighting projects, such as pipe clips, brackets, hooks, pull rings and box (box) bolts, nuts and other ferrous metal accessories, All should be galvanized or coated with anti-corrosion paint.