Stepped Bridge

What are the key installation points for ladder-type cable trays?

1. The routing of ladder-type cable trays and wireways should be short and direct, preferably installed along walls, columns, or beams.

2. Based on the intended routing of cable trays and wireways, the civil and structural engineering disciplines should specify the locations and load requirements for reserved wall openings, floor openings, and embedded steel plates for hanger installation. Coordination with process, plumbing, and electrical disciplines is essential.

3. The wiring design for underground concealed metal wireways must be closely coordinated with civil engineering, with routing and equipment selection appropriately determined according to different structural types and building layouts.

4. Cables of different voltages and purposes should not be installed on the same layer of a cable tray:

(1) Cables above 1kV and below 1kV;

(2) Dual-circuit cables supplying power to primary loads on the same path;

(3) Emergency lighting and other lighting cables;

(4) Power, control, and telecommunication cables. If cables of different classes are installed in the same cable tray, a partition should be added in between for isolation.

5. When additional concentrated loads are not considered for installation or maintenance under engineering conditions, the working uniformly distributed load of the ladder-type cable tray shall be calculated based on the even distribution of cable weight.

6. Ladder-type cable trays should not be laid parallel to the following pipelines. If unavoidable, the location of the cable tray shall meet the following requirements, or corresponding protective measures shall be taken.

(1) Cable trays should be above corrosive liquid pipelines.

(2) Cable trays should be below thermal pipelines.

(3) When flammable and explosive gases are heavier than air, cable trays should be above the pipeline.

(4) When flammable and explosive gases are lighter than air, cable trays should be below the pipeline.

(5) For the minimum distance between cable trays and pipelines, refer to relevant standards.

(6) A necessary distance should be maintained between integrated wiring cables and electrical equipment that may generate high-level electromagnetic interference (such as motors and power transformers). The spacing between integrated wiring cables and power cables should comply with relevant regulations.

(7) The distance between integrated wiring cables, optical cables, and conduits installed on walls and other pipelines should conform to relevant regulations.