A well-planned and executed structured cable management system in a building tells building managers where and how much cabling is in the structure and which cables connect; it also facilitates system maintenance and simplifies troubleshooting and repairs.
Because structured wiring often may be upgraded or moved, cables must be easily accessible and not tangled.
An efficient cable management system begins with planning and is followed by careful installation using the containment options appropriate for the requirements of each project.
A contractor’s perspective
“Basket trays are the most widely used within the ceilings of new construction and remodeling,” said Jeff Barber, vice president, systems integrator group, Valley Electrical Consolidated Inc. “Ladder racking is most common inside the equipment rooms/closets. Snake and flex trays often are used in raised-flooring areas.”
Floor ducts are very common in laboratory spaces, conference rooms and centers, training facilities and for similar uses, he said. Wiremold and surface raceways are frequently used in remodeling work where the walls are concrete block or brick. J hooks and nylon-support saddles are very common when adding to existing buildings and for shorter runs within office space and classrooms.
“They are easy to hang on ceiling supports or anchor to a wall, and they come in a variety of sizes for the number of cables needed to be supported,” Barber said.
Manufacturers of cable trays, baskets and related products continue to develop designs with components that assemble easily with tools commonly available. However, a variety of specialty tools are needed to route cables.
“Fish tapes are the most common that we see on a daily basis,” Barber said. “Lots of pull string is needed for attaching to the cabling as it is pulled through trays or conduits. For long conduit runs, we will use a pulling lubricant to ensure the cable pulls smoothly and the jacket is not scuffed or burned from the friction.”
Work is facilitated by large wire carts with the ability to set up multiple boxes or reels of wire to pull the cabling in. Barber said, for very large cable installation (e.g., 600-pair telephone cable), installers could use an electric tugger to pull the weight of the wire the longer distances between manholes and hand holes.
Fiber optic cables in structured wiring
“We are seeing more fiber installations each year going in across all types of projects,” Barber said. “With the development of more and more IP-based devices like [Internet protocol] CCTV cameras, IP alarm panels, voice over IP telephones, high-definition video, and media systems, the need for high speed and reliable bandwidth is critical in today’s communications industry.
“The days of running separate wiring infrastructures for each system are over. The systems/networks have converged to IP-based fiber and category cabling,” Barber said, adding that fiber in these systems must be handled with care.
“Always protect the fiber from being crushed or stepped on,” he said. “Always install the fiber by pulling the Kevlar cord internal to the cable so that the cable is not stretched, causing a break the fiber optic glass. Safety is also important while handling the fiber. Always wear proper PPE like safety glasses/face shield. Always dispose of scrap properly, and never eat or drink in the areas that you are working with the glass. One small piece of glass in the eye or ingested can make for a really bad day.”
Weather and temperature also must be considered in cold-weather climates.
“Cable is to be installed per the manufacturer recommended temperatures,” he said. “This is stated on the side of the reel or box. Cold weather installs can result in cracking the outer jacket of the cable.”
Finally, ensure the correct cable is selected for the installation.
“Plenum air spaces require plenum cabling and pathways to be installed,” Barber said. “We see a lot of this in the field when retrofitting buildings. Per the NEC [National Electrical Code], old, unused cable must be removed from the building.”
Manufacturers of cable containment systems have excelled in producing products that fit together quickly and easily without the need for special tools. Cable-handling equipment has seen significant recent advances to simplify the logistics of getting cable to job sites and facilitate its installation (the topic of a future Cool Tools report). Fish tapes and special cable-placement tools speed getting cables on, in and through containment structures.
“In today’s modern building scenario, cable trays are a necessary part of the infrastructure of any structured cabling solution,” said Roger Jette, president of Snake Tray. “Ease of installation, structural integrity as well as visual appearance should always be of paramount importance when designing and implementing any built component, especially now because many of the installations are in open architectural environments.”
Specific products may be chosen based on the category and volume of cables and the setting in which the pathways must pass through. In many structured cabling installations, cables pass in free airspace, allowing for the use of open architecture products, while others may require an enclosed tray, especially in harsh environments and secured network installations. The NEC also mandates the type of system used for electrical cables based on energy carried, voltage, amperage and other factors.
Cable fishing tools
There is a wide range of fishing tools for routing structured wiring, said Andy Battermann, Greenlee product manager.
“In addition to fish tapes,” he said, “reachers are extendable poles, suitable for a range of fishing applications outside of conduit; caster guns are primarily used for runs above foam ceiling tiles. Since they ‘cast’ the string, they can be used to route VDV cables above pipes, conduit and other obstacles. Flexible drill bits are primarily used in residential applications—usually when routing cables behind existing dry wall. Pulling grips can be attached to the end of these bits.
“Vacuum blowers are increasingly popular in new construction. While they can be used as a conventional shop vacuum, they also can be used when preparing for larger pulls or can be used with string to pull smaller gauge cables, such as Cat 5e Ethernet cables,” Bettermann said.
Dave Mueller, Klein Tools senior product manager, said that fish tapes are made from various materials, including steel, resin and fiberglass, with the type of job and site conditions determining the best tape to use.
“Energized work sites,” he said, “require use of nonconductive materials to prevent sparking. Long runs or heavy pulls require use of stiffer, more durable materials such as steel or fiberglass. Wide flat tips are available for running wire under flat surfaces such as carpets.”
Heavily contoured, short-distance runs require highly flexible materials such as nylon or spring steel to make the bends and turns. Plastic materials are well-suited for humid or wet environments to eliminate corrosion concerns.
“Overhead plenums and suspended ceilings are usually dark areas, so datacom installers want higher visibility fish rods and tips that illuminate the work area. These features make feeding cable more efficient and productive by avoiding obstacles and enabling quick visual location,” Mueller said.