Bridge is a support and put the cable bracket. Bridge in the project with a very common, as long as the laying of cables to use the bridge, cable tray as a supporting project of cabling engineering, there is no specific specification to guide, each manufacturer's specifications program lack of universality, therefore, the design selection process should be based on the type of cable of each system of weak power, the number of reasonably selected for the applicable bridge. Cable tray has a full range of varieties, wide range of applications, high strength, light structure, low cost, simple construction, flexible wiring, installation standards, beautiful appearance and so on.

Second, the classification of the bridge:

According to the shape, it is divided into the following types:

1. grooved cable tray: grooved cable tray is a fully enclosed cable tray. It is most suitable for laying computer cables, communication cables, thermocouple cables and other highly sensitive systems such as control cables. It has a better effect on the shielding interference of control cables and heavy corrosion in the environment cable protection.

2. Tray type cable tray: Tray type cable tray is one of the most widely used in petroleum, chemical industry, light industry, telecommunication and so on. It has the advantages of light weight, large load, beautiful modelling, simple structure, easy installation. It is suitable for the installation of power cables, but also suitable for the laying of control cables.

3. Step type cable tray: step type cable tray is based on domestic and international information and improve the design. It has the advantages of light weight, low cost, distinctive modelling, easy installation, heat dissipation, good ventilation. He applies to the laying of cables with large diameter in general, and is suitable for laying of high and low voltage power cables.

4. Combined cable tray: Combined cable tray is a new type of bridge, is the second generation of cable tray series products. It is suitable for various projects, various units, various cable laying, it has a simple structure, flexible configuration, easy installation, novel form and so on.

5. net format cable tray: net format cable tray is suitable for electric power, communication cable wiring is done as an extension of the traditional bridge, cable tray raw materials for steel wire, welded and shaped, and finally surface treatment.

6. large span cable tray: the current large span cable tray is generally assembled from pultruded FRP profiles, suitable for power cables, control cables, lighting cables and accessories.