In the engineering design, the layout of the bridge should be based on the comprehensive comparison of economic rationality, technical feasibility, operation safety and other factors to determine the scheme, but also fully meet the requirements of construction and installation, maintenance and cable laying.

桥架水平敷设时距地面的高度一般不低于于2.5m，垂直敷设时距地面1.8m以下部分应加金属盖板保护，但敷设在电气专用房间内时除外。电缆桥架水平敷设在设备夹层或马道且低于2．5m，应采取保护接地措施。

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 from the ground shall be protected by metal cover plate, except when it is laid in a special electrical room. If the cable tray is laid horizontally in the equipment mezzanine or catwalk and is less than 2.5m, protective grounding measures shall be taken.

桥架、线槽及其支吊架使用在有腐蚀性环境中，应采用耐腐蚀的刚性材料制造。或采取防腐蚀处理，防腐蚀处理方式应满足工程环境和耐久性的要求。对耐腐蚀性能要求较高或要求洁净的场所，宜选用铝合金电缆桥架。

Bridge, trunking and their supports and hangers shall be made of corrosion-resistant rigid materials when used in corrosive environment. Or adopt anti-corrosion treatment, which shall meet the requirements of engineering environment and durability. Aluminum alloy cable tray should be selected for places with high corrosion resistance or clean requirements.

桥架在有防火要求的区段内，可在电缆梯架，托盘内添加具有耐火或难燃性能的板，网等材料构成封闭或半封闭式结构，并采取在桥架及其支吊架表面涂刷防火涂层等措施。其整体耐火性能应满足有关规范或标准的要求。在工程防火要求较高的场所不宜采用铝合金电缆桥架。

In the section with fire protection requirements, the cable ladder and tray can be added with fire-resistant or flame-retardant board, net and other materials to form a closed or semi closed structure, and the fire-resistant coating shall be applied on the surface of the bridge and its supports and hangers. The overall fire resistance performance should meet the requirements of relevant national codes or standards. Aluminum alloy cable tray should not be used in places with high fire protection requirements.

电缆桥架作为布线工程的一个配套项目，尚无专门的规范指导，各生产厂家的规格形式缺乏通用性，因此，设计选型过程应根据电气各个系统的电缆类型、数量，合理选定适用的桥架。

As a supporting project of wiring engineering, there is no special specification guidance for cable tray, and the specification form of each manufacturer is lack of universality. Therefore, the design and selection process should reasonably select the suitable cable tray according to the type and quantity of cables in each electrical system.

(1)确定方向：根据建筑平面布置图，结合空调管线和电气管线等设置情况、方便维修，以及电缆路由的疏密来确定电缆桥架的路线。在室内，尽可能沿建筑物的墙、柱、梁及楼板架设，如需利用综合管廊架设时，则应在管道一侧或上方平行架设，并考虑引下线和分支线尽量避免交叉，如无其它管架借用，则需自设立(支)柱。

(1) Determine the direction: according to the building layout plan, combined with the air conditioning pipeline and electrical pipeline setting, convenient maintenance, and cable routing density to determine the cable tray route. Indoors, it shall be erected along the wall, column, beam and floor of the building as far as possible. If it is necessary to use the comprehensive pipe gallery for erection, it shall be erected in parallel on one side or above the pipe, and the down lead and branch line shall be considered to avoid crossing as far as possible. If there is no other pipe rack to borrow, it is necessary to set up (support) column by itself.

(3)确定桥架的宽度：根据布放电缆条数、电缆直径及电缆的间距来确定电缆桥架的型号、规格，托臂的长度，支柱的长度、间距，桥架的宽度和层数。

(3) Determine the width of cable tray: determine the model and specification of cable tray, the length of bracket, the length and spacing of pillar, the width and number of layers of cable tray according to the number of cables, cable diameter and cable spacing.

电缆桥架分为槽式、托盘式和梯架式、网格式等结构，由支架、托臂和安装附件等组成。建筑物内桥架可以独立架设，也可以敷设在各种建(构)筑物和管廊支架上，应体现结构简单，造型美观、配置灵活和维修方便等特点，全部零件均需进行镀锌处理，安装在建筑物外露天的桥架。

Cable tray is divided into trough type, tray type, ladder type and grid structure, which is composed of bracket, bracket and installation accessories. The bridge in the building can be erected independently or laid on various buildings (structures) and pipe gallery supports. It should reflect the characteristics of simple structure, beautiful appearance, flexible configuration and convenient maintenance. All parts should be galvanized and installed on the bridge outside the building.