Flexible Wire and Cable Management in Renovated Buildings
Poke-Thru Devices Maintain Slab Fire Rating

Few things age faster than a building with an inadequate wiring and communications cabling infrastructure. A building may be structurally sound in every way, but if the wiring and cabling is outdated or inaccessible, the flexibility -- and hence the value -- of the space is sharply reduced. This is particularly true of open-landscape buildings or traditional-plan facilities that are being converted to open plan.

Yet the demand for flexible space is rising dramatically. To meet this demand, a growing number of owners and developers have come to recognize the value in renovating existing buildings. A key to taking advantage of the savings inherent in renovation versus new construction is to economically upgrade the wiring and cabling infrastructure to provide the flexibility that is vital in today’s work environment. Fortunately, there are wire management solutions that can create flexibility in open spaces, even in older buildings.

Poke-thru devices are among the most versatile fittings for renovation and retrofit of electrical and structured cabling systems. Poke-thru devices enable wiring and cabling to be located virtually anywhere on the floor plan using core-drilled slab openings. Today’s advanced poke-thru devices offer significant flexibility without sacrificing safety since they maintain the fire rating of the slab.

Fire Safety

Prior to the development of the newest generation of fire-rated poke-thru devices, core drilling of concrete floors required installation of fire stopping material to maintain the floor’s fire retardant capabilities. Unfortunately, these operations could not always be adequately policed, and code enforcement agencies moved to limit the practice. The solution was to incorporate fire stopping material into the fitting itself, guaranteeing that each penetration maintains the slab’s fire rating.

The key to a poke-thru serving as a fire stop is one or more rings of intumescent material and phenolic spacers around the conduit stem at the slab level. When exposed to high temperatures, the intumescent material expands to fill any space between the fitting and the floor slab. In the event of a fire, the slab penetration is quickly filled by the expanding intumescent material, effectively blocking flames and heat and maintaining the slab’s fire rating.

Communications Cabling

Manufacturers of poke-thru devices have responded to the growth and increased complexity of structured cabling systems by developing specialized fittings for Category 5 cabling. These devices feature separate channels for electrical wiring and low-voltage cabling and, in some recent designs, a metallic shield that drains EMI/RFI interference through contact with the conduit system. In poke-thru devices that support both electric service and low-voltage cabling, the electric wires are run through the conduit stem of the fitting while low voltage cabling runs outside the conduit stem through holes in the intumescent rings. In the event of a fire, these holes, like the slab penetration itself, are filled by the intumescent material.

A current trend is toward high device capacity and low-profile activations. These new devices offer enhanced service, convenience, and flexibility for single or multiple workstations.

Renovation Solutions

Any existing multistory concrete slab structure is a candidate for electrical and structured cabling system renovation utilizing poke-thru devices. (Since poke-thru devices require access to wiring and cabling run in the plenum space below, they cannot be used in slab-on-grade structures.) Holes must have a minimum on-center spacing of 2 ft.; and not more than one hole is allowed per 65 square feet in each span. Thus, poke-thru density can be as great as one for each 8-ft. by 8-ft. workstation.

Numerous poke-thru profiles and activation fittings are available for electric service, dedicated communications cabling, and combinations. Service fittings fall into two general categories: raised and flush. High-capacity poke-thru devices enable multiple workstations to be fed from a single location. Flush, raised, and furniture service fittings and a variety of face plates are available to meet power and/or voice and data wiring in renovated buildings.

Poke-thru devices are not the only wire and cable management systems that are well-suited to renovation and retrofit applications. Perimeter raceways, cable tray, service poles, and even infloor ducts have been employed successfully. While these systems differ in their design and location, they share common attributes, including the flexibility to accommodate both routine changes and large-scale system expansions and replacements.

Overhead Distribution Systems

Overhead distribution systems, whether concealed in suspended ceilings or installed in open overhead spaces, offer a high degree of flexibility, both in terms of locating the components and accessing the cabling contained within them. Overhead systems include wireway and cable tray systems that are available in single-channel and divided configurations with a variety of sizes, covers, and hanging options.

Cabling from any overhead distribution system must eventually be dropped to floor-level equipment and workstations. There are a variety of ways to accomplish this. Solid bottom cable tray or wireway can be installed vertically against a wall or a suitable support column. Drop-out fittings guide the cables from cable tray or wireway into these vertical enclosures. Another option is service poles that distribute power wiring and low-voltage cabling from overhead systems to individual work spaces where the communications systems are accessed by modular jacks and other connectivity devices located on the pole.

Perimeter Raceway Systems

Another general type of wire management system is perimeter raceways that route wiring and cabling securely along the building’s walls. Perimeter raceway systems are often specified for areas that require aesthetically pleasing, easily accessed cabling systems, such as conference rooms, offices, classrooms, and training centers. Unlike conventional conduit, wire and cable remain easily accessible at all times.

Available in a variety of materials, raceways offer single or multiple channels and accept integrated communications activation devices. Perimeter systems are frequently installed in combination with overhead or infloor systems. For example, voice and data cabling may run through an infloor duct system from the communications closet to a workstation area. The cabling is then routed from the trench to surface raceways that are attached to workstation partitions, providing convenient access to the communications networks.

Infloor Distribution Systems

Although used primarily in new construction, infloor duct systems are an option for improving wire and cable flexibility in renovated structures. In typical renovation applications, channels are cut into the existing slab. After the duct system is installed the floor is finished with new concrete. Access to wiring and cabling is provided by low profile service activations in the floor.

These wire and cable management systems provide renovated facilities with both operational and systems flexibility. Operation flexibility encompasses the day-to-day or month-to-month changes required for the workplace to keep pace with the functions being performed in it. A good example of this type of flexibility is changing a conference room into a multimedia training center overnight. Systems flexibility, on the other hand, enables a facility to accommodate new or expanded communications technologies over the long term. An example of long-term flexibility is upgrading to a Category 5 or fiber optic system. Flexible wire management systems also add value to renovated buildings by lowering operational and long-term systems costs by efficiently and economically managing increasingly complex building wiring requirements.




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