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Distribution box cable trough cable joint distribution box trough
abstract
Edit this section | Return to the top bridge to edit this section | Return to the top selection 1. 1. In engineering design, the bridge layout should be comprehensively compared according to economic rationality, technical feasibility, operational safety and other factors to determine the best scheme, and fully meet the requirements of construction, installation, maintenance and cable laying.
1.2 When the bridge is laid horizontally, the height from the ground is generally not less than 2.5m When it is laid vertically, the part below 1.8m should be protected by metal cover plates, except when it is laid in a special electrical room. When the cable tray is laid horizontally on the equipment interlayer or artificial path and is less than 2.5m, protective grounding measures should be taken.
1.3 when the bridge, trunking and its supports and hangers are used in corrosive environment, they should be made of corrosion-resistant rigid materials, or treated with anti-corrosion treatment that meets the engineering requirements.
Environmental and durability requirements. Aluminum cable tray is used in places with high requirements for corrosion resistance or cleanliness.
1.4 In the section with fire prevention requirements, fire-resistant or flame-retardant plates, nets and other materials can be added to the cable ladder and bridge frame to form a closed or semi-closed structure.
Measures such as painting fire retardant coatings on the surface of bridges and their supports and hangers. Its overall fire resistance should meet the requirements of relevant national codes or standards. Aluminum cable tray is not suitable for places with high fire protection requirements.
1.5 is used for cables that need to be shielded from electromagnetic interference, or when there are environmental requirements such as outdoor sunlight, oil pollution, corrosive liquid and flammable dust. No-hole tray cable tray should be selected.
1.6 Cable tray shall be covered where dust is easy to accumulate; It is suggested to add pads or use non-porous trays on the underpasses of public passages or outdoor street crossing sections.
1.7 Cables with different voltages and uses should not be laid in the same cable trough;
(1) Cables higher than 1 kV and lower than 1 kV:
(2) Double-ring cable and cable trough supply power to main load on the same path;
(3) emergency lighting and other lighting cables:
(4) Power, control and communication cables.
If cables of different grades are laid in the same cable trough, a partition should be added in the middle.
1.8 When the length of steel straight section exceeds 30m, the length of aluminum cable tray exceeds 15m, or the cable tray passes through the expansion joint (settlement joint) of the building, there should be a compensation allowance of O-30mm. Expansion connection plates shall be used.
1.9 The width and height of cable ladder and bridge frame shall meet the requirements of filling rate. In general, the filling rate of cables in ladders and trays should be 40%-50%, which should be controlled.
The cable can be 50%. 70%. In addition, l0%-252 engineering development allowance should be reserved.
1. 10 When selecting the load grade of cable tray, the working uniform load of cable tray should not be greater than the rated uniform load of the selected load grade of cable tray. If the bracket and hanger of the cable tray are solid,
When the international span is not equal to 2m, the uniformly distributed working load shall meet the following requirements:
Where qg -- work uniform load, kn/m;
QE- rated uniformly distributed load, kn/m;
LG- actual span, m.
Edit the rated uniformly distributed load level at the top of this paragraph | See table 1.
Table 1 Rated Uniform Load Grade of Cable Bridge
A
B
C
D
Rated uniformly distributed load (kn/m)
0.5
1.5
2.0
2.5
Table 2 Rated uniformly distributed load grade of aluminum cable tray
Load grade
A
A 1
B
C
D
Rated uniformly distributed load (kn/m)
0.5
1.0
1.5
2.0
2.5
Authoritative 0.0% professional 100.0% rich 0.0% good 0.0% poor 0.0%
Cable bridge, bridge, hot-dip galvanized bridge, stainless steel bridge