VDV Support Selection: No Longer an Either/Or Choice

For voice/data/video (VDV) cabling installations, as with power installations, everyone—including electrical contractor and client—benefits from support systems that are easily installed overhead in a suspended ceiling or under a raised floor and readily accept cable initially and during later additions. Their user-friendly qualities may boost overall productivity to boot. Once, not so long ago, the options for support overhead or underfoot were limited to the standard types of two-sided rail cable trays or cable runways. Although these systems are still commonly used and have definite advantages in many applications, there are now numerous alternatives with various distinguishing characteristics and attributes. These alternatives include center spine supports, wire mesh baskets, bendable metal systems, flexible nylon mesh supports, J-hooks, and other wide-base supports. Before selecting one system over another for various jobs, it is worthwhile to note the broad particulars of each system and the intricacies of each manufacturer’s entry in a category. The specifier, who could be an engineer, communications consultant, or electrical contractor, has to take into account the nature of the application, what wires will be run, how many cables will be run, and the overall weight. Then, he or she needs to perform the calculations to determine the type of support best-suited to the project. The center spine trays, for example, are rated for up to 100 pounds per foot, with basket trays possibly rated as low as 20 pounds per foot of carrying weight or even less. And, unlike space needs for power installations, which are fairly constant or grow slowly, space needs for VDV installations seem to grow fast. So a support system that accommodates expansion (as well as additions) particularly easily might be much appreciated, perhaps repeated, over the long run. With respect to developing standards, things are, in many areas, in flux. For example, American National Standards Institute (ANSI) has recognized the Electronic Industry Alliance and Telecommunications Industry Association (EIA/TIA), as developers of standards, including those addressing support of Category 5 and above and fiber optic wiring. This standard, in turn, reflects information from the original manual produced by BICSI some years ago that addressed cabling installation methods. BICSI does not write standards; it is a nonprofit organization that promotes the education of the telecommunications industry through detailed manuals and certified training programs that are offered nationwide. NFPA 70 now has a specific chapter devoted to telecommunication systems. As these codes and standards continue to evolve or harmonize, the specifier’s job of selecting the right cable support system will become clearer. The following are some of the codes and standards that may apply to the cable support systems discussed in this article. NEMA VE-1 “Metal Cable Tray Systems” and NEMA VE-2 “Metal Cable Tray Installation Guidelines.” NEMA VE-1 and VE-2 are standards for defining, testing and installing cable trays, written by an association of cable tray manufacturers. NFPA 70 (National Electrical Code 1999) Article 318—Cable Trays, Article 250—Grouding and Bonding, Article 800—Communication Circuits. The NEC is the enforceable code for safety and protection of electrical systems. The articles listed above give the requirements for cable fill and grounding requirements. ANSI/TIA/EIA-569-A “Commercial Building Standard for Telecommunications Pathways and Spaces” is a performance standard that identifies the guidelines for routing and the support of cabling. Section 4.5 specifically addresses the use of cable trays in commercial pathways, (e.g., types of cable tray, cable fill, and support). This standard is currently under review for cable fill guidelines and to address the newer types of cable trays in this article. Center spine Featuring a central support with rungs on one or both sides of the spine, center spine cable tray generally installs from ceiling, floor, wall, or other permanently mounted structure relatively fast because it requires only one fastener per location rather than two. Depending upon configuration, center spine can provide one or two compartments and one or more levels of running support. The open design permits access to the tray from either side. The rungs are attached transversely through the top or the bottom of the center rail. Rung tips may vary among manufacturers, for various reasons including limiting or eliminating risk of cable damage during installation. Spacing of the rungs is determined by the support requirements. While most systems come pre-assembled, some are available unassembled, which could be handy if a job site is flush with obstructions that would require a lot of modification of the cable support. With center-hung trays, turns are usually just a matter of snapping on or otherwise attaching a connector onto the center spine and then slipping on the next section of tray headed in the new direction. Available either factory assembled or field assembled and from pre-marked spines (marked at 3-inch intervals) and separate rungs, Thomas & Betts modular aluminum Center-Lok Center-Spine Cable Tray can be mounted on the wall, ceiling, floor, or other permanent structure. It features integrated cable tie slots in the rungs, which facilitate organization of cabling through the rails. This allows separation of primary from secondary feeds and providing cable management for electromagnetic interference protection. Rungs can be spaced at various intervals down to every 3 inches (the spine markings are at 3-inch intervals) and up to three tiers are possible. Three spine sizes, a variety of rungs, and diverse accessories are available. As the components snap apart and together again, rung spacing can be easily reconfigured during retrofitting or later expansion, the company notes. Cooper B-Line Center-R-Rail System includes ceiling-hung or floor-mounted DATA-TRACK, ceiling-hung VERTI-RACK (featuring multiple tray runs with a center rail), and wall-supported or other structure-supported HALF-RACK and MULTI-TIER HALF-RACK straight sections, along with various tray connectors, auxiliary tray supports, and accessories. The MULTI-TIER HALF-RACK and VERTI-RACK are expandable after installation with ADD-A-RUNGs that attach to the bottom of existing trays. The lightweight, high-strength aluminum systems feature Qwik-Bolt splices that, according to the manufacturer, reduces the hardware required for connection, and may also be used to support the tray. The grid-design universal hub fittings enable installers to connect up to eight trays in various directions. MPHusky’s Centray, made of high-strength aluminum, is available, factory assembled, as top-, bottom-, or dual-width rung, and wall rack (with rungs on one side). The line offers an EZ-Clip coupling method of attachment of sections without nuts and bolts, using a wrap-around clip that, says the manufacturer, eliminates 60 percent of the labor normally associated with center spine type trays. The product features an extruded web down the length of the rung, which, the manufacturer said, results in a stronger rung that prevents bending and deflection. The rungs are chamfered, eliminating the need for end caps (unless the end caps are used for identification). The Wiremold Company has introduced FiberReady fittings for its SpecMate center-spine cable tray line. The vertical pivot connectors attach to the rungs of the tray, providing a 2-inch bend radius that is hospitable to VDV wires. Screw-in outer rungs can be removed and replaced for future expansion without removing the cables, notes the manufacturer. Mono-Systems, Inc.’s Mono-Tray center hung cable tray, with fixed rungs, is available in aluminum and steel, in various widths up through 24 inches, in a bottom- or top-rung configuration. A lightweight Mono-Tray Aluminum “L” series, suitable for lighter-duty applications, is also available, bottom or top rung. On the bottom-rung units, the spine divides the tray into two equal compartments. The top-rung design offers a single large-capacity compartment. The company also makes Mono-Tray Aluminum Removable Rung in top-rung and bottom-rung designs. PW Industries, Inc.’s CenterLine Center-Hung System, available in various configurations including bottom-mounted rungs, top-mounted rungs, and wall-rack-style trays for light-duty and heavy-duty applications, features rungs arc-welded to the center rail in four places, precluding, notes the manufacturer, the possibility of vibration and the subsequent noise. The center rail provides a 1.375-inch slot on the bottom and/or top for strut accessories or for support at intermediate points from the top rail. Slotted braces and brackets for adjustable horizontal and vertical couplings keep field cutting to a minimum. T.J. Cope, Inc.’s Centipede features ready-to-install pre-assembled sections with low-profile rail offering an infinitely adjustable strut track and D-shaped rungs. The company notes that the rungs, which are attached via Cope’s proprietary “swaging” process for maximum rigidity, can be easily re-positioned, added, or removed for customized layouts or load requirements. The strut track accepts strut nut attachments at any point, not just at splices. The supporting tier rail offers a bottom-strut profile for underside attachments. Wire mesh baskets Easy-to-install and generous hosts to late additions, wire mesh baskets provide an ample view of the wires they hold. They are popular options for voice/data wiring. Because they can be field cut and configured, they can accommodate rises and drops necessary to avoid various obstacles in the job path. The installer need only cut out side mesh sections and bend the necessary vertical riser or drop. As the baskets are generally wide and relatively shallow, they can hold quantities of wire without excess weight on any individual wire and therefore provide growth opportunities. The open mesh design makes cable drop-in and drop-out a straightforward process. To avoid injury to installers’ hands and possible damage to cable from any sharp edges during laying in, look for rounded or safety edges along the top framing of the baskets. Cooper B-Line Wire Basket Cable Support System features round-end technology, and high-strength steel wires. The system, made of lightweight material, allows for easy field cutting, bending, assembly, and convenient cable dropouts. In addition to the standard wire basket runway, Snap Mount wire baskets and side-angle wire baskets (designed for use with existing structural shapes, columns, beams, purlins, and angles) are available. The company’s new Rail Risers for wire basket systems provide expansion capabilities for existing systems. Shaped like an upside-down, right-angled U with two spring wires bent into retaining clips at the ends, the product snaps right onto the edging of the wire basket at recommended intervals, increasing the loading depth by 2 inches wherever needed. Cablofil Inc.’s EZ Tray steel wire cable tray, sporting a lightweight design and a “T” weld safety edge that eliminates sharp edges, features EDRN Fast Splice for splicing together trays up to 18 inches wide with only two splices and up to 24 inches wide with three splices. (An assembly tool comes with each bag of splices.) In addition to the options of using standard support systems, EZ Tray may be installed using Cablofil’s Fast Assembly System (FAS), which features profiles and brackets with special anchoring tabs that bend and lock the tray into place. Underfloor support accessories with FAS are also available. A plastic FAS Roller that snaps directly onto any tray or bolts into position allows installers to pull cables around bends, over beams, or under floors without pinching or causing cable drag. GS Metals’ Flextray Cable Management System is a lightweight wire-basket style cable tray featuring a variety of accessories designed to speed and ease cable installation. A CLEANSHEAR cutter, for example, allows installers to cut the wires for bending (with a CLEANSHEAR bender) into any preferred radius and achieve a finished edge with a galvanic protective layer of zinc that helps prevent oxidation. For connections, electricians can use either FLEXMATE connectors, which are installed with a crimping tool, or HELIFLEX connectors, which twist around wires at splice points. The system, which is available in a wide variety of colors to match its environment and a special black e-coat at no extra charge, also features toolless connectors to hold FLEXTRAY to mounting surfaces, as hold downs with center hangers, or for use with “L” brackets. Ceiling rod anchors that allow easy installation of threaded rod to wood, steel, or concrete ceilings are available and can be installed with a Flextray Extension Pole, eliminating need for scaffolding or other lifts. GS Metals also makes brackets for installation of FLEXTRAY under computer floors. T.J. Cope, Inc. offers CAT-TRAY, a welded wire mesh cable management system made of high-strength steel wires. The system offers self-splicing in straight lengths and is designed to minimize hardware requirements for supporting the tray by use of self-locking tabs on the hangers, support brackets, barrier strips, drop-outs, and other items. The line, which is compatible with new or existing strut support framework, is available in up to nine widths. Chalfant Cable Trays’ wire mesh VersaTray features snap-on splice plates to join straight sections and field-fabricated fittings, which are accomplished with a standard bolt cutter and a wrench. The line is lightweight with a high strength-to-weight ratio and well suited to indoor applications, according to the manufacturer. The line is available in seven standard widths from two to 24 inches with a 3-inch loading depth. The 6- to 24-inch-wide trays use double wires for greater load strength with less deflection. MPHusky Techtray features a tight 2-inch by 2-inch grid pattern. Compared to the typical 2- by 4-inch grid, the tighter grid could, notes the manufacturer, eliminate the possibility of small cables sagging between support surfaces and possible bruising of delicate cables. The line, available in widths from 2 to 24 inches with depths of 1 to 6 inches, features corner connectors that minimize field cutting and can be used on 90-degree turns, tees, or crosses. Fittings can also be field fabricated by cutting wires and using clips to hold segments together. Techtray can also be used under raised floors with snap-in raised floor supports. Mono-Systems, Inc., Mono-Mesh basket tray comes in 2-inch depths in several widths ranging from 3 to 17 inches. The tray is made from a welded wire grid, delivered to the job in straight lengths, and then cut to fit the layout. The system, which does not require pre-formed fittings and features various couplings, fittings, and other hardware to accommodate application needs, includes a patented drop-out system that requires no additional hardware. Easy to install, it maintains a 2-inch minimum bend radius. Other cable support systems A variety of wide base supports, including J-hooks and various types of cradle supports, can be installed at intervals that provide support within the industry-recommended 12-inch sag criterion for supporting cables from the telecommunications closet to the work area served and to help prevent cable crimping and snagging. The hooks, for example, should be spaced between 48 and 60 inches, as required by the TIA 569. ERICO, Inc., CADDY Division (the fastening division of ERICO) CatTrax continuous cable support offers flexible lightweight support for low-voltage/high-performance cable. The system includes steel support hangers designed for 3/8-inch threaded rod, a 25-foot roll of flexible plenum-rated plastic mesh, and steel snap-on connecting clips, packaged in an easy-to-tote carton. Capable of holding approximately 800 unshielded twisted pair (UTP) four-pair cables above suspended ceiling structures, the system, which is compliant with ANSI/EIA/TIA structured cabling systems standards, is among the fastest around for changing planes and directions. The system accommodates corners or elevation changes with transition pieces that bend easily for corners and placement in tight spaces. After installers place cable in the mesh, the support is secured with a steel retaining strap, which is removable, as needed, for future additions of cables, explained Larry Fisher, division manager at CADDY, further saving on labor. “We recommend using mesh in renovation and remodeling work, where there are a lot of existing items like duct work, conduit, or trays that an installer will need to weave around. Plus, you can work above existing drop ceilings without having to tear down the ceiling grid to make room to get a conventional tray into place.” Other ERICO Caddy supports include CableCat J-Hooks and other bundle supports that can be attached to various structures, including the wall, a beam flange, a vertical flange, a drop wire, or an acoustical tee. The “original” CableCat J-Hooks have been expanded to include up to 4-inch diameter loops and route cables with a sufficient bend radius to prevent pressure on those cables. The company also makes small bundle J-hooks, equipped with bend-back tab to provide containment without pressure on cables, and flexible cable wrap for large bundle supports. HILTI X-ECH and ECH Cable Holders can accept cables of various diameters, replacement cables or new cables any time. Requiring no pre-drilling, they can be installed on a variety of surfaces with either anchors or with the Hilti DX fastening system that shoots a prefitted nail into steel or concrete. Use of an optional modular pole tool attached to the DX A40 ECH and is meant to eliminate the need for a ladder for heights up to 15 foot. The ECH version of the cable holder is identical to the X-ECH version except it omits the DX pin and uses Kwik-Con or other screws for fastening. The UL-tested plenum-rated holders come in three sizes. Designed for 100-pound loads and offering capacity for up to 50 Category 5 cables, the large X-ECH-L/ECH-L cable holders feature self-locking closure and an offset shape for easy accessibility and self-regulating cable positioning. The small and medium X-ECH-S and X-ECH-M cable holders, designed for up to 40-pound weight, are suitable for holding 10 to 15 cables (3/8-inch diameter) and 20 to 25 cables (3/8-inch diameter), respectively. Cable holders interlock (small to small and small to medium, only) for expansion. Side trap doors open inward for cable insertion. The Hook, by Mono-Systems, Inc., is shaped somewhat like a capital “G” without the finishing horizontal line. The hooks, available in four different sizes, come with pre-drilled holes around the perimeter for mounting on ceiling or wall or to service as an attachment point for a metal rod. The universal holes also allow other hardware (such as wire ties) to be attached. The Hook could be particularly handy in congested areas or in spaces too small for cable tray, the manufacturer said. Cooper B-Line Cable Hook System is designed to maximize cable-bearing surface and eliminate stress. Available in three sizes, the hooks will accommodate most support applications for beam flanges, purlin, threaded rod, t-bar, ATR and under-floor support posts. Other assemblies include multi-tiered wall-mount and rod-supported dual-sided systems, which come shipped fully assembled. An optional metal Qwik-Latch cable retainer is available for use in plenum areas in place of expensive plenum-rated plastic cable ties. Suitable for installation wall or ceiling mounting or mounting below an access floor, the innovative, patented CMS Snake Tray side-loading Snake Tray features UL-approved, 8-foot lengths of bendable metal support system, which have bent rungs attached at 4-inch intervals and an attachment point at the top of the tray. The attachment hardware is inherent in the product design. According to the company, any two trays can be connected in 15 seconds. Facilitating on-the-spot directional changes without any tools or cutting of any component, the snakelike backbone may be hand-bent in any direction in 10 seconds without fear of kinking or deforming the steel, notes the company, and can handle hundreds of different bends, as required. The company’s similarly pliable Lo-Snake is designed to lie directly on the floor under raised floors, with anchoring typically every 4 feet. Capable of four directional bends, it can, points out the manufacturer, navigate over and around existing obstructions. CMS also offers Snake Canyon, fixed wire baskets (featuring a 44/5-inch grid) that are installed by laying them in between the raised floor pedestals before the floor panels are placed on the pedestals. Hard copy guide available Cooper B-Line, Chalfant Cable Trays, GS Metals, MPHusky, P-W Industries, Inc., Thomas & Betts, TJ Cope, Inc., and The Wiremold Company are all active members of NEMA section 5VE, metallic cable trays, and members of the Cable Tray Institute (CTI). A NEMA VE2 installation guide on metallic cable tray is available through NEMA, CTI, or any of their member manufacturers. The FELDMANS provide Web content and write for magazines, trade associations, building product manufacturers, and other companies. They can be reached at wfeldman@worldnet.att.net or at (914) 238-6272.

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