Cable Tray Selection And Selection Considerations
1. in the project design, cable tray arrangement should be based on economic rationality, technical feasibility, safety and other factors to determine the best solution, but also to fully meet the requirements of construction, installation, maintenance, repair and cabling.
2. when laying cable trays horizontal height not less than 2.5M from the ground, when laid vertically from the ground 1.8M the following section should be added to the metal cover to protect, but except for laying in electrical rooms within. Cable trays horizontal laying equipment mezzanine or people on road and lower than the 2. 5M, protective measures should be taken.
3. cable trays, trunking and hanger for use in corrosive environments, rigid material that should be corrosion-resistant. Or take measures to prevent corrosion and anti-corrosion treatment should meet the requirements engineering environment and durability. Corrosion-resistant high performance requirements or require a clean place, suitable for aluminum cable tray.
4. cable trays in the fire sector, cable ladder, tray with fire-resistant or flame retardant properties were added, and other material enclosed or semi-enclosed structure, and take in the tray and brush fire coating on the hanger and so on. The resistance should meet the requirements of relevant national norms or standards. In the engineering of high fire places. Not suitable for aluminum cable tray.
5. electromagnetic interference shielding of the cable lines. Or have a protective outer shadow n to outdoor sunlight, oil, corrosive liquids, combustible dust and other environmental requirements. Tray type cable tray without holes should be used.
6. easy accumulation of dust in places, cable tray cover should be used; in public or outdoors across the road. Bottom tray should be adding pads or use of non-porous pallets
7. different voltages, different uses of the cable should not be laid in the same layer within the cable tray:
(1) the above 1kV and below and 1kV cables:
(2) the same path to the load circuit in the power supply cable;
(3) emergency lighting and other lighting cable:
(4) electric power, control, and telecommunications cables.
If different levels when the cables in the same cable tray, intermediate partitions should be increased isolation.
8. when the steel cable tray line segment length over 30m, aluminum-alloy cable tray over 15m. Or when the cable bridge over the building expansion (settlement) joints should have a O-30mm compensation allowances. Connecting telescopic connection plate should be used.
9. cable ladder racks, pallet width and height of the selection, the fill rate requirements, cable ladder, tray fill rates in the General case, power cable 40%-50% control cable 50%. 70%. And to reserve l0% 1252 project development margin.
10. when selecting a cable tray load, cable tray uniform load should not exceed the selected cable tray load rated load if cable tray supports and hangers of the actual span is not equal to 2m.