1. The arrangement of cable tray layers is from top to bottom: computer cable tray, shielded cable tray, general control cable tray, low-voltage power and lighting cable tray, high-voltage cable tray. In the same tray, if two cables of different purposes must be placed, the tray shall be separated by partition and covered.
2. In order to facilitate maintenance and installation, the total width of tray on the same layer should not exceed 2m, and the distance between layers of tray is generally 300real.
3. The distance between the side of cable tray and the wall is 50-100mm, and the edge distance between the horizontal adjacent trays is 50mra.
4. The distance between the bottom of vertical tray of cable tray and the wall and column is 25-50mm; the distance between the top of tray and the bottom of ceiling, beam and other obstacles is more than 150 mm. If the distance between the bottom of the tray and the top of the electrical device is less than 450mm, a non combustible partition must be set at the bottom of the tray.
5. The span between cable tray supports is generally less than 3m, and the actual project is usually 15m or 2m. The bracket bracket and column are usually fixed by expansion bolts. The fixed position and strength are determined by calculation. In order to prevent drilling into the reinforcement during drilling, the reinforcement detector can be used for inspection in advance. Avoid the main reinforcement as much as possible. For places where brackets are used in cable trenches or cable tunnels, embedded parts shall be used as much as possible, and expansion bolts shall not be used. Generally, the embedded parts are flat steel with thickness of 8-16mm and width of 80-200ram, and the bracket arm is directly welded on the flat steel.
6 the installation path of cable tray shall be selected to avoid the process equipment or high-temperature pipeline that may produce high temperature as far as possible; if necessary, heat insulation baffle shall be added.
7. Generally, cross-linked cable and all plastic cable are used. During construction, roller shall be applied to the straight part of tray, while roller shall be used to assist setting out at the turning or appropriate position to reduce the friction between cable and tray and protect the cable sheath. When the cable is led from the main bracket to the electrical equipment, narrow tray or steel pipe should be selected for support protection.
8. The cables in the tray of cable tray shall be fixed with clamps or nylon straps. The fixed spacing is l.5-3m. For the single core cable with large cross-section in the same power circuit, it is better to place the finished product in a fixed shape. It is not allowed to bind single core cable with iron clip to avoid high temperature damage caused by eddy current.
9. When the cable bridge passes through the fire-resistant partition wall or baffle hole, the section of cable shall be fireproof. For example, brush anti-corrosion coating or seal the bridge with a metal shell filled with refractory materials. In order to prevent rain water erosion, a waterproof gradient of 1 / 100 is generally made from the inside to the outside of the building walls.
10. In order to ensure the safe operation of electrical lines, the cable tray system shall be well grounded. There are two specific methods: one is to connect all sections of the metal bridge with multiple strands of steel strand and then to ground; the other is to set up a neutral or grounding main line along the whole length of the bridge, and each tray at least has a reliable connection with it. Neutral connection or grounding branch line leading to electrical equipment.