Before laying the cable tray, check whether the cable tray is crossed or overlapped with other equipment and pipelines. Before construction, negotiate with each type of work, supervisor or construction unit and design unit, and make records to ensure smooth construction.
The cable traction shall be calculated according to the construction drawings or cables used in construction.
Precautions for bridge installation:
1. The length of the steel cable bridge in the straight section is more than 30m, and the length of the aluminum alloy or glass fiber reinforced plastic cable bridge is more than 15m. The expansion joint should be set up. The compensation device should be set at the place where the Xi'an bus duct crosses the expansion joint. The bridge with expansion joint can be used.
2. The bolts between the cable tray and the support and the cable tray connecting plate bolts are fastened without omission. The nuts are located outside the cable tray. When the aluminum alloy cable tray and the steel support are fixed, there are mutual insulation and anti-electrochemical measures for corrosion. Generally, asbestos pads can be used.
3. The cable tray laid in the shaft and crossing different fire zones shall be provided with fire isolation measures according to the design requirements. The cable tray laid in the electrical shaft can be fixed with angle steel.
4. When the cable tray passes through the firewall and fire floor, fire isolation measures shall be taken to prevent the fire from spreading along the line; For fire separation walls and plates, openings shall be reserved in coordination with civil construction. Edge protection angle steel shall be embedded at the openings. L50 shall be used according to the number of layers and pieces of cable laying during construction × fifty × 5 The angle steel is used as the fixing frame, and the fixing cabinet is welded on the edge protection angle steel at the same time; The frame can also be installed in the wall and slab during masonry or concrete pouring in the civil construction.
The connection resistance between the ends of the tray and ladder shall not be greater than 0.00033 Ω and shall be tested by equipotential bonding tester (continuity tester) or micro-ohm meter. The test of Xi'an bus duct shall be conducted on both sides of the connection point. The connection resistance at both ends of the whole bridge length shall not be greater than 0.5 Ω or determined by the design, otherwise the grounding point shall be added to meet the requirements. The coating shall be removed from the grounding hole, and the flat pad on one side of the bolt in contact with the coating shall use a special grounding washer with claws.
The expansion joint or soft joint shall be connected with braided copper wire. When laying the grounding trunk line along the whole length of the bridge, the tray and ladder of each section (including the non-linear section) shall be reliably connected with the grounding trunk line at least at one point; A spring washer shall be installed at the connection of the grounding part to avoid loosening.
Configuration of supports and hangers for cable tray and bus duct price
1. The short span of indoor support and hoisting is generally 1.5-3m. The mid-span of outdoor column is generally 6m.
2. The following principles shall be followed for the configuration of supports and hangers of non-linear sections. When the bridge width is less than 300mm, a support and hanger shall be set at the side of the straight section 300-600m away from the junction of the non-straight section and the straight line. When the bridge width is more than 300mm, in addition to meeting the following conditions, a support and hanger shall be added in the middle of the non-linear section.
3. The center distance between layers is 200250300350mm when the pultruded FRP cable tray is set in multiple layers.
4. 20-30mm expansion joint (metal bridge) shall be reserved every 50m in the straight section of the bridge.
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