Stepped Bridge

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

1. The routing of ladder-type cable trays and wireways should be short and direct, preferably 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 routes and equipment selection rationally determined according to different structural types and building layouts.

4. Cables of different voltages and purposes should not be laid 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 laid in the same cable tray, a partition should be added in between for isolation.

5. When no additional concentrated loads are considered for installation or maintenance under engineering conditions, the working uniformly distributed load of the ladder-type cable tray should be calculated based on the even distribution of the cable's self-weight.

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

(1) The cable tray should be above corrosive liquid pipelines.

(2) The cable tray should be below thermal pipelines.

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

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

(5) Refer to relevant standards for the minimum distance between cable trays and pipelines.

(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.