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...

Due to changes in ambient temperature, steel cable trays will expand and contract with heat. Outdoor bridges are significantly affected by temperature variations. For example, if the maximum ambient temperature is 40°C and the minimum temperature is -20°C, the maximum thermal contraction of the cable tray can be calculated as follows: ΔL = 11.2 × 10⁻⁶ × 60°C × 1000 mm This leads to the following conclusions: When the temperature difference is 60°C, ΔL = 0.672 mm/m When the temperature difference is 50°C, ΔL = 0.560 mm/m When the temperature difference is 40°C, ΔL = 0.448 mm/m In engineering design, expansion joints should be incorporated for cable trays in straight sections. The recommended spacing for expansion joints is as follows: 50 m when the temperature difference is 40°C 40 m when the temperature difference is 50°C

The cable tray can be divided into grid type, ladder type, tray type and trough type according to its shape. A structural system with a certain rigidity.