Matters needing attention in water and electricity installation. Those places are easy to forget and miss.

Common faults in electrical engineering

A, lightning protection grounding does not meet the requirements.

1, phenomenon

(l) There are defects such as slag inclusion, flash, virtual welding, bite and incomplete penetration at the joints of down lead, equalizing ring and lightning protection belt.

(2) The welding slag is not knocked out, and the welding place on the lightning protection belt is not brushed with antirust paint.

(3) Use rebar instead of round steel as lap reinforcement.

(4) Directly use butt welding main reinforcement as lightning protection downlead.

2. Cause analysis

(1), the operator's sense of responsibility is not strong, and the welding technology is not skilled. Most of them are versatile hand welders in electrician classes, and their vertical welding skills are poor.

(2) The site construction administrator failed to implement the relevant provisions of the national construction and acceptance standard GB50 169-2006 Code for Construction and Acceptance of Grounding Devices in Electrical Equipment Installation Engineering.

3. Preventive measures

(l) Strengthen welder skills training, and require lap welds to be full, flat and uniform, especially for difficult welding such as vertical welding and overhead welding.

(2) 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.

(3) According to GB50 169-2006 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 engineering 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.

Second, the pretreatment of outdoor inlet pipeline does not meet the requirements.

L, phenomenon

(1), replace thick-walled steel pipe with thin-walled steel pipe.

(2) The buried depth is not enough and the position deviation is large.

(3) Arc welding and bending, and the upper wall pipe is connected with the horizontal household pipe network by 90 electric welding.

(4) The entrance pipeline and basement exterior wall are not well waterproof.

2. Cause analysis

(l) 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 with the control or dare not raise objections to the contractor's intentional violation of regulations, and does not resolutely implement the norms and standards; There are loopholes in supervision's management of materials entering the site.

(2) insufficient coordination with civil engineering and other professional teams.

(3), there is no pipe bender or can't use a pipe bender, the sense of responsibility is not strong, and it is convenient to use electric welding to burn.

(4) Workers who pre-buried household pipes don't understand waterproof technology and don't ask waterproof professionals for help.

3. Preventive measures

(l) The embedded pipes must be thick-walled copper pipes or PVC pipes that meet the requirements (generally, the wall thickness of PVC φ L 14 is above, and φ 56 is meters).

(2) Strengthen the coordination with civil engineering and other related majors, define the outdoor floor elevation, and ensure that the buried depth of the embedded pipeline is not less than.

(3) Strengthen the education of relevant laws and regulations for the contractor team leader and material buyer, and the supervisors should strictly implement the requirements of mandatory inspection for materials entering the site to plug the loopholes.

(4) The elbow on the embedded steel pipe wall 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.

(5), completes the waterproof processing, please waterproof professionals on-site guidance or waterproof processing by waterproof professional team.

Three, wire tube (steel pipe, PVC pipe) laying does not meet the requirements.

1, phenomenon

(1), the cable pipes are overlapped in multiple layers, and there is gluten higher than steel bars in this temple.

(2) Connect two or more wires and pipes side by side.

(3) The depth of the conduit buried in the wall is too shallow, even buried in the silty layer outside the wall. The pipe is bent, painfully folded and sunken.

(4) When the conduit enters the distribution box, the nozzle is not filled in the box.

Exposure time is too long; The nozzles are uneven and have different lengths; Nozzle without guard ring; Not locked and fixed.

(5) When embedding PVC conduit, instead of plugging the conduit with a plug, clamp the elbow with pliers.

2. Cause analysis

(1), the construction personnel are not familiar with the relevant specifications, their working attitude is sloppy, they are greedy for convenience, and they do not operate according to regulations. The management of the construction manager is not in place.

(2) Insufficient coordination between architectural design and layout and electrical specialty leads to multiple conduits passing through the same narrow plane.

3. Preventive measures

(1), strengthen the quality control of on-site construction personnel in the construction process, and conduct targeted training for workers; Managers should be familiar with relevant norms and strictly manage.

(2) Multi-layer overlapping of electric wires and conduits generally occurs in public passages of high-rise buildings. When there are more than 6 sets of tower houses on each floor, it is suggested that the civil works should decorate the ceiling of the corridor closely, so that most of the household lines of electrical specialty can directly enter the home through the trunking laid above the ceiling. You can also hide many electric conduits by thickening the floor of public walkways. When laying pipelines, the construction personnel of electrical specialty should try to reduce the overlapping layers of conduits at the same point.

(3), wire layer can't close side by side, such as construction is difficult to separate, can use small cement block to separate it.

(4), wire tube buried in the brick wall, the distance from its surface should not be small, pipeline laying to "horizontal flat vertical".

(5) The bending radius (buried) of electrical conduit shall not be less than 10 times of the outer diameter of the pipe. When bending a pipe, you should use a pipe bender or a pipe bender to make the pipe bender straight and smooth, and there will be no flat folds and dents.

(6), wire tube into the distribution box to level off, the length of 3, nozzle with sheath and lock the box shell. The nozzle of the conduit entering the floor-standing distribution box should be 50 higher than the basic surface of the distribution box.

(7), embedded PVC wire tube, it is forbidden to use pliers to clamp the nozzle flat, bending, the application of PVC plug cap in line with the diameter of the nozzle, and tape binding firmly.

Four, wire connection, connection quality and color code does not meet the requirements.

1, phenomenon

(l) Multi-strand conductors are made into a "sheep's eye" shape without copper joints, but Wuxi expands.

(2) When connected with the terminals of switches, sockets and distribution boxes, one terminal is connected with several wires.

(3), the thread is bare, the wires are not arranged neatly, and there is no binding.

(4) The color codes of three-phase conductor, zero line (N line) and grounding protection line (PE line) are inconsistent or confused.

2. Cause analysis

(l) Construction personnel are not familiar with wiring technology and wire technology.

(2) The material buyer fails to prepare enough colors and quantities of various wires required for construction as required, or the construction management personnel mix them to save materials.

3. Preventive measures

(l) Strengthen the training of construction personnel in learning norms and skills.

(2), multi-strand wire connection, the application of galvanized copper joint pressure welding, try not to do "sheep's eye" shape, if so, it should be evenly tinned.

(3) Only 1 wires should be connected to the posts and terminals. If two wires need to be connected, a flat pad should be added in the middle; No more than 3 connections are allowed.

(4) The wire arrangement should be horizontal and vertical, and the length of each wire head should be consistent when stripping the wire head, and there should be no bare core after the wire is inserted into the terminal; The joint of copper connector and conductor should be wrapped with insulating tape with the same color as conductor.

(5), material procurement personnel must be equipped with wires of various colors according to the needs of the site.

(6) Construction personnel shall clearly distinguish the roles of phase line, zero line (N line) and grounding protection line (PE line) from the color code, that is, PA phase-yellow, B phase-green and C phase-red; Generally, red should be used for single phase; The zero line (N line) should be light blue or blue; Grounding protection wire (PC level) must use yellow-green double-color conductor.

Five, distribution box installation, wiring does 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 sundries in the box are not cleaned.

(3) The opening of the box shell does not meet the requirements, especially electric welding or gas welding, which seriously damages the paint protective layer of the box and damages the beauty of the box.

(4) The grounding of the grounding power box is not obvious (it is not easy to find under the box bottom), and the cross section of the repeated grounding conductor is not enough. The wire head in the box is exposed, the wiring is irregular, and there is no wire allowance.

2. Cause analysis

(l) When installing the box, the cooperation with the civil works is not enough, and the civil works are not full, so it is useless to level the box during installation.

(2) Carefully clean the mortar sundries in the box.

(3) When the "knock-out hole" opening of the box body does not match the air inlet pipe, it must be mechanically opened or sent back to the factory for re-processing, or strictly calibrated when ordering, and produced according to the size.

(4), strengthen inspection and supervision, enhance the sense of responsibility of construction personnel.

(5) Thoroughly understand the relevant regulations of the acceptance department on grounding. According to the requirements of the power supply department and the municipal quality inspection station, the grounding and wires of the power box must be exposed, and welding or wiring cannot be carried out under the box bottom. According to the specification, when the phase line section S of the device is less than or equal to 2, the minimum section of the grounding wire is S; 16 < s ≤ 2, the minimum section of grounding wire is 2; When s > 2, the minimum cross section of grounding wire is s/2.

(6) The threading in the box should be unified, not bare, the wiring should be neat and beautiful, and the wires should be tied and fixed with a certain margin, generally 10 in the box.

Six, switch, socket box and panel installation, wiring does not meet the requirements.

1, phenomenon

(1), the box is embedded too deeply, and the elevation is different; There is a gap between the panel and the wall, and the panel is polluted by glue paint and is not straight.

(2) There are mortar sundries in the box.

(3) The phase line, zero line and PE protection line of the switch and socket are connected in series.

(4) The wire ends of switches and sockets are exposed, the fixing bolts are loose, and the wire allowance in the box is insufficient.

2. Cause analysis

(1), the embedded box is not fixed firmly, the template expands, and the coordinates are not allowed during installation.

(2), the construction personnel's sense of responsibility is not strong, lack of understanding of the importance of electricity safety, covet convenience.

(3) There is an unreasonable concept of saving materials.

3. Preventive measures

(1), work closely with the civil engineering specialty to fix the box accurately and firmly; When the embedded box is too deep, a box should be added. When installing the panel, it should be horizontal and vertical, and the level should be adjusted with a spirit level to ensure the uniformity of the installation height. In addition, the panel should be fully patched after installation, and there is no gap, so the panel should be cleaned and protected.

(2) Strengthen management and supervision to ensure that the phase line, zero line and PE protection line in the switch and socket cannot be connected in series, and clean the mortar in the box first.

(3) When stripping wires, the size should be fixed to ensure that the thread ends are neat and consistent, and the thread ends are not exposed after installation; At the same time, in order to firmly press the wire, the single-core wire should be twisted into two strands when inserted into the wire hole, and tightened with screws.

(4) The wires in the switch and socket box should have a certain margin, generally100; We must resolutely stop unreasonable material saving and greed.

Seven, lamps and lanterns, ceiling fan installation does not meet the requirements.

1, phenomenon

(l) The lamp position is installed off center.

(2) The levelness and straightness of lamps in rows have great deviation.

(3) The fluorescent lamp chain of the suspension chain is not parallel, and the led line is not braided.

(4) The ceiling fan hook is processed with rebar, and the molding is poor; The bell jar does not absorb the top and the junction box is exposed.

(5) The iron plate on the balcony lamp chassis falls off and rusts.

(6) The simple lamp on the ceiling has a large and irregular opening.

2. Cause analysis

(l) When the light box was embedded, the position was wrong and deviated, and no remedial measures were taken when installing lamps.

(2), the builder's sense of responsibility is not strong, not familiar with the current construction and acceptance specifications, quality inspection and evaluation standards.

(3) When buying lamps, buyers are greedy for publicity, regardless of quality;

(4) When the downlight is turned on, there is no fixed size and ethnic position, and the diameter of the round hole is not uniform.

3. Preventive measures

(l) Before the installation of lamps and lanterns, carefully determine the center point and correct the deviation in time.

(2) According to the specifications, the installation deviation of rows of lamps should not be greater than that. Therefore, it is necessary to stay in the construction to make the lamps in the vertical, horizontal, oblique, main pipes and low water evenly in a straight line.

(3) The hanging chains of fluorescent lamps shall be straight with each other, and there shall be no splay. The electric wire should be woven with the lifting chain.

(4) When the ceiling fan hook is embedded, galvanized round steel not less than Ф 8 shall be fixed with the steel bar in the plate, and rebar shall not be used. Hooks should be shaped in the same way and coated with antirust paint. The bell jar of the ceiling fan can absorb the ceiling and cover the hook and junction box. Rows of ceiling fans should be in a straight line with a deviation ≤.

(5) The thickness of the iron plate in the balcony lamp box is ≥, and the paint surface is even and smooth, which can play a good role in rust prevention; The glass cover should not be too thin to avoid cracking during installation.

(6) The coordinates of the downlight opening on the ceiling should be determined first. The size of the opening should not only be straight, neat and uniform, but also conform to the specifications of the downlight, and should not be too large, so as to ensure that the outer ring is firmly attached to the ceiling when the downlight is installed, and no cracks are exposed.

(7), construction personnel, procurement personnel should conscientiously implement the relevant national and local norms.

Eight, cable, bus installation does not meet the requirements.

L, phenomenon

(l) After installation, cables are not uniformly listed, and cables are laid in cable trench and bridge due to civil strife.

(2) In the shaft, the cable hole is not blocked tightly; The bracket for vertically fixing the cable is too small and soft, and inclines downward.

(3) After the cable passes through the inlet pipe, the sealing is not strict.

(4) The terminal (lug) is too large or too small, and the wall is too thin, so it will break when crimping.

(5) The busbar box is not installed straight, and each busbar is too long to be transported and installed easily.

2. Cause analysis

(1), the cable construction unit does not cooperate well, and only the cable laid by itself can pass.

(2) When plugging the high-pressure shaft, there was no coordination with the civil engineering unit, and the construction personnel did not master the plugging technology.

(3) If the materials are unqualified, the buyer fails to purchase cable fixing brackets and terminals according to the standards.

(4) The area of the reinforced electric shaft reserved by the architectural specialty for the electrical specialty is too small, which makes it difficult to arrange the electric shaft.

3. Preventive measures

(1), the cable construction team should coordinate well, arrange the direction and position of large and small cables respectively, and list them with damp-proof and anti-corrosion cards after installation, indicating the line numbers, models, specifications and starting and ending points of various cables. The listed positions are: cable terminal head, turning philosophy, interlayer, shaft ends, artificial process holes in cable trench, etc.

(2) Use hemp and asphalt mixture to block the hole through which the vertical shaft cable passes. When there is outdoor entrance in the basement, the nozzle should be waterproof, which needs to be closely coordinated with civil engineering. Clean up the site after sealing.

(3) When purchasing materials such as cable round brackets and terminals (lugs), they should be purchased according to the specifications. When crimping the joint, accurately select the corresponding hydraulic tongs and supporting tools.

(4) When ordering buses, it must be ensured that each bus is not greater than the height of each floor; Generally not more than, in order to facilitate the handling and installation in the building.

(5) When buses and accessories come into the site, they shall be inspected in strict accordance with GBJ 149-90 Code for Construction and Acceptance of Bus Devices in Electrical Equipment Installation Engineering and the provisions of the contract.

(6) When installing the plug-in box, it should be horizontal and vertical, and the contact with the bus bar is reliable and firm.

Nine, indoor and outdoor cable trench structures and cable pipe laying does not meet the requirements.

L, phenomenon

(1), cable trench and concrete support are not straight and easy to break.

(2) The drainage of cable trench and cable pipe is not smooth.

(3) The buried depth of the cable crossing pipe is not enough, and the bell mouth is damaged irregularly.

(4) The rust-proof duty paint of steel pipe is uneven, and the sealing performance is not enough, especially the rust-proof and corrosion-proof inside the pipe is not done well.

(5) The grounding electrode is not straight and loose in the cable trench, and the grid connection with the pipe is not comprehensive, and some pipes are missing welding.

2. Cause analysis

(1), the civil construction unit is not serious in construction; The bearing capacity of precast concrete support is not enough because of aging or lack of reinforcement as bone.

(2) There is no certain slope at the bottom of the cable trench, and there is no sump according to the specification; The objective conditions on site do not meet the drainage requirements.

(3) The sense of responsibility of installation and construction personnel is not strong, and there are other professional pipes or wells that affect the laying of cable pipes.

(4) When arranging the camps one by one as required, the ends of the earth were not welded one by one. When all pipes are buried before welding, the conditions are no longer allowed to weld one by one, so we have to weld at the bell mouth to make up the number.

3. Preventive measures

(l) When installing the concrete support, the civil engineering unit should stay for leveling and alignment; Among them, the distance from the top bracket to the top of the ditch is-,and the distance from the bottom bracket to the bottom of the ditch is-. Qualified concrete supports should be purchased from qualified manufacturers to ensure sufficient supporting force; Steel supports should be well protected against rust and corrosion.

(2) According to GB 50054-95 Code for Design of Low-voltage Power Distribution, the slope of the drainage ditch at the bottom of the cable trench should not be less than 0.5%, and a sump should be set to drain the accumulated water directly into the sewer; The sump practices refer to the relevant building codes, and also refer to the Atlas of Building Electrical Installation Engineering edited by Lv Guang, the second edition, Volume 1, Volume 5? General practice of 35 "cable manhole? quot。 When the sump is far away from the rainwater well or the elevation of the rainwater well is higher than the bottom of the cable trench, the corresponding drainage system should be adjusted accordingly. Therefore, in the joint inspection of outdoor comprehensive pipe network diagram, the elevation of each specialty should be carefully compared.

(3) The bell mouth should be uniform without cracks. When the cable pipe is embedded, the depth should be as follows: If the objective conditions cannot be met, the pipeline should be encapsulated with cement mortar to ensure that the pipeline is not crushed.

(4) The cable pipe is made of thick-walled copper pipe, and the inside and outside are painted with anticorrosive and antirust paint or asphalt, and the paint surface is even; Especially in welded joints, rust prevention treatment is needed. When two cable pipes are butted, the inner nozzle should be aligned, and then a short sleeve (the length is not less than 2.2 times of the outer diameter of the cable pipe) should be added for firm sealing welding.

(5) The grounding shoulder steel in the cable trench shall be firmly installed, and generally a fixed terminal shall be installed every 0.5-, and the height of the high trench bottom shall be-. When crossing the crossing pipe, it should be overlapped with each steel pipe respectively, and the overlapping place should be treated with anti-corrosion and anti-rust. In order to ensure that each steel pipe can be reliably overlapped with the grounding electrode, it should be welded one by one when buried, and it is not allowed to be welded after buried.

X the installation of street lamps, lawn lamps, courtyard lamps and floor lamps does not meet the requirements.

1, phenomenon

(1), the lamp pole is painted, rusty and loose.

(2), grounding installation does not meet the requirements, even without grounding wire.

(3) The lampshade is too thin and easy to be damaged and fall off.

(4) The bulb wattage of lawn lamp and floor lamp is too large, and the temperature of lampshade is too high when using, which is easy to burn people; Or the lampshade is sharp, which is easy to cut people.

2. Cause analysis

(1), there is no strict requirement for buying lamps; Rust-proof layer is not done well; The glass or plastic strength of the lampshade is not enough; The bolts fixing the lamp holder are inconsistent and difficult to fix.

(2) Only lighting is considered in the design, which may cause harm to pedestrians, especially children.

(3), the construction personnel do not seriously implement the specification, and have insufficient understanding of the importance of grounding to personal safety.

3. Preventive measures

(l), choose qualified lamps and lanterns, especially for the wet weather in the coastal areas of our city, we must choose a lamp post with good rust resistance; The lampshade, whether plastic or glass, must have strong typhoon resistance.

(2) Lawn lamps and floor lamps generally pursue ornament effect, and the temperature influence caused by high-power incandescent lamps should be considered in design and selection. Relevant data show that the surface temperature of 40W bulb can reach, and that of 60W bulb can reach 137- and 170-, 100 W can reach 170-. Therefore, it is very easy to burn people by installing more than 60W bulbs on low-floor lamps and lawn lamps with narrow protective covers. In addition, some lawn lights are too sharp, which are not suitable for unique choices and are easy to hurt children who like to touch. This kind of accident happened several times in Yitian village.

(3) Grounding is a matter of life. Street lamps, lawn lamps, garden lamps and floor lamps should be well grounded; The grounding pole of the lamp pole must be welded firmly and the joint must be tinned. When the PE protection line of street lamp power supply is connected to the grounding report of lamp pole, it must be pressed with spring washer and then screwed with nut.

Eleven, telephone, television system wiring, panel wiring does not meet the requirements.

1, phenomenon

(1), several telephone lines are tied and fixed in the weak current shaft of high-rise building, which is messy.

(2) The number of lines in the 2)D P box is not obvious, and the numbered cards are popular again, so the fonts are difficult to distinguish.

(3) The telephone socket wiring is loose and the telephone sound quality is distorted.

(4) The shielding layer of the TV antenna is damaged and the TV audio and video are distorted.

(5) The wall was dirty during the construction, and the site was not cleaned after the construction.

2. Cause analysis

(1), the construction personnel have a weak sense of responsibility.

(2) TV and TV teams, as professional teams, generally enter the site late to prevent the wiring from being stolen. At this time, the wall of civil works has often completed the painting process, so it is easy for them to dirty the wall during construction.

3. Preventive measures

(1), strengthen the management of construction personnel, cooperate closely with civil engineering specialty, clean up the site after construction and installation, and keep the ground and wall clean.

(2) When laying multiple telephone lines in the weak current shaft, they should be laid in bundles, and every other slot should be fixed and the slot cover should be covered.

(3) The telephone line connector should be connected with the moisture-proof wiring connector, and pressed with the clamp; When wiring the telephone base, be careful to tighten the screws, so that the wires can be tightened without breaking (the telephone line core is small).

(4) The telephone lines in the 4)DP box should be arranged neatly, and the thread head of each telephone line should be marked with a moisture-proof line card, indicating the loop and room number, so as to install the telephone in the future.

(5) TV antenna shielding layer is easy to be scratched by hard objects when threading. Therefore, the pipe should be cleaned before threading, and the pipe should be smooth. Be careful when threading, so as not to damage the shielding layer and ensure the clarity and sound quality of TV images.

Twelve, fire protection, intelligent system probe installation does not meet the requirements.

1, phenomenon

(1), the probe is loosely installed and has a gap with the wall, plate and ceiling.

(2) The probe is too close to the lamp, and the heat of the lamp affects the sensitivity of the probe.

2. Cause 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 uneven when the pipe box is embedded.

3. Preventive measures

(1), to enhance the sense of responsibility of the construction personnel. When installing, the base must be flush with the pole and wall, and pay attention to tighten the probe when installing.

(2) Under normal circumstances, the ceiling area of the bathroom is small, which often makes the lamps too close to the intelligent probe. At this time, the distance between the center point of the lamp and the probe and window should be properly adjusted to ensure that the distance between them is left and right. The fire detector on the ceiling of the public walkway should keep a considerable distance from the lamps when embedding the box (the lamps should be in the central position).