1. Electrical wiring:
1. Material preparation before construction
Insulated wire specifications and models must meet the design requirements and have a factory certificate of conformity.
The pipe guard is selected, and the general plastic parts are flame retardant.
Select the terminal with the specifications corresponding to the number of wires and the total cross section.
Process flow: select the wire → sweep the pipe → wear the wire → put and break the wire → the wire and the band gauze protection of the wire → wire connection → wire welding → wire wrapping → line inspection insulation shake test.
2. Wire laying:
a. All conduits or ducts are made of flame-resistant PVC plastic ducts or galvanized ducts.
b. Before the pipe is threaded, the water and debris in the pipe should be removed, and the burr on the pipe mouth should be smooth and smooth.
c. The total cross-sectional area of the inner conductor of the pipe (including the outer sheath) does not exceed 40% of the cross-sectional area of the pipe, refer to the following table:
a. The fixed distance of the trunking: the bottom plate is not more than 500mm, the cover is not more than 300mm, the bottom plate is 50mm from the terminal and the cover is 30mm from the terminal. The bottom and cover interfaces should be staggered 20mm when laying the trunking.
b. When the wire trunk is connected to the base of the appliance, the base should press the head of the wire trunk, and the wire should have a margin.
c. The wires should not have joints or kinks in the tube or trunking. If they must be connected, they should be connected in the junction box.
d. There must be no wrinkles, dents, cracks, etc. in the bend of the electric wire tube. The degree of flattening must not be greater than 10%. The bend radius of the wire tube is not less than 6D when exposed and not less than 10D when exposed.
e. Wires and pipelines are connected every 45 meters when there is no bend, every 30 meters when there is a bend, every 20 meters when there is a bend, and every 12 meters when there are three bends. A junction box should be added.
f. The wires in the vertical pipe shall be fixed in the nozzle or junction box at the following lengths: those with a cross-section of less than 50mm every 30 meters, those with a cross-section of 70-95 mm2 every 20 meters, and those with a cross-section of 120-240 mm2 every 18 meters.
g. Lines with different systems, different voltage levels, and different current categories should not be routed in the same pipe or in the same slot in a trunking.
h. When laying the wire in the trough, it should be fixed at a specified distance and marked with a number.
i. Terminals with more than 2.5 mm² stranded copper core wire should be soldered or crimped to the terminal before connecting with the terminal of the electrical equipment.
j. The ground wire should be yellow and green two-color insulated multiple-strand copper core wire as the ground wire.
k. Conduct wire color separation construction, L1 phase is yellow, L2 phase is green, L3 phase is red, N line is light blue, and PE protection line is yellow and green. Use the line strictly according to the specified color, so that the color of the phase line, zero line and ground line of the entire project is always consistent.
1.Circuit inspection and insulation shake test
a. Circuit inspection: After all connection, welding and wrapping are completed, self-inspection and mutual inspection should be performed to check whether the wire connection, welding and wrapping meet the design requirements and relevant construction acceptance specifications and quality and evaluation standards. It should be corrected immediately, and the shake test should be performed after the check is correct.
b. Insulation shake test: Insulation shake test for lighting circuits generally uses a 500V megohm meter with a range of 0-500MΩ. The insulation resistance value of the lighting circuit is not less than 0.5MΩ, and the insulation resistance value of the power line is not less than 1MΩ.
2. Quality issues that should be paid attention to during construction
a. During the construction, there are missing, falling, damaged and inconsistent pipe diameters, etc. Those who have missed or fallen out of the protective hole due to careless operation shall be promptly replaced, and those with damaged or inconsistent pipe diameters shall be replaced in time.
b. When the copper wires are connected, the number of windings of the wires is less than 5 turns. The connectors that are not connected according to the process requirements should be removed and reconnected, tightly wound and compressed to ensure reliable contact.
c. The solder at the connection of the wire is not full, and there are phenomena such as false soldering and slag inclusion. The temperature of the solder must be appropriate and the tin must be uniform. After soldering, apply a cloth strip and wipe away excess flux to keep the joints clean.
d. The damaged wire core is caused by excessive force and improper use of the wire stripper. When stripping the wire, the corresponding blade of the wire stripper should be selected according to the wire diameter.
e. Missing soldering of multiple strands of soft copper wire should be repaired in time.
f. The bandage of the joint is uneven and tight, and it should be rebanded according to the process requirements.
g. The screw terminal is loose and the core is exposed. Unqualified wiring buttons and short cuts of the cores will cause the loose branches to be cut too long, which will cause the cores to be exposed. Qualified products corresponding to the cross section and the number of conductors should be selected. The recommended length is 1.2m.
h. After the sleeve is crimped, the position of the stamper is not on the center line, the mold is not matched and the depth is not sufficient, and a qualified stamper should be used for crimping.
i. The insulation resistance of the line is low. Water in the pipeline or damage to the insulation layer will cause the insulation resistance value of the line to be low. The muddy water in the pipeline should be cleaned in time or the wires should be replaced.
j. A single-stranded copper core wire with a cross section of 10mm² or less, a multi-stranded copper core wire with a cross-section of 2.5mm² or less can be directly connected to the terminal of an electrical appliance, but the multi-strand copper core should be tightened first, and then tinned before connecting .
Installation of cable trays and trunking:
a. The distance between the horizontal strong electric cable bridge and the bracket should not be greater than 2m. The hanger and bracket are used for the installation. For specific installation, refer to the installation standard provided by the national standard 86SD169 and the bridge manufacturer. The overall plane layout of cable trays and cable trunking should be the shortest distance, economic and reasonable, safe operation, and should meet the requirements for installation, laying of cables and maintenance.
b. After the cables and wires are laid, the deflection of the cable tray and the trough should not be greater than 1/200 of its span. When the span is ≥6000mm, its deflection should not be greater than 1/150 of its span.
c. For cable bridge installation, support and hanger should be selected according to local conditions. The support and hanger of the bridge should be consistent within a certain section.
d. Electric and gas welding is strictly forbidden for cable bridge connection.
e. When installing the cable bridge and wire trough with the process pipe rack, the cable bridge and wire trough should be arranged on one side of the pipe rack.
f. When the cable bridge is erected in parallel and crosswise with various pipes, the net distance shall meet the specified requirements.
g. When the cable tray and cable trough pass through the wall from the normal environment to the fireproof and explosion-proof environment, corresponding sealing devices shall be installed on the wall.
When cable trays and cable troughs cross walls from indoor to outdoor, lightning protection measures should be taken on the outside of the wall.
When passing through the expansion settlement joint, the cable bridge should be disconnected, and the disconnection distance should be about 100mm.
Expansion joints should be used when the trunking passes through the expansion settlement joint. When two sets of cable trays and cable trays are installed on the same channel beam, the clear distance between the two sets of cable trays and cable trays is not less than 50mm.
h. When multi-layer installation of cable trays and troughs for laying cables of 10KV and below, the distance between layers is generally not less than 50mm. ( Refer to clean room
i. The distance between the cable tray and the bottom of the floor, beam or other obstacles should not be less than 300mm.
j. When the cable tray and cable trough are installed horizontally, their connecting plates should not be placed on a span of ² or on a support point.
k. The cantilever section appearing during the installation of cable trays and trunkings should generally not exceed 100mm.
l. Cable trays and trunkings should not be used as pedestrian walkways.
Third, the distribution box (panel) installation
1. Preparation of materials
a. Iron distribution box (panel): The box body should have a certain mechanical strength, the surroundings should be flat without damage, and the paint should not fall off. The thickness of the second floor is not less than 1.5mm. Various appliances in the box should be installed firmly and the wires arranged neatly. The crimp connection is firm, and the product has a certificate of conformity. The equipment has a nameplate, which meets the design requirements. The technical documents, accessories and spare parts are complete.
b. Other auxiliary materials and tools.
2. Distribution box (panel) installation
The construction and installation of the low-voltage electrical equipment of this project shall be carried out in accordance with GB50254-96 "Code for Construction and Acceptance of Low-Voltage Electrical of Electrical Installation Engineering".
a. Before the installation of the device, it must have embedded parts and reserved holes that meet the design requirements. The embedded parts are firm, the base channel is straight, and it is installed upright or wall-mounted according to different structures. The terminal signs are clear, the connection is good, and the ground is reliable.
b. The internal components of the power distribution equipment are neatly arranged for easy operation and maintenance. The measured insulation resistance complies with the regulations. The neutral and PE wiring terminals and bus bars should be arranged separately. The neutral terminals should be installed on the insulator.
c. The distribution box (panel) installation should be firm and flat, and the allowable deviation of verticality is 3mm.
d. Fixing of distribution box (panel): The surface installation of this project is fixed with expansion bolts. The concealed box (panel) should be marked according to the size of the reserved hole, and the surrounding diagrams should be filled with cement mortar. , The periphery is uniform, the symmetrical face (door) is flat and not skewed.
3.Insulation resistance shake test
After the installation of all electrical appliances in the distribution box (panel), use a 500VMΩ meter to perform an insulation shake test on the line. The shake test items include phase to phase, phase to neutral, and phase to ground. The two people carried out shake tests, and at the same time made records and archived technical data.
Fourth, switch, socket installation
1. Material preparation
The specifications and models of the selected switches and sockets must meet the design requirements and have a product certification.
2. Process flow: cleaning → wiring → installation
a. Clean up. Use a ladle to gently remove the residual ash in the box, and at the same time remove other debris out of the box, and then wipe the dust inside the box with a damp cloth, the surface is clean and not deformed, and the cover plate is close to the building. surface.
b. Wiring. Switch wiring: The switch cut-off position is the same in the same place, and the operation is flexible, the contact is reliable, and the phase of the electrical lamp should be controlled by the switch.
Socket wiring: single-phase two-hole sockets are available in horizontal and vertical installations. When horizontally installed, the right poles of the two pairs of sockets are connected to the phase line, and the left poles are connected to the neutral line; The pole is connected to the neutral line, and the single-phase and two-hole grounding should be at the top, and the left, zero, and right fire.
Connect the wires from the box to the panel of the switch and socket. Push the switch and socket into the box (if the box is deeper than 2.5cm, install a box). Align the eye of the box and fasten with the screws. Firmly, make sure the panel is straight and flush with the wall when fixing.
When installing switches and sockets, do not damage the wall, and keep the wall clean.
After the switch and socket are installed, do not spray again to keep the panel clean.
Do not damage or distort switches and sockets during construction of other types of work.
4. Quality issues that should be paid attention to during construction
a. The switch has not disconnected the phase line, and the phase, neutral and ground of the socket are crimped, and should be corrected as required.
b. The difference in the installation height of the switches and sockets in the same room exceeds the allowable deviation range and should be corrected in time.
V. Lighting Installation Engineering
1. Material requirements:
Various types of lamps: The models and specifications of the lamps must meet the design requirements and national standards. The wiring inside the lamp is strictly forbidden to be exposed, the lighting fixtures are complete, there is no mechanical damage, deformation, peeling paint, lampshade distortion and other phenomena.
All luminaires shall have product certification.
Lamp wires: The voltage of the wires used in lighting lamps shall not be lower than 500 VAC, and the minimum core cross section shall meet the requirements of the following table:
Plastic table: The plastic table should have sufficient strength, and there should be no warpage and deformation after being stressed; the wooden table should be complete without splitting. The paint is intact and does not come off.
Hanging pipe: When the steel pipe is used as the hanging pipe of the lamp, the inner diameter of the steel pipe is generally not less than 10MM.
Hook: The diameter of the round steel hook of the lantern is not less than the diameter of the hanging pin, and not less than 6MM.
Porcelain joint: It should be intact and all accessories are complete.
Bracket: Galvanized material of corresponding specifications must be selected to make the bracket according to the weight of the lamp.
Light fixtures: Plastic fixtures must be free of cracks and defects.
Other materials: Expansion tube, wood screws, bolts, nuts, washers, springs, iron parts for lamp holders, lead wires, lamp sockets, bulbs, fuses, hanging boxes, soft plastic tubes, freezer, hanging chains, wire clips, lampshades, Nylon wire mesh, solder, flux, rubber insulation tape, black tape, abrasive cloth, asbestos cloth, etc.
1. Quality standards:
Guaranteed items: The metal shell part of the lamps below 2.4mm should be connected or connected to zero protection.
(1) Installation of lamps and lanterns: The lamps and lanterns are installed firmly and correctly, and the position is correct. The lamps and lanterns are installed in the center of the wooden table. The appliances are clean and clean, and the boom is vertical, fixed and reliable, and arranged neatly.
(2) The connection between the lead and the lamp: the insulation of the lead entering the lamp is good, with a proper margin. The connection is firm and tight without hurting the core. When the pressure plate is connected, there is no looseness when tightening, and when the bolt is connected, no more than two wires are on the same terminal. The down-conductor is neat and beautiful.
Allowable deviation items: The center line of the appliances installed in a row allows a deviation of 5mm.
Inspection method: wiring and ruler inspection.
2. Quality issues to be noted:
The deviation of the center line of the row of lamps is beyond the allowable range. When determining the position of a row of luminaires, a line must be drawn, preferably a crosshair.
The wooden table is not fixed firmly, and there is a gap with the building surface. When the diameter of the wooden table is 150mm or less, it should be fixed by two screws; when the diameter of the wooden table is more than 150mm, it should be fixed by triangles with three screws.
The flange, hanging box and flat light port are not on the center of the plastic table. The base deviation exceeds 1.5m. When installing, first align the center of the flange, hanging box and flat light port with the center of the plastic table.
When the wooden structure is used for bright (dark) installation of the lamp, the wire joints and ordinary plastic wires are exposed, fire protection measures should be taken, the wire joints should be placed in the lamp holder box, and the plastic wires should be laid with sheathed wires, or placed in flame-retardant Wiring in plastic trunking.