Last fall, we featured a blog on raised floors by guest blogger Chris Ouellette, a Senior IT Specialist of Data Centre Services for IBM Canada, Ltd.


Chris did an excellent job at covering some of the key reasons why doing away with raised floors in the data center isn’t as straight forward as one might think.

As a follow up to that blog, I thought we’d take a look at some of the other drivers moving cabling out of the floor and overhead.

Out of Sight, Out of Mind

Whether it’s your laundry room, a kitchen cupboard or the junk drawer, let’s face it—when the clutter is out of sight, it’s out of mind. The raised-floor is no different.

With so many changes and equipment turnover in today’s data center, new cable runs are added on a regular basis. And due to poor access and visibility, it isn’t always easy to properly identify and remove unused cables from the underfloor space. In fact, according to some surveys, data center managers estimate that more than 50% of the cables under the floor are unused. Overtime, one look under the raised floor can bring back memories of last night’s spaghetti dinner.

Consequently, cable accumulation is the number one factor contributing to the inefficiency of a traditional raised floor. Not only does the build-up of cable under the floor block airflow and impact CRAC performance, but it can also be a violation of the NEC in terms of abandoned cable requirements and maintaining proper separation of power and data cables.

But it’s not just data cables that can cause problems. With more equipment in the data center than ever, we’re also seeing a significant increase in the number of power circuits under the floor that can also block air flow and increase the risk for hot spots due to uneven pressure.

In high-density, high-heat environments, extreme hot spots are especially a concern during maintenance when pressure forces the cold air out of open tiles. Besides, there are plenty of cost-effective overhead busway power distribution solutions now available.

Too Much Weight

As density continues to increase, racks and cabinets have gotten taller, and data center managers are loading them right up. What used to be the 800 pound gorilla in the room is now reaching upwards of a ton. And when cabinets start to weigh that much, they can impact the structural integrity of the raised floor if floor loading requirements are exceeded.

Having too much cabling under the floor also makes it extremely difficult to add reinforcements when necessary. Furthermore, the more you open up the raised floor, the more you run the risk of preventing proper weight distribution and further impacting the structural integrity.

On-slab floors give peace of mind that your equipment isn’t going to fall down a hole, not to mention something to anchor to in high seismic areas. They also facilitate rolling all that heavy equipment around.

Advances in Multifiber Connectivity

Plenty More to Consider

While overhead ladder racks can make it easier to access cables, and they don’t impact airflow in the floor, that’s not to say that raised floors don’t have their place. Hands down, the raised floor is better equipped to support liquid cooling systems, and they do offer more flexibility for those tasked with frequent rack rearrangement.

And let’s not forget that overhead cabling has its own considerations—working from ladders, higher temperatures, and the need to always maintain aesthetics. You can’t just put the tile back and forget about it.

While installing cabling overhead is still considered easier than under the floor, it is also important to ensure that the overhead cabling system (and the overall configuration of the data center) is designed in way that prevents having too much cabling in one ladder rack, which can adversely impact hot air return. It’s also important to coordinate the design of the overhead cabling system with fire suppression and lighting systems.

At $20 to $25 per square foot, the potential cost of a raised floor is also something that should be factored in the equation. And greenfield installations that place cabling overhead will require far fewer openings in the floor and fewer air flow management solutions (i.e., grommets, brush seals and boots), which are costly to install and can increase the risk for leakage if not properly maintained.

Whether you choose to look up at your cables or look down, the experts at Belden are ready to support your needs. Designed and engineered for ease of installation, superior aesthetics and versatility, our wide range of Belden Networking Enclosures feature numerous top and bottom entry points for both configurations, and a rubber gland access on top to keep the dust out.