Since the reform and opening up, China has conducted extensive technical exchanges with the international community, and many advanced new products and technologies have continuously entered the construction market in China, which has made the building electrical industry step onto a new stage. However, the development of building electrical technology has not changed the problems existing in building electrical installation engineering. This paper mainly considers the common problems in building electrical installation engineering and their solutions. Since the reform and opening-up, China has conducted extensive technical exchanges with the international community, and many advanced new products and technologies have continuously entered China's construction market, which has made the building electrical industry step onto a new stage. However, the development of building electrical technology has not changed the problems existing in building electrical installation engineering. This paper mainly considers the common problems in building electrical installation engineering and their solutions. Keywords: building electrical installation project; Frequently asked questions; The solution is that the building electrical installation project develops rapidly with the vigorous development of the construction industry. Because electrical installation runs through the whole construction process and even the whole use period after the project delivery, the quality of electrical engineering is related to the quality of the whole building. In recent years, the sustained development of the national economy has brought great vitality to the development of the construction industry, but at the same time, some new problems have emerged, which has brought a lot of inconvenience to people's lives. 1 Frequently Asked Questions in Building Electrical Installation Engineering 1. 1 Main Electrical Equipment and Materials Problems ① The conductor has high resistivity, low melting point, poor mechanical properties, poor insulation, large temperature coefficient, large temperature coefficient and insufficient size; ② Cable has low withstand voltage, low insulation resistance, poor corrosion resistance and low temperature resistance. There are many internal joints, and the tightness between insulation layer and wire core is poor; ③ The appearance of power supply, lighting and socket box is poor, the geometric dimensions can not meet the requirements, and the thickness of steel plate and plastic shell is not enough, which affects the strength of the box and the corrosion resistance can not meet the requirements; ④ The conductive values of switches and sockets are inconsistent with the nominal values, the conductive metal sheet is inelastic, poor in contact, easy to generate heat, unable to meet the safety requirements, and the plastic products have low flame retardancy and temperature resistance and poor safety performance; (5) Lamps and light sources are shoddy, with poor mechanical strength, poor rust and corrosion resistance and short service life; ⑥ All kinds of wires and tubes have thin walls, poor strength, unqualified galvanized coating quality and poor folding resistance. 1.2 lightning protection and grounding problems There are defects such as slag inclusion, flash, virtual welding, bite and incomplete penetration at the lap joint of down lead, equalizing ring and lightning protection belt; Welding slag is not knocked off, and the welding place of lightning protection belt is not brushed with antirust paint; Using rebar instead of round steel as lap reinforcement; Directly use butt welding main reinforcement as lightning protection lead. 1.3 distribution pipe laying problems ① Thin-walled pipes replace thick-walled pipes, black iron pipes replace galvanized pipes, and PVC pipes replace metal pipes; ② The bending radius of the threading pipe is too small, which leads to bending, shrinkage and wrinkling, and even "dead bending" in severe cases. Transition box is not set as required for pipeline turning; (3) The burr of the metal nozzle is not treated, but directly butt welded. There is no jumper steel bar welded at the threaded joint and when passing through the intermediate junction box, or the welding length is not enough, so the phenomenon of "spot welding" and pipe penetration welding is serious. Galvanized pipe and thin-walled steel pipe are welded instead of threaded connection; (4) The steel pipe is grounded or not firmly; ⑤ The buried depth of pipelines is not enough, and there are too many overlapping pipelines on precast slabs, which affects civil construction. The pipes in the cast-in-place slab are concentrated into bundles, which affects the structural safety; ⑥ Pipes pass through structural expansion joints and settlement joints without passing through boxes, leaving hidden dangers; ⑦ The exposed and concealed pipes are not put into the box and squeezed into bundles, the outcrop length is inappropriate, the steel pipes are not wrapped with wires, and the PVC pipes are not locked.

1.4, thin-walled copper tube is used instead of thick-walled copper tube to solve the problem of embedding outdoor water inlet pipe; The buried depth is not enough, and the position deviation is large; The elbow is bent by electric welding, and the upper wall pipe is connected with the horizontal household pipe network at 90 degrees by electric welding; The entrance pipeline and basement exterior wall are not well waterproof. 2 Cause analysis of common problems in building electrical installation engineering (1) The electrical market is chaotic, and there are many fake and shoddy products and unlicensed products. Procurement personnel have poor ability to distinguish between true and false, and the control is not strict; (2) The operators have a weak sense of responsibility and are not skilled in welding technology. Most of them are all-round welders in electrician class, and their butt welding operation skills are poor; The site construction administrator failed to implement the relevant provisions of the national construction and acceptance standard GB50 169 2 Grounding Device; (3) The construction personnel are not familiar with the construction specifications, or have not received professional training, and their skills are not very good; The operation is not serious and responsible, convenient and fast, and the requirements for supervision engineers and site management personnel are not strict, and the supervision is not enough; (4) Material buyers are not familiar with national norms and standards when purchasing, and some construction units deliberately confuse them to reduce costs; The construction manager is not strict or afraid to object to the contractor's intentional violation of regulations, and does not resolutely implement the norms and standards. 3 solutions to common problems in building electrical installation engineering 3. 1 electrical equipment materials ① After the electrical equipment materials enter the site, the storekeeper should cooperate with the supervision engineer to check whether the freight yard meets the specification requirements and whether the model, specifications and performance parameters of the equipment materials are in line with the design; (2) The main materials shall have factory certificate or quality certificate, etc. In case of doubt about the quality of materials, samples should be sealed on site and handed over to local qualified testing departments for inspection in time. Only after passing the test can they enter the site and put into use. 3.2 Strengthen the welder's lightning protection and grounding skills training, and require the lap weld to be full, flat and uniform, especially for difficult welding such as vertical welding and overhead welding. Enhance the sense of responsibility of managers and welders, repair unqualified welds in time, knock off welding slag in time and brush anti-rust paint. According to GB50 1692 Code for Construction and Acceptance of Grounding Devices in Electrical Equipment Installation Engineering, the lightning protection downlead is connected by lap welding, and the lap length is 6 times the diameter of round steel. Therefore, it is not allowed to use steel bars instead of round steel as lap steel bars. In addition, if the civil construction of the main reinforcement as the down lead is butt welded, a circle of round steel should be added at the butt welded place as required. 3.3 The laying of electric conduit (1) shall be carried out in strict accordance with the design and specifications, and shall be strictly controlled by professional supervision engineers, and construction shall not be carried out if it does not meet the requirements; (2) When processing pipes, it should be understood that when there is only one 90 elbow in the exposed pipe, the bending radius is not less than 4 times the outer diameter of the pipe; 2 When two or three 90 elbows are used, the bending radius is ≥ 6 times the pipe outer diameter; The bending radius of concealed piping is ≥ 6 times of the external diameter of the pipeline; The bending radius of the pipeline buried underground and in concrete is ≥ 10 times the external diameter of the pipeline; (3) Manual pipe benders with different specifications can be used for galvanized pipes and thin-walled steel pipes with an inner diameter of 25 mm or less, and hydraulic pipe benders can be used for steel pipes with an inner diameter of ≥32mm or more. For PVC pipes, spring elbows of different specifications are selected according to the inner diameter, and pipes with inner diameter ≥32mm are simmered. If they are processed in large quantities, they can be heated in any bending oven. After the pipe is bent, the pipe skin will not wrinkle, crack or deteriorate. When PVC is butted, it is recommended to adopt the butt joint method of full material sleeve and stick it firmly; (4) If the piping exceeds the following length, a junction box can be added at an appropriate position (this box is convenient for threading, but wiring is not allowed). Straight line 50m；; 30m, without bending; 20m, a 90 bend; 15m, two 90 bends; 8m, three 90 bends; ⑤ It is forbidden to cut the steel pipe with a pipe cutter. The hacksaw should be flat (not inclined), and the burr at the nozzle should be cleaned with a circular file. Thick-walled pipes with a diameter of ≥40mm should be welded, and it is not allowed to directly weld the pipe mouth. Tubes with a diameter of ≤32mm shall be connected by sleeve threads or sleeve set screws, and shall not be welded. The connector and the intermediate junction box are bridged by a special grounding card; ⑥ Open pipes and concealed pipes must be reliably grounded according to the specification requirements. Galvanized pipes and thin-walled pipes entering the distribution box shall be firmly connected with the box body with professional grounding wire cards and double-color BV wires ≥ 2.5 mm When pipes with diameters ≥40mm enter the distribution box, they can be fixed on the box body by spot welding, and pay attention to rust prevention and corrosion prevention; ⑦ The pipeline is buried in the wall or underground, and the outer surface of the pipeline is ≥20mm or more away from the wall and the ground, so as to ensure that the wall and the ground do not crack along the pipeline. When laying pipes on precast slabs, try to avoid crossing. When the number of 20mm pipes exceeds the specified number, 1 16mm pipes can be laid side by side. Pipe laying in cast-in-place floor slab is forbidden to be laid in bundles, and should be laid in rows at intervals to reduce the impact on floor slab structure; ⑧ Pipes passing through expansion joints and settlement joints shall be constructed according to the design requirements, and the transition box (box) shall be placed flat and firm; Pet-name ruby open pipe, concealed pipe into the box, into the box to straight. If the outer diameter of the pipe is consistent with the reserved hole of the box, it should be used as much as possible. If the diameter of the pipe is smaller than the hole of the box, a drill should be used to open the hole. If the pipe diameter is larger than the box hole, it should be enlarged on the basis of the box hole. It is forbidden to drill holes by gas cutting or electric welding. More pipes should be discharged into the box at appropriate intervals. Tube into the box length 3-5mm, neatly arranged. 3.4 For outdoor and indoor embedded pipes, thick-walled copper pipes or PVC pipes that meet the requirements must be used for indoor embedded pipes. Strengthen coordination and cooperation with civil engineering and other related majors, clarify the elevation of outdoor floor, ensure that the buried depth of embedded pipes is not less than 0.7m ... Strengthen the education of relevant laws and regulations for contract team leaders and material buyers, and the supervisors should strictly implement the provisions on the inspection of materials entering the site to plug loopholes. The elbow on the upper wall of the embedded steel pipe must be bent by a pipe bender, and welding and welding bending are not allowed. After bending, there should be no cracks and obvious dents in the steel pipe. The bending procedure should not be greater than 10% of the outer diameter of the pipe, and the bending radius should not be less than the minimum allowable bending radius of the cable. Do a good job in waterproof treatment, and ask waterproof professionals to give on-site guidance or waterproof professional teams to do waterproof treatment. Refer to [1] Sang Hui. Talking about several common problems in building electrical installation and construction [J]. Journal of Mudanjiang University, 2004, 13 (3): 63-64. [2] Yang. Common problems in building electrical installation and preventive measures [J]. China Architecture, 2006.

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