Conventional electrical installation engineering is divided into strong current, weak current and fire linkage control system. Laboratory electrical installation engineering is different from conventional installation engineering, In terms of electricity, the capacity of laboratory power supply system varies from several watts to over kilowatts according to the different power consumption of equipment, which may involve three-phase alternating current or use unconventional voltage. The scientific, modern and intelligent laboratory management also puts forward higher requirements for weak current system. 1. High power engineering 1) Cable line engineering (A) Material requirements: The type and specification of the cable must meet the design requirements, and be accompanied by product certificate. It is strictly forbidden to have defects such as twisting and breaking. Cable end should be tight, packaging without corrosion. Metal cable pipe should not be perforated, cracks, significant unevenness and serious corrosion, pipe wall should be smooth without burr. B) Construction quality control: The distance between directly buried cable and building foundation is more than 0.6 m; It is strictly forbidden to lay cables parallel above and below the pipeline; The upper and lower parts of directly buried cables shall be paved with soft soil or sand layer with a thickness of not less than 100mm, and covered with concrete protective plates, and the covering width shall exceed 5 0mm on both sides of the cables. Protective pipes should be added when cables enter buildings, pass through floors and enter walls, and lead to poles and equipment from cable trenches. Protective pipes should be added when the outer surface of walls or roofs are below 2m from the ground. When cable protective steel pipes are used as grounding wires, the grounding wires should be welded firmly. When laying cables, spare lengths can be reserved near the cable terminal head and cable joint. Directly buried cables should still leave a small margin on the total length and be laid in waves. Before making cable terminal heads and joints, check the damp of cable insulation paper and phase connection; The insulation materials used should meet the requirements, the accessories should be complete, and the manufacturing process should be completed at one time. The cable joint shell and the cable metal sheath and armor layer there shall be well grounded. The cable tray shall be installed horizontally, horizontally and vertically, firmly fixed, well grounded and neat in appearance. 2) Piping and in-pipe threading works (A) Material requirements: The piping specifications must meet the design requirements, and the products should have certificates and conform to the national or issued technical standards. The installed conductor must have product certificate, and it is strictly forbidden to have defects such as twisting, dead bending and insulation damage. The rated voltage of insulated conductor should be above 500V. B) Construction quality control: When laying concealed piping, buckling should be minimized, and the clear distance from the surface of pipes buried in walls or concrete should not be less than 15mm. Pipelines entering the floor or distribution box shall be arranged neatly, and the nozzle shall be not less than 50mm away from the foundation surface. Effective anti-blocking measures should be taken for concealed packing boxes and boxes to prevent cement slurry from immersing. When opening holes on boxes and boxes, special opening tools should be used, and gas welding and electric welding are strictly prohibited. There should be no wrinkles, holes and other defects at the bending of the pipeline, the bending degree should not be greater than 10% of the outer diameter of the pipe, the pipe joint should not be located at the bending, and the galvanized steel pipe should not be bent by hot bending to make the galvanized layer fall off. Wires and pipes are concealed in reinforced concrete, which should be laid along steel bars and fixed with steel bars by wire or welding. Bellows laid on steel pipes should be bound on the lower side of steel plates. Plastic pipe laid in brick wall. It shall be protected by plastering with cement mortar not less than M10. There shall be no joints and kinks in the wires in the pipe. Retaining rings shall be installed at the exit of the wires. The joints of the wires shall be connected in the junction box. The insulation tape shall be wrapped evenly and tightly at the joints, and the insulation strength shall not be lower than the original strength. The color of insulated wires on the same road in the same project shall be the same. 3) Installation of electrical lighting appliances and their distribution boxes (panels) (A) Equipment requirements: Lighting fixtures and distribution boxes must have factory certificates, models and specifications, which should meet the design requirements. Accessories and spare parts should be complete without device damage. B) Construction quality control: Decorative lamps embedded in the ceiling are fixed on the special frame, and the power cord should not be close to the lamp shell. Fix the frame of the lampshade, and the edge should be tightly toweled on the ceiling surface. When lamps and lanterns are installed symmetrically, their vertical and horizontal central axes should be on the same straight line, and the deviation should not be greater than 5mm. When lamps and lanterns are installed indoors in rows, the central deviation should not be greater than 5mm. The inside and outside of the distribution box should be clean and tidy, with complete parts and complete paint. Metal box is not allowed to use gas cutting hole, must use special hole tool mechanical hole, installation of distribution box around the edge of the panel should be close to the wall, box and the part of the building contact should be brushed anti-corrosion paint, distribution box installation height, bottom edge from the ground is generally 1. 5m. Distribution box should be marked with the name of the electrical circuit, circuit wiring should be in accordance with the drawings, the wiring is correct, incoming and outgoing lines are arranged neatly, avoid crossing, do not make the terminal board under mechanical pressure. The AC withstand voltage test voltage of voltage transformer, circuit breaker, current transformer, isolating switch and bus in the cabinet shall conform to the regulations. The metal box should be reliably grounded or clinging to zero protection. 4) Installation of lightning protection net and grounding device (A) Material requirements: Lightning-proof down lead and solid parts for floor devices are galvanized products, and the guide section of grounding device meets the specified requirements. B) Construction quality control: Disconnection cards shall be set at 1.5-1.8 m from the ground of the lightning protection downlead for grounding resistance detection, protective pipes shall be set at the exit of the floor, and the roof lightning protection belt and electrical piping shall be welded into a whole. The buried depth of the top surface of the grounding body should not be less than 0.6 m, and the angle steel or steel pipe grounding body should be vertically arranged. In order to reduce the shielding effect of adjacent grounding bodies, the spacing of vertical grounding bodies should not be less than 5m according to the design regulations, the local depth should be more than 1m, the distance between grounding bodies and buildings should not be less than 1.5 m, and the resistance < 12. The connection of grounding body is usually welded, The lap welding length of flat steel should be twice the width of flat steel. On the other hand, the lap welding length of round steel should be more than six times the diameter of round steel. When connecting round steel with flat steel, in order to connect reliably, in addition to welding on both sides of its contact part, it should be welded with arc clips bent from steel strips, and the welding places should be treated with anticorrosion.
