Knkong Electric Co.,Ltd

Professional MV & LV switchgear panel manufacturer and supplier


Safety technical requirements for high and low voltage distribution cabinets and distribution boxes

The distribution box is a large number of parameters in the data. Generally, it constitutes a low-voltage forest. According to electrical wiring, it is required to assemble switchgear, measuring instruments, protective appliances and auxiliary equipment in a closed or semi-enclosed metal cabinet or screen to form low-voltage power distribution. box. During normal operation, the circuit can be turned on or off by means of a manual or automatic switch.

  The distribution box has the characteristics of small size, easy installation, special technical performance, fixed location, unique configuration function, not restricted by the site, universal application, stable and reliable operation, high space utilization, small footprint and environmental protection effect.

   Safety technical requirements for high and low voltage distribution cabinets and distribution boxes

   1. The box material of the distribution box and switch box is generally steel plate, but also insulating plate, but wood material is not suitable.

   2. The electrical box and switch box should be installed upright, firm, and not upside down or skewed. The vertical distance between the bottom of the fixed distribution box and switch box and the ground should be greater than 1.3m and less than or equal to 1.5m; the vertical distance between the bottom of the mobile distribution box and switch box and the ground should be greater than or equal to 0.6m and less than Equal to 1.5m.

   3. It is strictly forbidden to connect the power cord into the high-voltage power distribution cabinet with a plug.

   4. The distance between electric boxes should not be too far. The distance between the distribution box and the switch box should not exceed 30m. The horizontal distance between the switch box and the fixed electrical equipment should not exceed 3m.

   5. Each electrical equipment should have its own dedicated switch box. Each electrical equipment on the construction site should have its own dedicated switch box, and must meet the requirements of "one machine, one gate, one leakage". It is strictly forbidden to directly control two or more electrical equipment (including sockets) with the same switch. A leakage protector must be installed in the switch box, the rated leakage current should not be greater than 30ma, and the leakage action time should not be greater than 0.1s.

   6. In order to ensure safety, all power distribution box doors should be equipped with locks. No other temporary electrical equipment should be hooked up or plugged into the power distribution box and switch box. Sundries are strictly prohibited in the switch box.

7. The color of the outer coating of the distribution box (cabinet) should be electrostatic sprayed according to Party A's requirements. The coating should be firmly attached, uniform in color, and free from wrinkles, peeling, spots, leaking and other undesirable phenomena. The distance is 1 meter. Observed everywhere, there is no obvious chromatic aberration and reflection, and the surface is smooth and clean, and there is no damage such as pits and scratches. Other galvanized parts used in the box (cabinet) should also be free from peeling, spots, plating leakage, rust and other undesirable phenomena, and the appearance quality must meet the same requirements. There must be no debris, dust, etc. in the box (cabinet).

   8. Mechanical requirements for distribution boxes (cabinet).

  The thickness of the steel plate selected for the distribution box body is not less than 1.5mm, and the thickness of the distribution cabinet body is not less than 2.0mm thick cold-rolled steel plate, and the thickness of the steel plate door and steel plate surface is not less than 2.0mm. The thickness of the backplane is not less than 3.0mm. The guide rail must be strong, and the structure of the power distribution cabinet should be complete and firm. At the same time, two receiving ears are welded on the lower left corner and upper right corner of the back of the non-floor power distribution box. The receiving ears are made of 40*4 flat steel with a length of 10cm. The connection method and assembly location of the internal electrical components of the box (cabinet) are reasonable, and the number, size, shape and installation method of the box (cabinet) must meet the requirements of the national standards, atlases, and design drawings. The reserved openings or knock-out holes for the incoming and outgoing lines should have corresponding seals to ensure that the three-level sealing requirements are met after the incoming and outgoing lines are assembled.

The welding and bolt connection of the distribution box (cabinet) should be firm, and the welding seam should be uniform, smooth, without welding skin, welding penetration, pores, etc.; the bolt connection should have flat, spring washers, and exposed threaded buckles 2-5 buckle. The internal parts and edges of the openings of the distribution box (cabinet) should be smooth and free of burrs and cracks. The movable parts of the box (cabinet) are open and flexible. The coating or plating shall not be damaged during the opening and closing process. The opening angle shall not be less than 90 degrees. The door lock shall be concealed. The door lock shall be firm and reliable. Shaking, the door hinge is metal chrome plated. When the length of the door is more than 1.2 meters, three hinges can be installed, and two can be used when the door is less than 1.2 meters. The hinges should have sufficient load-bearing capacity. When the load is four times (not less than 10kg), it is guaranteed not to Produce permanent deformation.

   The gap between the door and the door of the distribution box (cabinet), the door and the shell must be the same, the gap is less than 1mm, and the gap length is greater than 1 meter, the uniform difference is not more than 1.5mm. The nameplate of each distribution box (cabinet) must be made of metal. The nameplate contains at least six items such as product name, model, manufacturer name, main technical parameters, factory number, and production date. The nameplate should be fixed on the visible place of the front panel, the specific position should be beautiful and reasonable, and the fixing requirement should be firm. Boxes and cabinets must be accompanied by main circuit diagrams, system diagrams, schematic diagrams, and secondary control diagrams. The requirements of each parameter in the circuit diagrams are consistent with the actual product, and must be plasticized. Use 2mm thick flame-retardant transparent boards to embed the boxes and cabinet doors. .

9. All boxes (cabinet) should be welded with the main grounding terminal on the box (cabinet) structure, and the main grounding terminal should match the largest grounding conductor in the grounding box (cabinet), and it is required to make specifications at the grounding terminal The grounding terminal symbol of the grounding terminal, and the busbar of the protective grounding system should be yellow-green and marked with PE letters over the entire length. The box (cabinet) should be equipped with a special grounding bolt with a diameter of not less than 6mm connected to the metal foundation. The box (cabinet) metal plate, frame, all movable doors, isolation two-layer board, metal plate with live conductor, door with electrical appliances above 36V, cover plate and other conductive parts must be braided with copper tin strip and box The grounding terminal on the (cabinet) body is reliably connected to ensure the continuity of the non-charged metal parts in the box (cabinet) body and the grounding system.

10. All components in the box (cabinet) should be selected in strict accordance with the contract and the drawings provided by us. If there is any change, we will notify you separately. The auxiliary components that are not indicated on the drawings should be selected from certified manufacturers. Qualified products. The components on all products should be guaranteed to meet the product performance requirements. The manufacturer shall provide the certificate of origin of the components, the qualification of the supplier, the specifications and models, the breaking capacity of the circuit breaker, and the certification documents of the electromagnetic leakage protector. The installation of components in the box (cabinet) should be tightened, and there should be no slipping or damage to the coating. Anti-loosening measures and complete fasteners should be provided.

  11. Protection requirements for power distribution cabinets; power distribution boxes (cabinet) are required to be able to operate under the conditions of third-level pollution, that is, the protection level of the power distribution cabinet reaches IP3X. All steel plates and section steels used in the box body must be degreasing, derusting and phosphating treatment before spraying, and other metal parts must have anti-corrosion ability, otherwise anti-corrosion measures must be taken for treatment.

   All insulation in the distribution cabinet must be a self-extinguishing material. The power distribution cabinet must carry out various electrical performance inspections and experiments in accordance with GB05171-1992 and relevant national regulations and standards, and the manufacturer shall provide the inspection and experiment data and effective inspection and experiment reports to the supervision of Party A. After the equipment enters the site, the handover experiment shall be carried out in accordance with the electrical equipment installation engineering electrical equipment handover experiment standard (GB50150), and the experiment can be accepted after passing the test. The electrical performance of other distribution cabinets not mentioned should be able to meet the "Code for Quality Acceptance of Building Electrical Engineering"

   GB50303-2002, "Code for Construction and Acceptance of Low-Voltage Electrical Appliances in Electrical Installation Engineering" GB50254-1996, "Basic Experimental Methods of Low-Voltage Switchgear" GB9466-1997 and other relevant national codes and standards.

  12. Nameplates and various signs; all provided nameplates, instructions, and warning signs must be in Chinese. The content of the nameplate should comply with relevant national regulations, and its material should be a corrosion-resistant and wear-resistant metal material, and it must be firmly attached to a prominent position of the equipment.

Knkong Electric

Date:2020-09-01 14:23

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