In a recent blog post, CommScope's manager for training and technology Eric Leichter offered some quick tips and laid out pros and cons of placing cables overhead or under a raised floor in a data center.
"We have seen a strong trend to place the low-voltage cabling overhead instead of underneath the cabinets," he said in his post, adding that such a decision about cabling actually is made with more than just the cabling in mind. "Creating an efficient heating/cooling system and overall implementation costs will be forefront in a designer's mind," he noted.
Nonetheless, Leichter lists pros and cons of overhead as well as under-raised-floor cable placement. Among the positives for overhead placement are less-expensive construction, ease of adding and tracing cables, and the separation of data cables from high-voltage cables. The cons of this approach include possible design complications caused by cabinet heights and ceiling fixtures. Likewise, underfloor placement has its pluses and minuses. Pluses include a clean appearance within the data center and cable pathways that are not exposed. Minuses include the potential for cables to block airflow, possible space constrcitions and some unintended consequences of removing a floor tile to access the cable.
The blog post also references the TIA-942 standard, reminding data center designers of what the standard says about ceiling height and pathway clearance.