Type selection design of cable tray: strong and weak current lines shall be laid in separate slots. When strong and weak current intersect in junction boxes (boxes), metal separation plates must be used to separate them. Strong and weak current conductors shall not be directly contacted in the slot. Various wiring in the ground trunking can only be connected at the outlet of the junction box. During the construction and installation of ground trunking, all trunking pipes are required to be connected into a reliable grounding whole.
1. Measurement and positioning:
Mark the installation position of the bridge with the snap line method, determine the fixed position of the support and mark it. The installation datum line shall be determined by the hanging steel wire method for the positioning of the bridge in the shaft. If the reserved hole is inappropriate, it shall be adjusted in time and repaired.
2. Fabrication and installation of cable tray
We locate according to the design elevation of the construction drawing and the specification of the bridge, and then make the support according to the measured size for industrialized production. Where there is no ceiling, it shall be hoisted along the beam bottom or installed by the wall support, and where there is ceiling, it shall be hoisted in the ceiling or installed by the wall support. In public places without suspended ceiling, combined with structural components and considering the beauty of the building and convenient maintenance, it shall be installed against the wall, column support or on the lower chord components of roof truss. The support installed against the wall shall be fixed with expansion bolts, and the spacing between supports shall not exceed 2m. Supports and hangers shall be added at the connection of linear section and non-linear section, at the deformation joint of building and in the middle of non-linear section with bending radius greater than 300mm. The installation of supports and hangers shall ensure that the levelness or verticality of bridge meets the requirements.
3. Grounding treatment
The grounding treatment of cable tray can use galvanized connecting plate as jumper between galvanized trays to connect the trays into one. Galvanized spring washers shall be added to the two connecting bolts at both ends of the connecting plate. The bridge shall be bridged with soft copper wire of no less than 4mm2, and then the bridge shall be connected with the grounding wire to form an electrical path. There shall be at least two connections between the whole bridge and the grounding main line.
4. Multi layer bridge installation; Layered bridge installation
Install the upper layer first and then the lower layer. The distance between the upper and lower layers shall be reserved to facilitate cable laying and maintenance in the later stage. The clear distance between horizontal adjacent bridges shall not be less than 50mm, the distance between layers shall not be less than 150mm according to the bridge width, and the distance from weak current cable bridge shall not be less than 0.5m.