Good grounding through metal conduits reduces interference and improves the fire rating of cabling pathways in the server room. At the same time, using metal raceways as routing materials allows you to fully leverage their excellent expandability and ease of adding cables. The layout of raceways is generally arranged around the equipment.
With the increasingly common use of cabinets, running raceways parallel to rows of cabinets is worth considering. Typically, one raceway is arranged for each row of cabinets, or two adjacent rows can share a common raceway in the middle aisle. The former approach is generally more ideal.
For server rooms with raised floors, the common practice is to install raceways underneath the raised floor. However, with the widespread adoption of precision air conditioning using underfloor air delivery in high-end server rooms, this method has revealed many issues.
Since equipment is arranged in rows within the room, raceways are configured under the floor for each row. Generally, the height of these raceways is between 50 and 100 mm, while the installation height of the raised floor is only around 300 mm, which impacts the airflow of the air conditioning plenum. The more raceways there are, the worse the air delivery becomes (and there are often power raceways under the floor as well).
Moreover, placing cables, especially power cables, under the raised floor increases fire hazards. Electrical faults can ignite a fire, and such incidents under the floor are not easily detected quickly. Even if conventional fire-detection heat and smoke sensors are configured, their response is not rapid due to the underfloor airflow. There have been multiple fire incidents originating from under raised floors. Therefore, many server rooms, especially in the telecom industry, now commonly adopt overhead cable routing.
Overhead routing requires coordination with the equipment layout. This layout is mainly suitable for standard rack-mount configurations, and the cabinet dimensions, especially the height, should be generally consistent to ensure an aesthetic appearance.
Overhead routing uses raceways. There are two installation modes for raceways: suspended from the ceiling on brackets or supported on stands from the ground. Stands supported on the ground can easily clash with the cabinets, which should be noted during design.
Overhead raceways come in two forms: open ladder-type cable trays and enclosed types. Open ladder trays are the mainstream application. During design, the first step is still based on the overall cabinet layout plan of the server room, setting up one path per row of cabinets. The advantage