1. As a supporting project of the wiring project, the cable tray has no special normative guidance, and the specifications and forms of various manufacturers lack universality. Therefore, the design and selection process should be based on the type and quantity of cables of each electrical system. Reasonable selection and application bridge.
(1) Determine the direction: According to the floor plan of the building, combined with the setting of air-conditioning pipelines and electrical pipelines, convenient maintenance, and the density of cable routing to determine the best route for the cable tray. Indoors, it should be erected along the walls, columns, beams and floors of the building as much as possible. If the integrated pipe gallery needs to be erected, it should be erected in parallel on one side or above the pipeline, and the down-conductor and branch lines should be considered to avoid crossing as much as possible. If there are no other pipe racks to borrow, you need to set up (support) columns by yourself.
(2) Load calculation: Calculate the cable weight per unit length on the longitudinal section of the main line of the cable tray.
(3) Determine the width of the bridge: Determine the type and specification of the cable bridge, the length of the support arm, the length and spacing of the pillars, the width and the number of layers of the bridge according to the number of cables laid, the diameter of the cable and the spacing of the cables.
(4) Determine the installation method: Determine the fixing method of the bridge frame according to the setting conditions of the site, choose suspension type, vertical type, side wall type or hybrid type. The connecting pieces and fasteners are generally supplied together. In addition, according to the bridge frame Select the corresponding cover for the structure.
(5) Draw the plane and section drawings of the cable tray, and draw the space map for some parts, and list the material table.
2. If it is used in combination with the power cable tray, the power cable and the weak current cable should be straight on one side and separated by a partition in the middle.
3. When the weak current cable is used with other low voltage cables in the bridge, the weak current cable of the weak current system with the outer shielding layer should be strictly selected to avoid mutual interference.
2. Other installations
(1) When the cable tray enters the building from the outside, the outward slope of the tray shall not be less than 1/100.
(2) When the cable tray crosses with the electrical equipment, the clear distance between them shall not be less than 0.5m.
(3) When two sets of cable trays are laid in parallel at the same height, the clear distance between them shall not be less than 0.6m.
(4) Draw the route of the bridge on the parallel diagram, and indicate the coordinates or positioning size and elevation of the starting point, end point, turning point, branch point and lifting point of the bridge. will be more precise.
Straight line section: indicate the full length, the number of layers of the bridge, the elevation, the model and the specification.
Turning point and branch point: indicate the type and specification of the turning plate used.
Lifting section: indicate the change in elevation, and can also be represented by a local large sample drawing or section drawing.
(5) The supporting points of the bridge, such as columns, brackets or non-standard supports, the spacing, installation method, model specifications, and elevation of the bridge can be agreed to be listed on the plane, or can be marked in sections with different sections, single lines Figure or large-scale representation.
(6) The position of the cable lead-off point and the lead-off method. Generally speaking, a large number of cables can be led off by a vertical bending plate and a vertical lead frame, and a small number of cables can be led off by a guide plate or a lead pipe to indicate the lead-off method.
(7) The cable tray should be more than 2.2 meters above the ground, the distance between the top of the bridge and the ceiling or other obstacles should not be less than 0.3 meters, the width of the bridge should not be less than 0.1 meters, and the filling rate of the cross section in the bridge should not exceed 50%.
(8) When the cable is laid vertically in the cable tray, it should be fixed on the bracket of the tray at the upper end of the cable and at every interval of 1.5 meters. fixed at the meter.
(9) When setting in the suspended ceiling, the opening surface of the slot cover should maintain a vertical clearance of 80 mm, and the utilization rate of the section of the wire slot should not exceed 50%.
(10) The cables laid in the trunking can not be bound. The cables in the trunking should be straight and not crossed as much as possible. The cables should not overflow the trunking. The cables laid in the vertical trunking should be fixed on the cable support every 1.5 meters.
(11) When laying cables in horizontal and vertical bridges and vertical wire troughs, the cables should be bound. 4 pairs of cables are bundled with 24 cables, and backbone cables, optical cables and other signal cables of 25 pairs or more should be bundled according to the type of cable, cable diameter, and number of cable cores. The binding spacing should not be greater than 1.5 meters, the buckle spacing should be uniform, and the tightness should be moderate.
(12) When the bridge is laid horizontally, the support spacing is generally 1.5-3m, and the spacing fixed on the building structure when it is laid vertically should be less than 2m.
(13) When laying the metal trunking, set up the stand or hanger in the following cases: at the joint of the trunking; at a distance of 3m; 0.5m away from the two ports of the trunking; at the turning point.
5. Material statistics
(1) Bridge: Calculate the total length of various types and specifications of the bridge respectively, divide it by the standard length of the bridge to obtain the number of bridges, and add a margin of 1%-2%.
(2) Columns: If a uniform specification of columns is used, the total length of the bridge can be divided by the average column spacing to obtain the number of columns, and an additional 2% to 4% allowance can be added. If the column specifications are different, they need to be counted separately.
(3) Support arm: divide the total length of the bridge frame by the average spacing of the support arms, and add a margin of 1% to 2%, which is the total demand.
(4) Other parts: the total number is obtained by multiplying the number of main bodies by a certain proportion (depending on the factory).
