What are the general regulations for the installation of cable trays

1. When the cable tray is laid in the technical layer of various pipelines of related specialties and the ceiling of the upper part of the corridor, the distance between the bridge and the water supply pipeline and the air duct often cannot meet the requirements of the specification, and it is not convenient to open the cover plate of the bridge when maintenance is required. During the installation process, it is difficult to control if the relevant professional cooperation and technical data of the relevant professional pipelines are not done in advance. Regarding this work, can we draw a simple diagram in advance, the technical data of the integrated pipeline and the location of the bridge, the cross-section diagram of the size of each other, and reasonably adjust the distance between the professional pipelines to prevent the occurrence of common problems.

2. The filling rate of the cable in the tray exceeds the standard value. In the construction drawings, the most common only floor plan, even if there is a section is not very perfect, in accordance with the "steel cable tray engineering design code" article stipulates: its design content has:

1. Floor plan of the bridge system; 2. Relevant cross-sectional drawings of the bridge system; 3. The name and quantity of the pallet, ladder frame, straight section, bend, support and hanger required by the bridge system and the necessary description; 4. Non-standard technical descriptions or auspicious drawings with special requirements. Due to the imperfect design and other reasons, the local appearance of the placement of the cable too much, and even the phenomenon of full load, does not meet the provisions of the specification: the filling rate of the cable should not exceed the specified value of the relevant standard, the power cable 40, the requirements of the control cable 50.

In this regard, the supervisors should do a good job of pre-control measures, strictly require the construction unit to master the use of electrical engineering systems before purchasing the bridge, and make accurate statistics on the number of cables and cable sections in each bridge, and find that the specifications of the bridge should be changed in time with the design to effectively control the occurrence of quality problems.

3. The cable laid in the cable tray is not fixed and the cable is not marked: according to the specification: when the cable is laid vertically, it is fixed every 1 place, and the head and tail ends of the cable, the turning and straight sections are fixed every 5-10m when the cable is laid horizontally; The specification states:

At the beginning, end, turn and branch of the cable, there are signs (cable number, model specification), etc.

1) The cable tray and trunking should be laid in a short and short direction, and should be laid along the wall, along the column or along the beam as far as possible.

2) According to the direction of cable tray and trunking laying, the position and load of the embedded steel plate required are proposed to the civil engineering professional and structural professional when the reserved wall hole, floor hole and hanger are installed. And it should be coordinated with the technology profession, the plumbing profession and the power profession.

3) The concealed metal trunking wiring in the ground should be closely coordinated with the civil engineering profession in the design, so as to reasonably determine the line path and equipment selection according to different structural types and building layouts.

4) Cables with different voltages and different purposes should not be laid in the same layer of cable trays

1) Cables above 1kV and 1kV and below;

2) Dual-circuit cable with the same path supplying power to the primary load;

3) Cables for emergency lighting and other lighting;

4) Power, control and telecommunications cables. If different grades of cables are laid in the same cable tray, a partition should be added to isolate the middle.

5) When the installation or maintenance under engineering conditions does not need to consider the additional concentrated load, the working load of the cable ladder frame and tray is evenly distributed according to the weight of the cable.

6) The requirement for the installation of the cable tray in the engineering design is that the cable tray should not be laid in parallel with the following pipelines, and when it cannot be avoided, the position of the cable tray should meet the following regulations, or take corresponding protective measures.

1) The cable tray should be above the pipe with corrosive liquid.

2) The cable tray should be under the thermal pipe.

3) When the flammable and explosive gas is heavier than air, the cable tray should be above the pipeline.

4) When flammable and explosive gases are lighter than air, the cable tray should be under the pipeline.

7) The minimum distance between the cable tray and the pipeline is shown in the relevant standards.

8) The necessary distance should be maintained between the integrated wiring cable and the nearby electrical equipment such as motors and power transformers that may generate high-level electromagnetic interference. The spacing between the integrated wiring cable and the power cable shall comply with the provisions of GB T 50311-2000 specification.

9) The spacing between the integrated wiring cables, optical cables and pipelines laid on the wall and other pipelines shall comply with the provisions of GB T 50311-2000 specification.

10) When the cable tray is laid horizontally, it is advisable to select the best span according to the load curve for support, and the span is generally. When laying vertically, its fixed spacing should not be greater than 2m

1 General Provisions.

1 1 This chapter is applicable to the new and expanded general industrial and civil building cables, bridge installation and cable laying in the bridge 100 frame with a voltage of 10kV and below.

1 degree 2 cable tray installation and cable laying in the tray shall be constructed in accordance with the approved design documents.

1 3 The pallet (slot) or ladder frame straight section supported by the support, hanging, and bracket is combined, and the curved non-straight section is combined, and the rigid structural system with continuity of the cable is the cable tray.

The metal cable tray and its bracket and the metal cable duct that is introduced or led out must be grounded (PE) or zero (PEN) reliably and must comply with the following requirements:

1. The total length of the metal cable tray and bracket shall be connected to the grounding (PE) or zero (PEN) trunk at no less than 2 places;

2. The two ends of the connecting plate between the non-galvanized cable tray are connected to the copper core grounding wire, and the minimum allowable cross-sectional area of the grounding wire is not less than 4mm2;

3. The two ends of the connecting plate between the galvanized cable tray shall not be connected to the grounding wire, but there shall be no less than 2 connecting fixing bolts with locknuts or washers at both ends of the connecting plate. Genus.

1 5 It is strictly forbidden to have defects such as twisting, armor flattening, sheath fracture and serious scratches on the surface of cable laying.

1 6 If there is a place with fire protection requirements at the cable tray, fire isolation measures should be taken.

Precautions for installing cable trays:

1.Before we choose the cable tray, we need to pay attention to the construction environment, in the selection of the cable tray that is suitable for the construction environment, if the cable tray we choose does not meet the environmental needs, then the cable tray will be seriously damaged by the environment after installation, and the entire line will be damaged.

2.Once the cable tray is installed, these requirements should be met when the main grounding circuit needs to be connected. The resistance connected at both ends of the cable tray should not be greater than ohms, and the grounding hole needs to de-energize the insulation layer.

When cutting off the power supply, the cross-sectional area in the direction of the size of the cable tray should not be less than the specified value.

3.When the fire protection requirements are required in the construction environment, the corresponding fireproof cable tray can be selected, and the overall fire performance requirements of the fireproof cable tray need to meet the requirements of the national light code or standard.

4.When you select a load class for a cable tray, the average load of the cable tray should not be greater than the rated average load of the selected cable tray. When the actual span of the cable tray support and hanger is not equal to 2m, the average working load should meet the requirements.

5.When the grounding trunk is laid along the full length of the bridge, at least part of the bridge (including non-straight sections) should be reliably connected to the grounding trunk.

6.When the grounding trunk is laid along the full length of the bridge, at least part of the bridge (including non-straight sections) should be reliably connected to the grounding trunk.

7.For the vibrating part, a spring coil should be installed at the connection of the grounding part.

The bridge is commonly used in the following ways: 1. The new boltless bridge is a lightweight, modular, simplified and energy-saving new commodity, a new technology commodity that saves time and materials, and a replacement commodity for the bridge. 2. The cascade bridge has the advantages of light weight, low cost, convenient device, easy heat dissipation and good ventilation.

It is suitable for the laying of cables with large diameters, especially for the laying of high-voltage and low-voltage power cables. 3. The large-span bridge has trough type, step type tray type. It is mainly suitable for use in places with a large span of room surface and interior.

Features: large load, large span, high strength, light structure, simple construction. The long-span cable tray is the third generation of the tray.

4. Pallet bridge is a widely used one in petroleum, chemical industry, light industry, television, telecommunications, etc. It has the advantages of light weight, large load, beautiful appearance, simple structure and convenient installation. It is suitable not only for the installation of power cables, but also for the laying of control cables.

The installation position of the cable tray should be according to the design drawing. However, most of the design drawings have neither planar coordinate position nor elevation calling. Therefore, it must be determined according to the actual situation of the project.

Shanghai Changpeng Metal Tray The following principles should generally be mastered: Cable tray should be kept away from pipelines and equipment with high-pressure or high-temperature gases (liquids). The cable tray should be kept away from corrosive gas (liquid) pipes.

On the process pipe gallery frame, the bridge should be installed on the side of the process pipeline as much as possible to facilitate the laying of cables and maintenance parts. The net distance between the bridge and the wall and the top should be determined according to the size and number of cables in the bridge, and the operation space should be ensured. The ceiling should not be less than 150mm.

1. The dirt and water in the trough should be eliminated before the bridge wiring;

2. Before the cable is deployed, the model specifications, programs, routes and locations should be checked to be consistent with the design regulations. The sum of the cross-sectional area of the conductors, including insulation, in the same tray should not exceed 40% of the internal cross-sectional area;

3. The layout of the cable should be straight, and there should be no twisting, looping and other phenomena, and it should not be squeezed and damaged by external forces;

4. The two ends of the cable should be labeled before deployment to indicate the starting and ending positions, and the label writing should be clear, upright and correct;

5. Power cables, signal cables, twisted pair cables, optical cables and cables of other weak current systems in the building should be separated and deployed. The minimum clear distance between each cable should meet the design requirements;

6. There should be redundancy when the cable is deployed. In the handover room, the length of the twisted pair cable between the equipment is reserved, generally 3 to 6 meters; The working area is to meters; The reserved length of the optical cable at the equipment end is generally 5 to 10 meters; If there are special requirements, the length shall be reserved according to the design requirements;

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