Electrical engineering quality common common problem summary - Database & Sql Blog Articles

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First, lightning protection grounding does not meet the requirements
1. Phenomenon (l), down conductor, equalizing ring, and lightning protection belt joints have defects such as slag inclusion, welding tumor, virtual welding, biting meat, and insufficient weld seam.
(2) The welding slag does not knock off, and the welding place on the lightning protection belt does not brush anti-rust paint.
(3) Rebar is replaced by rebar instead of round steel.
(4) Directly use the main steel bar welded to the head for lightning protection.
2, the cause analysis (1), the operator's sense of responsibility is not strong, welding technology is not skilled, most of them are multi-face welders in the electrician class, the operation skills of the opposite welding is poor.
(2) The on-site construction manager has insufficient implementation of the national construction and acceptance specifications GB50169 2 "Grounding device".
3, preventive measures (l), strengthen the skills training for welders, requires that the welds in the lap welds are full and even, especially for the welding of difficult welding such as vertical welding and overhead welding.
(2) Enhance the responsibility of management personnel and welders, timely repair welding unqualified welds, and timely knock out the welding slag and brush anti-rust paint.
(3) According to GB50169 2 "Code for Construction and Acceptance of Grounding Devices for Installation of Electrical Installations", the connection of the lightning protection down conductor is lap welding, and the lap length is 6 times the diameter of the round steel. Therefore, rebar is not allowed. Instead of round steel for lap joint reinforcement. In addition, if the main reinforced concrete as the down conductor is welded to the head, the lap joint should be filled in the welded joint.
Second, the outdoor household management pre-treatment does not meet the requirements.
l. Phenomenon (1) Replace the thick-walled steel pipe with a thin-walled copper pipe.
(2) The pre-buried depth is not enough and the position deviation is large.
(3), the corner is welded by electric welding, and the upper wall pipe is connected with the horizontal household pipe network to form a 90° angle.
(4) The waterproof treatment of the household pipe and the underground outdoor wall is not good.
2. Reason analysis (l), material purchasers are not familiar with national norms and standards when purchasing, and some construction units deliberately confuse to reduce costs; construction administrators are not strict or do not dare to object to the contractor’s intentional violations, Resolutely implement norms and standards; supervisors have loopholes in the management of materials entering the market.
(2) Insufficient coordination with civil engineering and other professional teams.
(3), there is no bender or will not use the bender, the responsibility is not strong, and it is convenient to use electric welding to bend.
(4) Workers who are buried in the household pipe do not understand the waterproof technology, and do not ask the waterproof professional to help.
3, preventive measures (l), the household embedded pipe must use thick-walled copper pipe or PVC pipe that meets the requirements (general wall thickness PVC Φ l 14 is 4.5mm or more, Φ56 is 3mm meters).
(2) Strengthen coordination and cooperation with civil engineering and other related majors, clarify the outdoor ground elevation, and ensure that the buried buried depth is not less than 0.7 meters.
(3) Strengthen the education on the relevant regulations of contract team leaders and material purchasers. Supervisors must strictly implement the requirements for materials entry inspection and block loopholes.
(4) The elbow of the upper wall of the pre-buried steel pipe must be bent with a bender, and welding and welding are not allowed to bend. After the steel pipe is bent, there should be no cracks and significant dents. The bending procedure should not be greater than 10% of the outer diameter of the pipe. The bending radius should not be less than the minimum allowable bending radius of the cable to be penetrated.
(5), do waterproof treatment, please waterproof professional on-site guidance or waterproof professional team to do waterproof treatment.
Third, the laying of electric wire tubes (steel pipes, PVC pipes) does not meet the requirements
1. Phenomenon (1), the cable tubes overlap in multiple layers, and the ridges of the steel bars are higher than this.
(2) Two or more wires and tubes are placed next to each other.
(3) The depth of the buried wall of the wire and tube is too shallow, even buried in the powder layer outside the wall. The tube showed dead bends, painful folds, and dents.
(4) The electric wire tube enters the distribution box, and the nozzle is not filled in the box.
The exposure is too long; the nozzle is not flat and the length is different; the nozzle does not need a protective ring; it is not locked and fixed.
(5) When the PVC wire and pipe is pre-buried, the pipe is not blocked by the plug, but the pipe is bent with a clamp.
2, the cause analysis (1), the construction personnel are not familiar with the relevant norms, the work attitude is sloppy, the map is convenient, and is not implemented according to regulations. Construction administrator management is not in place.
(2) The architectural design layout and electrical professional coordination are not enough, resulting in multiple conduits passing through the same narrow plane.
3. Preventive measures (1) Strengthen the quality control of the construction process of on-site construction personnel, and carry out targeted training for workers; management personnel should be familiar with relevant regulations and strictly manage.
(2) Multi-layer overlap of wire and tube generally appears in the public passage of high-rise buildings. When there are more than 6 sets of towers in each floor, it is recommended that the civil works should be decorated with ceilings in the public corridors, so that most of the entrance lines of the electric professional can enter the household directly through the trunks laid on the ceiling. It is also possible to use a thickened public walkway floor to allow a large number of conduits to be concealed. Electrical professional construction personnel should minimize the number of overlapping layers of the line at the same point.
(3) The wire layers cannot be closely attached to each other. If it is difficult to separate them clearly during construction, they can be separated by small cement blocks.
(4), the wire tube is buried in the brick wall, the distance from the surface should not be 15mm, the pipe laying should be (5), the bending radius of the wire pipe (dark burying) should not be less than 10 times the outer diameter of the pipe,
The bending of the pipe should be made with a pipe bender or a sturdy handle to make the bend flat and smooth, without the phenomenon of flat folds and dents.
(6), the wire tube should be leveled into the distribution box, the exposed length is 3-5mm, the pipe mouth should be sheathed and the case should be locked. Enter the wire tube of the floor-standing distribution box, the pipe mouth should be 50-80mm higher than the base surface of the distribution box.
(7) When pre-embedded PVC wire and tube, it is forbidden to clamp and straighten the pipe mouth with pliers, and apply the PVC plug with the pipe diameter to cover the pipe mouth, and tie it tightly with tape.
Fourth, the wiring, connection quality and color code of the wire do not meet the requirements
1. Phenomenon (l), multi-strand wire does not use copper joint, directly made (2), when connected with the terminal of switch, socket and distribution box, several wires are connected to one terminal.
(3), the wire head is bare, the wires are not arranged neatly, and there is no bundled bandage.
(4) The three-phase, neutral (N-line) and ground-protected (PE line) color code of the wire are inconsistent or confusing.
2. Reason analysis (l) The construction personnel are not proficient in the wiring process and technology of the wires.
(2) The material purchaser did not prepare the various conductor colors and quantities required for the construction as required, or the construction management personnel mixed them to save materials.
3. Preventive measures (l) Strengthen the construction personnel's training on standardized learning and skills.
(2), the connection of multiple strands of wire, the application of galvanized copper joint crimping, try not to do the "sheep eye" shape, if done, it should be even tin.
(3) There should be only one wire connection on the terminal and the Terminal Block. If two wires are to be connected, a flat gasket should be added in the middle; no more than three connections are allowed.
(4) The wire layout should be horizontal and vertical. When the wire is stripped, the length of each wire should be kept the same. After the wire is inserted into the terminal, there should be no bare conductor; the copper joint and the wire should be wrapped with insulating tape of the same color as the wire.
(5), material procurement personnel must match the wire of various colors according to the needs of the site.
(6), the construction personnel should clearly distinguish the phase line, the zero line (N line), the grounding protection line (PE line) and the color mark distinction, that is, PA phase - yellow, B phase - green, C phase - red; single It is generally preferred to use red in the phase; light blue or blue for the neutral (N-line) and yellow-green two-color conductor for the grounding protection (PC).
5. The installation and wiring of the distribution box do not meet the requirements.
l. Phenomenon (l), there is a gap between the box and the wall, and the box is not straight.
(2) The mortar and debris in the box are not cleaned up.
(3) The opening of the box shell does not meet the requirements, especially the opening of the hole by electric welding or gas welding, which seriously damages the paint protective layer of the box body and destroys the beauty of the box body.
(4) The grounding power box grounding is not obvious (below the bottom of the box, it is not easy to find), and the repeated grounding conductor cross section is not enough. The wire inside the box is bare, the wiring is not neat, and the wire does not leave a margin.
2. Reason analysis (l) When the cabinet is installed, the coordination with the civil works is not enough. The civil construction joints are not full, and the cabinets are installed without the water level.
(2) Carefully clean the sand debris in the box.
(3) When the "knocking hole" opening of the box does not match the inlet pipe, it must be re-machined by mechanical opening or returned to the manufacturer, or strictly calibrated when ordering, and produced according to the size.
(4) Strengthen inspection and supervision and enhance the responsibility of construction workers.
(5) Thoroughly understand the relevant provisions of the acceptance department regarding grounding. According to the requirements of the power supply department and the municipal quality inspection station, the grounding of the power box and the wires must be clearly exposed, and they cannot be welded or wired under the box. The grounded conductor is in accordance with the specification. When the phase cross section of the device is S≤16mm2, the minimum cross section of the grounding wire is S; when 16<S≤35mm2, the minimum cross section of the grounding wire is 16mm2; when S>35mm2, the minimum cross section of the grounding wire It is S/2.
(6), the thread inside the box should be unified, can not be exposed, the wiring should be neat and beautiful, tied and fixed, the wire should have a certain margin, generally have a margin of 10-5CM in the box.
Sixth, the installation and wiring of the switch and socket box and panel do not meet the requirements
1. Phenomenon (1), the wire box is pre-buried too deep, and the elevation is different; there is a gap between the panel and the wall, and the panel is contaminated with paint and is not straight.
(2), the wire box is left with debris.
(3) The phase line, neutral line and PE protection line of the switch and socket have a series connection phenomenon.
(4) The wire ends of the switches and sockets are bare, the fixing bolts are loose, and the remaining wires in the box are insufficient.
2, the reason analysis (1), the embedded wire box is not firmly fixed, the template is expanded, the coordinates are not accurate when installed.
(2) The construction personnel's sense of responsibility is not strong, and they have insufficient understanding of the importance of the safety of the use of electrical appliances.
(3) There are unreasonable ideas for saving materials.
3, preventive measures (1), closely cooperate with the civil engineering profession, accurately and firmly fixed the line box; when the pre-embedded line box is too deep, a wire box should be installed. When installing the panel, it should be horizontal and vertical, and the level should be adjusted by the level to ensure the uniformity of the installation height. In addition, after installing the panel, it is necessary to fill up the seams, no gaps are allowed, and the panel is cleaned and protected.
(2) Strengthen management supervision and ensure that the phase line, neutral line and PE protection line in the switch and socket cannot be connected in series, first clean the mortar in the box.
(3) Fixed size when stripping, ensure that the thread head is neat and uniform, and the wire head is not exposed after installation; at the same time, in order to firmly press the wire, the single core wire should be twisted into double strands when inserted into the wire hole, and tightened and tightened with screws.
(4), the wire in the switch and socket box should have a certain margin, generally 100-150mm is appropriate; it is necessary to resolutely put an end to unreasonable material saving.
Seven, the installation of lamps and ceiling fans does not meet the requirements.
1. Phenomenon (l), the lamp position is installed offset, not at the center point.
(2) The horizontalness and straightness deviation of the rows of lamps are large.
(3), the chain of the fluorescent chain of the hanging chain is not parallel, and the lead wire is not edited yet.
(4) The hook of the ceiling fan is processed by rebar, which is poorly formed; the bell jar does not absorb the ceiling, and the junction box is exposed.
(5), the iron plate of the balcony lamp chassis is large and rusty.
(6), the ceiling of the ceiling is very large, not neat.
2. Reason analysis (l) When the lamp box is embedded, the position is wrong, there is a deviation, and no remedial measures are taken when installing the lamp.
(2) The construction man's curse is not strong, and he is not familiar with the current construction and acceptance specifications and quality inspection and evaluation standards.
(3) When the purchaser purchases the lamp, he is willing to make a declaration and disregard the quality;
(4) When the opening of the downlight is not fixed, the size of the nationality and the diameter of the round hole are not uniform.
3. Precautionary measures (l) Before installing the luminaire, carefully locate the center point and correct the deviation in time.
(2) According to the standard French, the deviation of installation of rows of lamps should not exceed 5mm. Therefore, in the construction, the cable positioning is required, so that the lamps are in the vertical, horizontal, oblique and main low levels.
(3) The slings of fluorescent lamps shall be straight to each other, and shall not appear in a splayed shape. The conductors shall be spliced ​​together with the slings.
(4) When pre-embedded ceiling fan hooks, the galvanized round steel not less than Ф8 is fixed with the steel bars in the plate, and the rebar is not allowed. The hooks should be formed in the same shape and brushed with anti-rust paint. The bell of the ceiling fan can ceiling and cover the hook and junction box. The rows of ceiling fans should be in a straight line with a deviation of ≤5mm.
(5) The thickness of the bottom box iron plate of the balcony lamp is ≥0.5mm, and the paint surface is even and smooth, which can play a good role of rust prevention; the glass cover can not be too thin to avoid cracking during installation.
(6) The opening of the downlight of the ceiling should be fixed first. In addition to the requirement of straight, neat and equal, the size of the opening should meet the specifications of the downlight, not too large, to ensure that the outer ring is firm when the downlight is installed. The ground is close to the ceiling and there is no gap.
(7) Construction workers and procurement personnel must conscientiously implement relevant national and local regulations.
Eight, cable, busbar installation does not meet the requirements
l. Phenomenon (l). After the cable is installed, there is no unified listing. The cable is laid in the cable trench and bridge.
(2) In the shaft, the cable hole is not tightly sealed; the bracket for the vertical fixed cable is too small, too soft, and inclined downward.
(3) The cable is not tightly sealed after passing through the household pipe.
(4) The terminal (wire ear) is too large or too small, the wall is too thin, and the connector is broken when it is pressed.
(5) The busbar's plug-in box is not installed straight, and the busbars of each section are too long to be transported and installed.
2, the cause analysis (1), the cable construction unit is not well coordinated, only the cable that you can lay can pass.
(2) It is not well coordinated with the civil construction unit when blocking the strong electric shaft. The construction personnel do not master the technology of sealing.
(3) If the materials fail, the purchaser does not purchase the cable fixing bracket and the terminal (wire ear) according to the standard.
(4) The area reserved for the electrical profession to make strong electric shafts is too small, which makes it difficult to arrange strong electric shafts.
3, preventive measures (1), the cable construction team should be well coordinated, the size of the cable is arranged in the direction and position, after installation, unified use of moisture-proof and anti-corrosion cards listed, indicating the line number and model of each type of sample cable , specifications and starting points. The listing positions are: cable terminal head, corner philosophy, sandwich, both ends of the shaft, and manhole holes in the cable trench.
(2) Use the mixture of hemp and asphalt to block the hole through which the shaft cable passes. When there is an outdoor entrance pipe to the basement, the pipe mouth should be waterproofed. These work need to be closely coordinated with the civil engineering profession. Clean up the site after blocking.
(3) When purchasing materials such as cable round brackets and terminal blocks (wire ears), purchase them in accordance with the specifications. When crimping the joint, the corresponding hydraulic clamp and corresponding kit are selected accurately.
(4) When ordering the busbar, it must be ensured that each busbar should not be larger than each floor; generally not more than 3m, to facilitate the handling and installation in the building.
(5) When the busbars and accessories come into play, it is necessary to strictly follow GBJ149-90 "Code for Construction and Acceptance of Busbar Installations for Electrical Installations" and contract inspection.
(6) When installing the plug-in box, it should be horizontal and vertical, and the contact with the bus bar is reliable and firm.
9. Indoor and outdoor cable trench structures and cable ducts are not in compliance with requirements.
l, phenomenon (1), cable trench and raft bracket installation is not straight, easy to break.
(2), cable trenches, cable ducts are not well drained.
(3) The cable crossing pipe is buried deep enough, and the bell mouth is broken and irregular.
(4), the steel pipe anti-rust anti-corrosion paint is uneven, the sealing is not enough, especially the anti-rust and anti-corrosion in the pipe is not done.
(5) The grounding pole is not straight and loose in the cable trench, and the grid connection with the bypass pipe is not comprehensive, and some pipes are leak welded.
2, the cause analysis (1), civil construction units are not serious construction; ç ¼ bracket prefabricated parts aging or no steel for bone, so that the bearing capacity is not enough.
(2) There is no certain slope at the bottom of the cable trench, and the water collecting pit is not made according to the specifications; the objective conditions on the site do not meet the drainage requirements.
(3) The installation personnel are not responsible for the installation. There are other professional pipes or wells that affect the laying of the cable pipes.
(4) When the tanks are not arranged according to the requirements, the poles are welded one by one. When all the pipes are buried and welded, the conditions are not allowed to be welded one by one, and it is only necessary to weld the number at the bell mouth.
3. Precautionary measures (l) When the civil engineering unit installs the truss bracket, the cable should be leveled and vertical; the distance from the uppermost bracket to the top of the trench is 150mm-200mm, and the distance from the lowest bracket to the bottom of the trench is
50mm-100mm. Qualified ç ¼ brackets should be purchased from qualified manufacturers to ensure sufficient supporting force; steel brackets should be protected against rust and corrosion.
(2) According to the relevant provisions of GB50054-95 "Design Specification for Low-Voltage Power Distribution", the slope of the drainage ditch at the bottom of the cable trench shall not be less than 0.5%, and a water collecting pit shall be set up, and the accumulated water shall be directly discharged into the sewer; The relevant specifications of the building can also refer to the "Atlas of Building Electrical Installation Engineering" edited by Lu Guang in the second edition of the first volume of 5.35 "General Practice for Cable Manholes". When the puddles are far away from rainwater wells or rainwater When the elevation of the well is higher than the bottom of the cable trench, the corresponding drainage system should be adjusted accordingly. Therefore, the relevant elevation of each major should be carefully compared when the outdoor integrated pipe network diagram is reviewed.
(3) The bell mouth is required to be even and tidy without cracks. When the cable tube is pre-buried, the depth should be less than 0.7m. If the objective conditions are not met, the pipe should be covered with cement mortar to ensure that the pipe is not crushed.
(4), the cable pipe should use thick-walled copper pipe, both inside and outside should be painted anti-corrosion anti-rust paint or asphalt, the paint surface should be even; especially at the welding mouth, it needs to be rust-proof. When the two cable tubes are butted, the inner nozzles should be aligned, and then the short sleeves (length not less than 2.2 times the outer diameter of the cable tubes) should be added and welded firmly and sealingly.
(5) The grounding shoulder steel in the cable trench should be installed firmly. Generally, a fixed terminal is installed every 0.5-1.5m, and the height of the high groove bottom is 250mm-300mm. When passing through the pipe, it must be overlapped with each steel pipe, and the lap joint should be treated with anti-corrosion and anti-rust treatment. In order to ensure that each steel pipe can be reliably connected with the grounding pole, it is welded one by one when the pipe is buried, and it is not allowed to be welded after the pipe is buried.
10. Installation of street lamps, lawn lamps, garden lamps and floor lamps does not meet the requirements.
1. Phenomenon (1), the lamp post is lacquered, rusted, loose.
(2) The grounding installation does not meet the requirements, even without a grounding wire.
(3) The lampshade is too thin and is easy to break or fall off.
(4), the lamp wattage of the lawn lamp and the floor lamp is too large, the temperature of the lampshade is too high when used, and it is easy to burn people; or the corner of the lampshade is sharp and easy to cut.
2. Reason analysis (1) There is no strict requirement when purchasing lamps; the anti-rust layer is not well done; the glass or plastic of the lampshade is not strong enough; the bolts of the fixed lamp holder do not match and are difficult to fix.
(2) Designing only considers illuminance, negligence may cause harm to pedestrians, especially children.
(3) The construction personnel do not conscientiously implement the norms and have insufficient understanding of the importance of grounding to personal safety.
3, preventive measures (l), the selection of qualified lamps, especially for the coastal wet weather in the city, must use better anti-rust light pole; lampshade whether it is plastic or glass, should have strong resistance to typhoon .
(2), lawn lights, floor lamps generally pursue the effect of embellishment, in the design and selection should consider the impact of the temperature generated by high-power incandescent. Relevant data show that 40W light bulb surface temperature can reach 563 ° C, 60W can reach 137-180 ° C, 100w can reach 170
- 216 ° C, so in the low and small protective cover, the ground lamp, lawn lamp installed 60W or more bulbs, it is easy to make the protective cover too high temperature and burn people. In addition, some lawn lights have been selected several times in order to select chic, the corners are too sharp, and it is easy to hurt children who like to touch.
(3), grounding is a matter of life, street lights, lawn lights, garden lights and ground lights must have good grounding; the grounding pole of the light pole must be welded firmly, the joint is tin, the PE protection line of the street light power supply and the pole grounding report When connecting, you must use a spring washer to press the top and then screw the nut.
XI. Telephone and TV system wiring and panel wiring do not meet the requirements
1. Phenomenon (1). A number of telephone lines are bundled and fixed in the weak electric shaft of the high-rise building, which is messy.
(2), the wire box number of the DP box is not obvious, the numbered card resurgence, the font is difficult to distinguish.
(3), the telephone socket wiring is loose, and the telephone sound quality is distorted.
(4) The TV antenna damages the shielding layer and the TV audio and video is distorted.
(5), the dirty wall surface during construction, failed to clean the net site after the completion of construction.
2. Reason analysis (1) The responsibility of the construction personnel is not strong.
(2), the arrival time is relatively late, as a professional team, from the availability of the site conditions to prevent the wiring from being stolen, TV and TV teams generally enter the site late, at this time the walls of the civil construction often have completed the painting process, so they It is easy to stain the wall during construction.
3. Preventive measures (1) Strengthen the management of construction personnel and work closely with the civil engineering profession. The construction site should be cleaned to keep the ground and walls clean.
(2) When multiple telephone lines are laid in the weak electric shaft, bundle them into bundles, and ask to fix the trunking cover at the fixed line slot every 1.5 meters.
(3) The telephone line connector should be connected with moisture-proof wiring connector and clamped with wire clamp; the telephone socket should be carefully tightened with screws, and the wire should be tightened and the wiring should not be broken (the telephone core is small).
(4) The telephone lines in the DP box should be neatly arranged. The line heads of each telephone line are marked with a moisture-proof line card to indicate the circuit and the room number, so as to facilitate future telephone installation.
(5) The shielding layer of the TV antenna is easily scratched by the hard object when the tube is worn. Therefore, the tube should be cleaned before threading, and the tube should be smoothed and carefully pulled when threading, so as not to damage the shielding layer and ensure the TV. The image and sound quality are clear.
12. The installation of the probe for fire protection and intelligent systems does not meet the requirements.
1. Phenomenon (1), the probe is loosely installed, and there is a gap between the wall, the board and the ceiling.
(2) The probe and the lamp are too close together, and the heat of the lamp affects the sensitivity of the probe.
2. Reason analysis (1) The construction personnel did not carefully level and fix the probe base.
(2) The installation plane is narrow, and the distance between the probe and the lamp is not leveled when the tube box is pre-embedded.
3. Precautionary measures (1) Reinforce the responsibility of the construction personnel. When installing the base, be sure to level with the pole and wall. Pay attention to tightening when installing the probe.
(2) Under normal circumstances, the smallpox area of ​​the bathroom is small, which tends to make the lamp and the smart probe too close. At this time, the center point of the lamp and the distance of the probe from the window should be properly adjusted to ensure that the distance between the two is about 50CM. .
The fire-fighting probe on the top of the public walkway ceiling should be kept at a distance of not less than 50 CM from the luminaire when the cable box is embedded (the luminaire is guaranteed to be in the center position).