What precautions should be taken when wiring cable trays?

1、 Laying distance

When wiring the cable tray, attention should be paid to laying the cables inside the tray vertically at intervals of 1.50-2m above its upper end; When laying horizontally, the first and last ends of the cable, turns, and every 5-10m.

When several sets of cable trays are laid in parallel at the same height, protection and maintenance intervals should be considered between adjacent cable trays. When laying cable trays horizontally, the height from the ground should generally not be less than 2.50m. For vertical equipment, metal covers should be added to protect the parts below 1.80m from the ground, but when laying in electrical dedicated rooms (such as distribution rooms, electrical shafts, technical floors, etc.), they should be outside.

When laying cable trays horizontally, it is advisable to select the optimal span according to the load curve for support. The span is generally

1.5-3m, and the largest can also be made into a large-span tray of 8m. In addition, when laying vertically, the spacing between fixed points should not be greater than 2m.

Cables can be laid without gaps on the cable tray, and the filling rate of the cable in the cross section of the tray should not exceed 40% for power cables; The control cable should not be larger than half of itself. When the cable tray is parallel or intersecting with various pipelines, its minimum clear distance should comply with relevant national regulations.

2、 Abnormal cables or voltages cannot be laid on the same layer of cable tray

If there are cables with abnormal voltages above 1kV and below 1kV, dual power cables with the same path supplying power to the first level load, cables with abnormal uses for emergency lighting and other lighting, or strong and weak current cables, they should not be laid on the same layer of bridge. If the equipment is constrained by conditions and needs to be placed on the same layer of bridge, a partition should be used to isolate it.

3、 Protective methods

When selecting cable trays for indoor wiring, the cables should not have an outer protective layer of jute or other flammable materials; When selecting cable trays for wiring in areas with corrosion or rare humidity, corresponding protective methods should be adopted based on the abnormalities of the corrosive medium. If the tray is selected as a hot-dip galvanized tray with strong corrosion resistance, it is best to use plastic sheathed cables. Cable trays cannot be installed above corrosive gas and thermal pipelines or below corrosive liquid pipelines. If conditions are limited, anti-corrosion and insulation methods must be used.