机电安装里非常不起眼、却非常容易被砍预算的，就是天花板上面那几条金属槽。很多项目电缆没坏，桥架先挠了、锈了、弱电被强电搅了。

The most inconspicuous but easily cut budget in mechanical and electrical installation are the few metal slots on the ceiling. Many projects have cables that are not damaged, but the cable trays are scratched, rusted, and weak electricity is disturbed by strong electricity.

选型先分结构，别全按“盒子”买：

Choose the structure first, don't buy everything by "box":

梯式：像梯子，散热非常好、单价低，适合大截面动力电缆主干；细控制线别直接丢进去，会卡横档。

Ladder style: Similar to a ladder, it has the best heat dissipation and low unit price, suitable for large section power cable trunks; Don't throw the fine control line directly into it, it will get stuck in the crossbar.

托盘式：带孔底板，动力+控制混敷非常常用，兼顾散热和防尘。

Tray type: perforated bottom plate, most commonly used for power and control mixed application, balancing heat dissipation and dust prevention.

槽式：全封闭带盖板，计算机、消防、通信这类怕干扰的弱电专路闭眼选它。

Slot type: Fully enclosed with cover plate, suitable for weak current circuits such as computers, fire protection, and communication that are afraid of interference.

再按环境挑“皮肤”：

Select 'Skin' again based on the environment:

室内干燥：冷镀锌或喷塑够用。

Indoor drying: Cold galvanizing or spray coating is sufficient.

地下室、户外、管廊：热浸锌锌层≥65μm，潮湿重腐蚀环境拉到85μm以上。

Basement, outdoor, and pipe gallery: hot-dip zinc coating ≥ 65 μ m, and in humid and heavily corrosive environments, it can reach 85 μ m or more.

化工、沿海：直接304/316L或玻璃钢，别拿普通镀锌硬顶。

Chemical and coastal industries: directly use 304/316L or fiberglass, do not use ordinary galvanized hardtop.

消防回路和穿越防火分区：用防火桥架+防火泥封堵，别以为“金属不怕烧”。

Fire protection circuits and crossing fire compartments: Use fireproof bridge frames and fireproof mud to seal them, don't think that "metal is not afraid of burning".

三个现场必查点：

Three on-site inspection points:

板厚拿卡尺抽。标1.5mm实测1.2mm的太多了，跨距一大中段下挠，电缆受力变形。

Use a caliper to measure the thickness of the board. There are too many 1.2mm cables measured with a standard of 1.5mm, and the middle section of the span is bent downwards, causing deformation of the cable under stress.

支架间距别自作主张放大。常规1.5~2m一跨，弯通、三通、端头30~50cm内建议加支架；钢制直线段超30m、铝合金超15m要留伸缩节，穿建筑沉降缝建议断开补偿。

Do not arbitrarily increase the spacing between brackets. A standard span of 1.5-2m is required, and brackets must be added within 30-50cm of bends, tees, and ends; Expansion joints must be left for steel straight sections exceeding 30m and aluminum alloy sections exceeding 15m, and compensation must be disconnected when passing through building settlement joints.

填充率守住红线。动力电缆≤40%、控制电缆≤50%，再留20%扩容余量；强弱电同槽一定加金属隔板。

Fill rate holds the red line. Power cables ≤ 40%, control cables ≤ 50%, with an additional 20% expansion allowance; Metal partitions must be added when strong and weak electricity are in the same slot.

顺手记一条验收红线：到场先试装一节，看连接片孔位、盖板卡扣、螺栓防松垫圈齐不齐。主材省两百，配件缺一套，后期接地测试过不了，返工钱够买三批桥架。

Take a note of the acceptance red line: First, try installing one section on site to check if the connection holes, cover plate buckles, and bolt locking washers are aligned. Save 200 yuan on main materials, one set of accessories is missing, and the grounding test cannot pass later. The rework money is enough to buy three batches of cable trays.

把“结构看电缆类型、防腐看环境、支架看跨距”这三句钉在采购单上，隐蔽工程验收会少一半扯皮。

Nail the three sentences of "structure depends on cable type, anti-corrosion depends on environment, and support depends on span" on the purchase order, and the acceptance of concealed works will be reduced by half.