Practical Considerations for Telecommunications Spaces

Information processing equipment has become a ubiquitous feature in almost every building. The widespread reliance of workgroups on local networks and the Internet has placed demands on buildings to house servers and network switches, and to efficiently distribute cables to work areas.

The central themes in planning for IT spaces accommodates the inevitable future advances in IT equipment. Whereas electrical equipment typically has a service life of 20 years or more, IT equipment may be completely obsolete after only three to five years.

How then can one allocate space for such rapidly evolving systems? Building design teams often now include an information transport system (ITS) consultant. Unfortunately, all too often, the ITS consultant is an afterthought, brought into the project well into the design phase, making it extremely difficult to incorporate necessary changes to building floor plans.

An organization that has played a leading role in developing and disseminating ITS design criteria is BICSI. BICSI promotes competency in ITS design professionals through its testing and certification programs. An ITS design professional with the RCDD certification has passed a rigorous test in telecommunications distribution design practices and is required to participate in continuing education programs. One of the premier sources of design criteria for IT spaces is the BICSI TDDM, or Telecommunications Distribution Design Manual.

Telecom service entrance

The most logical place to start is at the building’s telecom service entrance. The various types of services the building will require—voice, ISDN, DSL, CATV, satellite—should be identified early on, along with the types of media necessary for these services: copper, optical fiber or coax. Another consideration is whether one or more service providers will be involved. A demarcation point must be defined for each service provider—the point where the pathways constructed by the service provider transitions into the pathways installed by the building contractor (normally at the property line).

Entrance conduits should be standardized on the 4-in. trade size. The 2-in. conduits may alternately be used for smaller buildings. Multiple innerducts should be placed in 4-in. conduits that contain fiber optic cables. The number of conduits required will vary based on building size, function and number of services required. However, it is highly recommended to provide at least one, if not several, spare conduits. These conduits are used for future growth as well as maintenance and repair operations.

If the building will house multiple tenants, the terminating space for cables should not belocated within any one tenant’s area. Also consider subdividing the space for tenants with unique service requirements.

The room should be safe, clean and well lit. Avoid locations through which piping and ductwork pass. Plywood backboards should be provided to mount entrance protectors, terminations, cable management and provider’s equipment.

Cross connection and backbone

Typically, the entrance facility also serves as the main cross connect for the building, where the building’s backbone cabling interconnects with the service provider’s cabling. Therefore this location should be selected in order to distribute the backbone cables throughout the building. Many cables need to exit this space both horizontally and vertically.

Keep in mind that in a campus scenario, the equipment space may be a shared resource for several buildings on campus. If this is the case, access to the campus backbone distribution system must also be within easy reach of the equipment room. The design of medium to large equipment rooms requires a great deal of attention to issues such as fire protection, security, UPS power distribution, environmental control and other issues.

Telecommunications rooms

How many telecommunications rooms are needed on each floor of a typical building, and what size should they be? This issue has impact on the development of floor plans and must be addressed as soon as possible. Once the number and sizes of the telecommunications rooms are determined, the next logical question is how many and what size riser conduits should be provided to deliver the backbone cables to the telecommunications rooms.

Inside the telecommunications room the cables typically terminate on one side of a cross connect. The backbone cables originating in the building’s main cross connect will terminate on another side. The interconnection of the work area cables, network switching equipment and backbone cabling occurs by inserting short patch cords to establish the desired links, which does not disrupt backbone service.

Standard practice is to limit cable length from the telecommunications room to the work area to 295 ft. If work areas farther away than this are required, additional rooms or a smaller enclosure should be provided to serve these areas. The telecommunications room should be placed in a central location that is reached by the backbone riser conduits. For this reason, stacked telecommunications rooms on each floor are highly recommended: Stacked telecommunicaions rooms also provide a vertical pathway with easy access to backbone cables.

Of more concern is planning for the ease of installing and modifying horizontal cabling out to the work areas. There are many choices when it comes to pathways for horizontal cables to the work areas. Overhead trays or conduits, infloor or raised floor distribution, and surface raceways that also serve 110 volts AC power are among the most common. Generally the more flexible systems are in terms of ease of facilitating moves, adds and changes, the more expensive they become.

Trends

One of the recent trends in ITS design is to integrate cabling and pathways for a variety of systems into the voice/data infrastructure. An inflexible system that is difficult to administer often requires new cabling to accommodate system changes.

Internet Protocol (IP) based equipment and “open protocol” HVAC controls are becoming more prevalent in modern buildings. When these devices are combined with a structured cabling approach, a number of significant advantages are achieved. A few of these are:

• A single source of responsibility for the design and installation of cabling and pathways

• Reduced engineering time through reduced repetition of cabling and pathway design

• Reduced construction labor time through reduced repetition of installed cables and pathways

• Flexibility to incorporate future moves, adds, and changes

• Standardized cabling and pathway identification system

• A single database to manage the entire cabling and pathway system.

There are dozens of other issues that need to be addressed in the design of telecommunications spaces and pathways. However, these issues can betackled in the later stages of design development, after the requirements for building space have been identified.

Hopefully the above discussion has provided a basic familiarity with telecommunications rooms, and also with a few of the issues that must be addressed when a new building is in the early design development stages. As information processing becomes an ever larger component of today’s work environment, the requirements of IT infrastructure must be closely evaluated and integrated into the overall building.

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