Installation practices for extreme high density fiber cabling

Extreme high density fiber-optic cable meets the demand for exorbitant bandwidth. Installing these cables differs from traditional methods.

Extreme high density fiber-optic cable meets the demand for exorbitant bandwidth. Installing these cables differs from traditional methods.

The exorbitant bandwidth and connectivity demands for applications like data center interconnect have driven the development of fiber-optic cables with extremely high fiber counts. Today, cables with as many as 3,456 optical fibers are available. Research and development among cable manufacturers has resulted in the availability of cables with these very high fiber counts densely packed within the overall cablesheath.

Pathway space is always a consideration, and the ability to pack many fibers into a relatively small footprint is appealing. But such density affects the installation of these cables. This article overviews some of the high-density fiber-optic cables available today and their suppliers’ comments and recommendations regarding installationpractices.

RocketRibbon

Corning offers the RocketRibbon extreme density cable product line. Establishing the value proposition for cables of this type, the company explains, “Communications networks continue to evolve. More applications, more services, and more bandwidth—networks are being required to support more every day. To meet these demands, optical fiber is being deployed deeper into the network, supporting technologies such as fiber-to-the-home and 5G. At the same time, data center interconnect speeds are climbing. As a result, installations of more than 864 fibers, or extreme-density installations, are becoming common. But these extreme-density networks provide a new set of challenges to network operators and installers. Managing that volume of fiber requires attention to, and dedicated focus on, fiber management. Space management, especially in deployments where real estate is at a premium, is critical, as traditional solutions can be bulky. Installation deployment times, emergency restoration planning, and maintaining experience and knowledgeable installation personnel are also important factors when considering an extreme-densitynetwork.”

Corning’s 3,456-fiber RocketRibbon cable occupies approximately the same footprint as existing central tube and stranded ribbon tube design cables, the company says. “By leveraging our optical fiber cable design expertise, RocketRibbon cable allows operators to quickly install more capacity in the same duct space to accommodate increasing bandwidth demand,” Corning adds. “A unique ribbon subunit design makes the fibers within RocketRibbon cable easy to manage, identify, and trace—all of which significantly improves install times and lowers ongoing maintenancecosts.”

The cable consists of 288-fiber subunits, with up to 12 subunits per cable. Corning continues, “An extruded color-coding jacket protects and identifies each bundle and allows for direct and easy routing to splice trays, without the need for additional materials, ribboning processes, or furcationkits.”

Rollable Ribbon

OFS offers the Rollable Ribbon Cable product line, which includes the AccuFlex and AccuRiser brands. The company says these cables “offer the benefit of both flat fiber ribbons and loose fibers in one cable. The resulting cables require less space, allowing installers to double the density of existing pathways when compared to standard indoor cable designs. This capability is fueled by incorporating a new fiber ribbon technology from OFS into the cable—RollableRibbons.

“This new ultra-dense fiber technology uses a different optical fiber ribbon arrangement,” OFS continued, describing the Rollable Ribbon. “Each Rollable Ribbon consists of 12 optical fibers (250 µm) that are partially bonded together at selected points, causing the construction to take on a net-like appearance when the fibers are separated. These bonds allow the Rollable Ribbons to flatten into a traditional ribbon form for mass fusion splicing or to be rolled [compacted] and routed like individual fibers. This ability to route the ribbons similarly to individual fibers also offers the opportunity to use smaller, less-expensive splice trays and closures, which can also improve spaceconditions.”

Providing a density comparison, OFS says that an AccuRiser Rollable Ribbon Cable with 144 fibers has an outer diameter of 0.41 inches and a weight of 81 pounds per thousand feet. By comparison, a standard flat ribbon cable with 144 fibers has an outer diameter of 0.61 inches and a weight of 133 pounds per thousandfeet.

“With smaller diameters and lighter weights than typical cables, the AccuFlex Rollable Ribbon and AccuRiser Rollable Ribbon Cables improve both deployment speed and efficiency,” OFS says. “The gel-free cable designs help to lessen the time required for preparation and splicing. And these cables also offer increased efficiency in terms of splicing times by facilitating mass fusion, splice-in-place operations and even easier access and breakout to individual fibers for single splicing—two things that can help to get a new data center or building deployment up and runningquickly.”

Freeform Ribbon

Sumitomo Electric Lightwave offers a high-fiber-count cable line that incorporates its pliable Freeform Ribbon technology. The company explains, “Freeform Ribbon allows for dense fiber packing and a small cable diameter with a non-preferential bend axis, thereby increasing density in space-constrained applications. Sumitomo Electric’s patented pliable Freeform Ribbon construction is designed to both pack densely in small form factor cables while still being capable to transform quickly, by hand only, to splice-ready form similar to standard ribbon for fast and easy 12-count ribbonsplicing.”

Loren Rapp, product manager for Sumitomo Electric Lightwave’s fiber-optic cabling solutions line, explains more about this pliable ribbon technology in a document titled “Maximizing pathway efficiency in your network,” which appears on the company’s website. She states, “This type of ribbon has separations between groups of fibers that allow a ribbon to be flexible and roll onto itself. This technology is the answer to wasted space in central tube cables. Pliable ribbon technology allows for packing densities within cables similar to that of loose single fibers. However, where loose single fiber cables require substantial time and labor investment during the termination phase, especially with high-fiber-count applications, the pliable ribbon-based cables allow for rapid termination. The pliable ribbon easily transforms to flat ribbon for splicing operations. So splicing is not an issue since pliable ribbon can be spliced to other pliable ribbons—or it can be spliced to flat ribbons. It even can be quickly separated to individual fibers for single fiber splicing wheredesired.”

In addition to an 864-fiber Freeform Ribbon cable, Sumitomo also offers the 3,456-fiber Freeform Ribbon Slotted Core Ribbon Cable, which employs the pliable ribbon technology. This 3,456-fiber cable features 250-µm color-coded optical fibers “for easy fiber identification,” the company notes. “Freeform Ribbon enables high fiber density within a small cable diameter, which in turn helps with limited duct space. The 12-fiber ribbons enable connectorization with both MPO and all industry-standardconnectors.”

The company’s slotted-core ultra-high-fiber-count cables, introduced in 2016, also are available with 1,152 or 1,728fibers.

Spider Web Ribbon

The Wrapping Tube Cable product line from AFL incorporates the company’s Spider Web Ribbon technology, which the company introduced approximately five years ago. The company explains, “Spider Web Ribbon (SWR) is a bonded fiber design that allows for highly efficient ribbonizing applications or for individual fiber breakouts in preterminated optical assemblies. SWR provides the technology for a completely new generation of innovative cable designs. It consists of 12 fibers that are connected to each other by an intermittent UV-curable resin bond. The intermittent nature of the bond allows the ribbon to be bunched and collapsed similar to a bundle of loose fibers. It further lets the ribbon act as either a traditional ribbon for mass fusion splicing or be broken out into individual fibers for single fusion splicing. This feature of a collapsible ribbon allows for significant high-density fiber packages in outside plant and indoor-listed fiber-optic cable design. This means more fiber in smaller diameters that allows for significant cable diameter and weight reductions, which drive lower cost for installation and better utilization ofpathways.”

AFL dubbed its Wrapping Tube Cable “the first non-ribbon ribbon cable” when it introduced the product line. “Wrapping Tube Cable with SWR is an ultra-high-density outside plant cable designed specifically for fiber-to-the-home or access markets,” itsaid.

In a paper delivered at the International Wire and Cable Symposium in 2015, AFL application engineer Patrick Dobbins and cable engineering development manager Brett Villiger provided real-life scenarios in which the WTC cable design showed efficiency gains in installation projects. “In comparing the installation rate of WTC fiber-optic cable, the impact of smaller diameters and lighter weight helped in increasing the installation efficiency in both aerial cable installations and underground installations. Each location is unique and has many variables that can impact installation speed. … What was generally noted was that the impact was greatest on underground networks. Savings in time and cost for underground networks were noted in: reduced setup time due to significant weight reduction, decreasing cable transport cost, cable drum positioning and cable management time; quicker conduit proving time due to smaller rodding mandrel; quicker installation time due to less weight over existing cables, reducingfriction.

“The time saving on the underground projects that were measured with traditional loose tube and ribbon designs meant the installation crews could typically average 671 meters (2,202 feet) of cable per day. With the WTC cable design, the installation crew was able to average 745 meters (2,444 feet) per day on similar terrain and congestion. This is an 11 percent productivity increase for underground construction using the WTC fiber-opticcable.”

The authors also noted a 4.6-percent average productivity increase for aerialconstruction.

The cable types discussed in this article each use specific approaches to increasing fiber density. Although the resulting effects may be similar—i.e. ribbons that can be readily manipulated and terminated in the field—the manufacturing process for each cable differs, as do resulting handling and installation requirements for these cables. We at Cabling Installation & Maintenance encourage installers and users of these products—and all products in the cabling installation trade—to take advantage of the professional support and technical resources available to you from your supplier partners.

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