很多机电班组桥架本体买得没问题，卡尺量过、锌层也够，结果隐蔽验收那天被指着三处打回：支架晃、接地虚、穿墙洞没堵。这三处和桥架本身好不好没关系，全是“装”的账。

Many mechanical and electrical teams bought the bridge body without any problems, measured it with calipers, and had enough zinc layer. However, on the day of concealed inspection, they were pointed at three places and hit back: bracket shaking, weak grounding, and unobstructed wall holes. These three places have nothing to do with the quality of the bridge itself, they are all "installation" accounts.

先说支架。桥架挠不挠，一半在板厚、一半在托臂间距。水平直线段钢制桥架支架间距按荷载控制在1.5到3米，弯通、三通、端头30到50厘米内建议补一支独立支架，很多班组为了少打膨胀螺栓，把三通底下那支省了，重载一上，接头先下沉，盖板缝越拉越大。

Let's talk about the bracket first. The bridge frame is not flexible, with half of it in the thickness of the board and half in the spacing between the support arms. The spacing between the steel bridge brackets in the horizontal straight section is controlled within 1.5 to 3 meters according to the load. An independent bracket must be added within 30 to 50 centimeters of the bend, tee, and end. Many teams save the one under the tee to reduce the need for expansion bolts. When overloaded, the joint sinks first, and the cover plate seam becomes larger as it is pulled.

再说接地，这是非常容易被“看起来连上了”骗过的一项：

Speaking of grounding, it is the most easily fooled by "looking connected":

镀锌桥架不用另拉铜线，但每段连接板两端至少两颗带弹簧垫圈的防松螺栓，接触面要把漆层和氧化皮打磨掉。

Galvanized cable trays do not require additional copper wires, but each connecting plate should have at least two anti loosening bolts with spring washers at both ends, and the paint layer and oxide scale on the contact surface should be polished off.

非镀锌桥架建议在连接板两端跨接不小于4平方毫米的铜软线。

Non galvanized cable trays must be bridged with copper flexible wires of no less than 4 square millimeters at both ends of the connecting plate.

全长不管多长，至少两处和接地干线接通；超过30米每隔20到30米再加一点。

Regardless of the length, at least two points should be connected to the grounding main line; Add a little more every 20 to 30 meters beyond 30 meters.

用万用表量跨接点电阻，超过50毫欧每米就别凑合，后期雷击或漏电时整条桥架带电。

Measure the cross contact resistance with a multimeter. If it exceeds 50 milliohms per meter, do not compromise. In case of lightning strikes or leakage in the later stage, the entire bridge will be electrified.

第三个必卡点是防火封堵。桥架穿防火墙、穿楼板、进竖井，洞不能只把桥架塞进去就完事。防火桥架≠做了封堵，缝隙要用防火包打底、防火泥压面，厚度不小于墙或楼板厚。很多项目消防验收不过，不是桥架不防火，是那个洞没堵。

The third necessary checkpoint is fireproof sealing. Bridge passing through firewalls, floors, and vertical shafts cannot be completed simply by inserting the bridge into the hole. Fireproof cable tray ≠ has been sealed, and the gaps should be covered with fireproof wrapping and fireproof mud, with a thickness not less than the thickness of the wall or floor slab. Many projects fail the fire safety inspection, not because the bridge is not fireproof, but because the hole is not blocked.

顺手记两条现场红线：

Take note of two on-site red lines:

钢制直线段超过30米、铝合金超过15米，建议加伸缩节，间隙20到30毫米；过建筑沉降缝要断开做补偿，不然冬天热胀能把螺栓剪断。

Steel straight sections exceeding 30 meters and aluminum alloy sections exceeding 15 meters must be equipped with expansion joints with a gap of 20 to 30 millimeters; The settlement joint of the building should be disconnected for compensation, otherwise the bolts can be cut off by thermal expansion in winter.

螺栓螺母朝桥架外侧装，尖角别朝里，不然电缆放进去第一趟就被划破皮。

Install the bolts and nuts towards the outside of the bridge, with the sharp corners facing inward, otherwise the cable will be scratched on the first run.

把“支架补到三通底下、接地打磨测电阻、穿墙必封堵、伸缩节别忘”这四句写在班前交底里，隐蔽验收一次过，比桥架省两千块更有价值。

Write down the four sentences of "fixing the bracket under the three-way joint, grounding, polishing and measuring resistance, sealing the wall when passing through, and don't forget the expansion joint" in the pre shift briefing. Concealed acceptance can be done in one go, which is more valuable than saving two thousand yuan on cable trays.