What should be the clearance between the bottom of the access floor and the top of the cable tray?

The recommended clearance between the bottom of the access floor and the top of the cable tray is 75 mm. This clearance is crucial for several reasons. It provides sufficient space for air circulation, which helps in maintaining an appropriate temperature for the cables. Proper airflow is essential in data centers and telecommunications environments where overheating can lead to equipment failure and decreased performance.

Additionally, a clearance of 75 mm allows for ease of maintenance and installation. Technicians need to have enough room to maneuver tools and equipment when performing installations or repairs on the cable tray without being hindered by limited space. This clearance also ensures that any potential obstructions or physical interferences are minimized, allowing for a more efficient setup and operation of the cabling infrastructure.

The other options—25 mm, 50 mm, and 100 mm—either do not provide adequate space for airflow and maintenance or exceed what is typically necessary for effective cable management practices.