Better to Choose Underfloor Cabling? How to Build That?
Home Cabling Better to Choose Underfloor Cabling? How to Build That?

Better to Choose Underfloor Cabling? How to Build That?

Posted on by FS.COM

In today’s data center, when do the cable installation, one should consider not only the equipment operational efficiency, network performance, but also the ability to the future cable growth. To meet the good cable management, cables can be installed overhead or underfloor. The question is which one to choose and how to do that.


Factors to Consider for Selection
  • Vertical cable management types. Keep in mind of what types of vertical cable management you have. Consider what types of patch panels you have and whether horizontal cable managers are included or not.
  • Size of room and cabinets. According to TIA-942 (Telecommunications Industry Association), 7-foot racks and cabinets are allowed for a minimum 8.5-foot ceiling height above the finished floor. And it also makes the rule of 18 inches above the cable pathways for sprinklers, etc. So overhead cabling should be carried out in high-ceiling rooms. In addition, you should consider the size of cabinet heights, too. Make sure that all cabinets can be put into your room.
  • Tidiness. All cables are shown outside in the data center which applies overhead systems. Too many cables leave visiting people an impression of cable mess. While underfloor systems hide the cables and make a cleaner data center.
  • Cost. If you don’t have enough budget, then you can select the overhead system. The cost for the equipment and installation is less expensive. For example, the plenum cables are required in an underfloor system, which cost more than ordinary cables.

In reality, underfloor system seems to be more popular than overhead system because it is widely applied in data centers. If everything is ready for underfloor system, and more importantly, your budget also allows, you can choose the underfloor system. The following will tell how to build underfloor cabling system.

Underfloor Cabling Pathways Design

For cable routing design, basic principles should be followed.

First, separate the power cables from telecommunication cables. Before installing cables, you need to design where you electrical cables and telecommunications cables are run. Because these two kinds of cables should be separated to avoid electro-magnetic interference (EMI) and network performance degradation.

Second, well design cable pathways to increase the airflow. Heat can be easily generated by high-density equipment and power usage if the airflow is obstructed underfloor. Thus, you need to manage the data center airflow by using hot/cold aisles, getting containment right, or adding some cooling devices.

Third, stick to the ANSI (American National Standards Institute), TIA and EIA (Electronic Industries Alliance) standards.

The following figure shows a common data center with hot and cold aisles. The telecommunication cables run below the raised floor and to the rear of the cabinets, in the hot aisle. The power cables are run close to the floor in the cable tray located in the cold aisle. These two kinds of cables are separated. On one side, placing telecommunication cables below the raised floor is easy for cable maintenance in the future. On the other side, power cables placed close to the floor in the cold aisle is good for the airflow.


Cable Tray Design

The most common type of cable support in data centers is wire basket cable tray. Because wire basket is sturdy enough to support large number of cables and its open structure can provide adequate cable ventilation and is good for airflow. In the ANSI/TIA/EIA 942 standards, cable tray should have a maximum depth of 150 mm. If the cable trays are deeper than 150 mm, it’s not good for cable maintenance. Cable trays should be installed in multiple layers to provide spare capacity for future growth. The initial installation is always a single layer. If the initial cable tray structure were covered by the later cable layers, the initial cables can’t be accessed. So remember that the design should comply with the standard of the access to the base structures and the future cable growth.


Cable Tray Installation

In an ideal situation, the cable tray system should not affix itself to the raised floor. A support system that is independent from the floor structure eliminates unnecessary load and strain on the flooring grid.

Installing cable tray before installing the raised floor has many benefits, including reducing construction time.

Fiber and copper cables and other jointly used pathways should be separated by a fixed solid barrier of a material compatible with the cable tray to improve data center administration and operation. Cable trays should be sized to accommodate various equipment.

The tray system should be flexible enough to avoid the unforeseen obstructions under the raised floor such as chilled water pipes. And the vertical height of the tray should not be changed more than 1 inch in vertical per one foot of horizontal.


Overhead and underfloor cabling system are two methods for cable management in data centers. This article tells the factors to be considered when you determine which system to choose. It also shows how to design underfloor cabling pathways and cable trays installation to allow the equipment to operate at the best. Make sure you are familiar with all these important keys for creating an highly effective data center.

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