The opening of the conduit should not be open vertically, and the opening of the conduit should be set in the box, box or the end of the conduit should be equipped with a waterproof bend.
4.
6.
(4) Supervision and inspection during construction and re inspection after completion.
The protective bonding conductor fixed with a special grounding card shall be a copper core flexible conductor with a cross-sectional area of not less than 4mm2; The protective connecting conductor welded by fusion welding should be round steel, with a diameter of no less than 6mm, and its lap length should be 6 times the diameter of round steel.
(3) Make a detailed disclosure to the construction team, and hand over the three-dimensional drawings and dimensional data of pipeline layout and component positioning to the construction team.
4.
➤ examples of electrical bridge installation: the bridge crosses the wall and floor, and the fireproof sealing is tight.
When the contact resistance value of the connection meets the relevant requirements of the current national standard conduit system for electrical installation Part 1: General requirements gb/t20041.1, the connection can not be set with a protective bonding conductor, but the conduit should not be used as the connecting conductor of the protective conductor.
There should be rain proof measures for electrical bridges, and there should be drainage holes at the bottom.
➤ common problems in the installation of electrical bridges are set in the open air.
➤ installation example of expansion joint of electrical bridge through deformation joint: use connecting plate to fix the expansion joint of electrical bridge firmly, the grounding jumper connection is perfect, and the supports and hangers are symmetrically installed on both sides of the expansion joint for fixation.
Preventive measures: (1) carefully review the drawings before installation, and try to solve the problems during the joint review of drawings.
3.
➤ the comparison between correct and wrong installation of the connection part of the electrical bridge through the wall is correct: the connection part of the bridge should be set outside the wall for installation and maintenance.
5.
2.
The two ends of the connecting plate between the non galvanized ladder, tray and slot box body shall be bridged with the protective bonding conductor, and the cross-sectional area of the protective bonding conductor shall meet the design requirements.
12.2.6 exposed electrical conduits shall meet the following requirements: 1.
The two ends of the connecting plate between the galvanized tank box bodies are not connected with the grounding wire, but the two ends of the connecting plate are not less than 2 connecting and fixing bolts with anti loose nuts or anti loose washers.
(2) The construction unit did not plan in advance and did not apply BIM Technology to make an overall plan for installation.
When the total length of the ladder, tray and slot box is not more than 30m, there shall be no less than 2 reliable connections with the protective conductor; When the total length is more than 30m, a connection point should be added every 20m~30m, and the starting end and the ending end should be reliably grounded.
3.
Conduits shall be arranged neatly, fixed points shall be evenly spaced, and installed firmly..
(3) The water and electricity installation professional teams are in formation, which is caused by mutual ventilation and coordination.
The metal conduit for mechanical connection, the connecting accessories of pipe to pipe, pipe to box (box) body should be selected as supporting parts, and its connection should meet the requirements of the product technical documents.
➤ installation example of galvanized ladder and slot box, the transition of Z-shaped ladder is natural and smooth, and the support at the turn is in place.
The conductive part of the shell is well connected with the grounding bus.
11.1.1 the connection between the metal ladder, tray or slot box body shall be firm and reliable, and the connection with the protective conductor shall comply with the following provisions: 1.
The conduit leading from box type substation or floor type distribution box to the building, and the conduit orifice on one side of the building should be set in the building.
Error: half of the connecting parts are set in the wall, which is inconvenient for installation and maintenance, and the grounding jumper cannot be connected.
12.2.5 outdoor conduit laying shall comply with the following provisions: 1.
2.
When the non galvanized steel conduit adopts threaded connection, the two ends of the connection shall be welded to protect the connecting conductor.
2.
➤ analysis of the installation distance between the electrical bridge and the sprinkler head and the analysis of preventive measures: (1) the water and electricity majors of the design unit did not coordinate with each other, taking care of themselves, resulting in incorrect positioning.
When the metal conduit is connected with the metal ladder and tray, the connecting end of galvanized material should be fixed with a special grounding card to protect the connecting conductor, and the connection of non galvanized material should be welded to protect the connecting conductor.
It is suggested that engineering friends exchange and learn and deeply understand, so that our electrical installation engineering can meet the requirements of the code.
Based on the current code gb50303-2015 code for acceptance of construction quality of building electrical engineering, this paper summarizes the key provisions of ① bridge, ② conduit, ③ cable and ④ bus installation and construction, supplemented by examples to analyze the quality control of key processes.
Galvanized steel conduit, flexible metal conduit and metal flexible conduit shall not be connected by fusion welding.
➤ examples of incorrect and correct installation of electrical bridge common problems: the sprinkler head is too close to the electrical bridge, and water will be sprayed in the electrical bridge.
The nozzle of the conduit shall be sealed after passing through insulated wires and cables.
➤ installation example of electrical bridge grounding jumper; the cross-sectional area of jumper copper conductor is greater than 4mm ²， And it should span the bolt holes at both ends of the bridge connection.
Wrong opening at the bottom of the Bridge II conduit section 12.1.1 the metal conduit shall be reliably connected with the protective conductor and shall comply with the following provisions: 1.
(2) Promote the application of BIM Technology, comprehensively consider and plan the installation disciplines, especially for some key parts, such as machine rooms and basements, which need BIM software to accurately locate equipment, pipelines and components.
Correct installation: keep a safe distance between the electrical bridge and the sprinkler head.
3.
➤ installation example of electric bridge through deformation joint common installation problems of electric bridge through deformation joint: ① bridge expansion joint and building deformation joint dislocation; ② The electrical bridge should not be installed directly below the water pipe.
When the protective bonding conductor is not bridged between the galvanized ladder, tray and slot box body, each end of the connecting plate should not be less than 2 connecting and fixing bolts with anti loose nuts or anti loose washers.
Both ends of the joint of galvanized steel conduit, flexible metal conduit and flexible metal conduit should be fixed with special grounding clamps to protect the bonding conductors.
For buried steel conduit, the buried depth shall meet the design requirements, and the wall thickness of the steel conduit shall be greater than 2mm.
