Imperative Infrastructure

Voice-, data- and video-transmission systems have quickly become a necessary feature of school and office design

By Jeffrey Lupinacci, RCDD, Brinjac Engineering, Harrisburg, Pa. May 1, 2001

In today’s school and office environments, communications services have become indispensable “utilities.” These systems are essential to daily operations, and building occupants demand high availability from their voice, data and video (VDV) networks.

With telecommunications more than with other utilities, the rate of growth in the number and the speed of connections has been astronomical—and it shows no sign of slowing. This not only causes telecommunications engineers and designers to carefully review all the requirements for a client’s space, but also to plan for future contingencies.

Traditional telecommunications systems and cabling infrastructures were developed for relatively low-speed data rates by “Ma Bell” employees, in a secret method known only to those with access to the Bellcore standards. Over the past 20 years, with the explosive growth of the computer industry—local-area network/wide-area network (LAN/WAN) industry, cable television and satellite industries—systems are dealing with millions of times more data.

Not only data rates have increased. With greatly reduced hardware and software costs, most office workers and students now have computers, adding millions of communications users and contributors.

So what can be done to support this growth? Designers and engineers must create an infrastructure that can support all the required VDV-cable distribution and equipment. Infrastructure designs may be for a renovation project or a new building, and each has some differences. New buildings are much easier to lay out with the latest components, but if adequate time is spent, a retrofit can also be successful.

The most critical items to address are budgets, services, spaces and pathways. When these factors are included in the planning and design, a building can experience various changes to VDV distribution without major reconstruction. Stranded investments

All services, systems, spaces and pathways have cost implications for the total budget. When developing the scope of work with a client, it is important to have a budget—and a feel for what is important to them. Many clients expect to be out of a building in a few years, and don’t want to leave their building investment stranded. Some may be using a specific system today but have expectations of migrating to a different system in the near future, preferring not to invest in more equipment.

The amount of the project budget devoted to VDV systems can often change or be replaced over the next 10 years, but the budget dollars that are invested in pathways and spaces tend to remain fixed for 20 years or more.

The best way to design these systems is to start by working hard to get the appropriate budget relative to the critical nature of the system. It takes effort to educate the client and to protect their interests from the tug-of-war between competing project priorities. Once a budget is established, it’s best to invest in the things that last the longest and provide maximum return on investment: spaces, pathways and backbones.

Each system has unique requirements for installation and maintenance, but together they are critical to a school’s or an office’s requirements. All designs should meet or exceed the requirements of American National Standards Institute/Telecommunications Industry Association/Electronic Industries Alliance (ANSI/TIA/EIA) standard 568-A-5, Commercial Building Telecommunications Cabling Standard with Addendums 1-5 and ANSI/TIA/EIA standard 568-B-3, Commercial Building Standard for Telecommunications Pathways and Spaces , 1998.

The selection of communications media and equipment should depend on the people using and maintaining the systems once they are installed. If there is a skilled group of technicians, a more sophisticated system can be installed. The less skilled the staff, the more “plug-and-play” the design choices should be.

Different environments have unique requirements and concerns. For example, if the client is a school on a campus, they can save on the recurring costs of leased data circuits between sites and the Internet by installing interbuilding backbone cabling. To tie the buildings together, a designer can run cables aerially on poles, in duct banks or even through a tunnel. The easier it is to add cables in the future, the less there needs to be installed today.

When designing for a high-rise office building, placing the equipment room in the core of the

building can minimize backbone length. Another idea that the designer may want to consider is placing tie cables between adjacent floors, in addition to the collapsed backbone, making it easier to connect departmental LANs.

As users live with their new system over years, “churn rate”—the amount of original installation that needs to be altered, removed or reinstalled over the course of a year—comes into play. Churn rate is different for all clients: Schools and apartments are a lot lower than corporate, university or hospital clients, which often exceed 30-percent churn. The more flexible the system—and if the backbone, spaces and pathways are designed properly—the lower the labor costs for users of the system. Rooms and closets

Spaces are critical in infrastructure design for cable-termination and equipment-housing needs. Standards exist that provide design guidelines as well as code requirements. In the United States, the standard to follow is ANSI/TIA/EIA-569-A-4, Commercial Building Standard for Telecommunications Pathways and Spaces , March 2000. This standard defines the minimums for pathways and spaces based on current technology and planning for the future.

One such space is the equipment room —or computer room . This is considered a building-serving space where all the main equipment is housed. Adequate equipment-room space should be established with the following requirements:

  • The room should be created on core walls that have room for expansion, and located away from elevators, high-voltage switchgear, water piping and exterior window walls.

  • Low-hanging vertical obstacles—vents, sprinkler heads and light fixtures—should not hang lower than 8 feet from the floor, as they may get in the way of service or installation requirements.

  • The environment should be conditioned at 64°F to 75°F, with 30- to 35-percent relative humidity on an uninterruptible, 24-hour schedule.

  • The room should be accessed from a main corridor, with a sturdy and lockable 36-inch by 80-inch door—without a threshold—that physically protects the equipment.

  • The light for terminations should be 50 footcandles at the termination point.

  • Power to the room should be provided on a transient-voltage surge-suppression panel from an uninterruptible-power supply source with generator backup.

  • If no generator is available, a minimum of two hours battery life at full load must be provided in order to have adequate time to softly shut down applications and equipment.

  • The space needed for cable backbone termination and devices in equipment rooms should be as shown in Table 1.

Additional space is needed to house local equipment and further distribute VDV signals to the work-area outlets (WAOs). Each floor should have a minimum of one telecommunications (TC) closet or, for large floors, TC closets should be located so that all WAOs can be reached within the 295-foot cabling distance requirements. To provide the appropriate environment for floor-serving components to the VDV-distribution system, the environmental conditioning for a TC closet should be the same as an equipment room. Table 2 on page 60 offers some size requirements, as outlined by the ANSI/TIA/EIA standard 569A. A great design always features stacked TC closets to minimize the pathways, backbone-cabling distances and construction costs. Highways and byways

Pathways are like highways that connect communications spaces. Usually, the greater the cost for the pathway, the greater capacity and flexibility there are for changes to the system in the future.

Communications pathways actually begin outside the school or office, bringing services into the facility. In a campus environment, the end-user may own the pathways between buildings; these must also be designed to support the cables with adequate capacity for future. Options for these entrance facilities or campus pathways include aerial, direct-bury, duct-bank or tunnel distribution. Oftentimes, different service providers want dedicated pathways into the main point of presence for the building or campus; distribution from that point on is the responsibility of the owner.

A good plan for these outdoor pathways is to install a 4-inch conduit for service coming in and 100-percent additional space for the future. The cost of the excavation, concrete and road repair is the most expensive part; additional ducts are relatively cheap.

The pathway for connections between the equipment room and each TC closet depends on the amount of cable being run, but a minimum should be three 4-inch conduits to each, and two 4-inch conduits between TC closets on the same floor. No conduit segment should have more than 180° of bends or go 100 feet without a pull box. Sleeves and slots can be used to penetrate floors or walls for large quantities of cables.

Other methods to distribute VDV cables vary based on the space. Cable tray is a great method for distributing large quantities of cables and adding cables with ease, but the cost of cable tray might require that it be placed only where the concentration of cables is heaviest.

Surface-mounted raceway is a great product for retrofits—and for flexibility—but the cost can add up quickly and it is important to specify it with all the corners and fittings for a complete system.

Underfloor duct and cellular systems create a flexible pathway for future growth and the changes of modular office designs. But the truth is, these systems usually aren’t designed with adequate capacity for increasing data communications, and are quite costly to install. They are definitely not for use in a retrofit project.

More flexible—as to the direction the cabling can run—are “J” hooks and cable slings through the open ceiling or under the raised floor. These solutions are also relatively inexpensive. But it is important to install them every four to five feet to support the cables and not create sags in the cable runs. These can feed into power poles, poke-throughs or modular furniture for the final run to the WAO. Bringing it to the user

WAOs are the point of the system that the end-user sees; therefore they should be attractive and easy to use. Most manufacturers provide color-coding and labeling space to assist end-users in selecting the correct place to plug things in. It is recommended that the designer specify, or at least approve, the labeling plan for a complete cabling system. It is possible to provide VDV connectivity with a faceplate containing three 8-pin modular jacks; without the correct labels the user could damage expensive equipment by plugging into the wrong outlet. All labeling should be specified to meet the requirements for ANSI/TIA/EIA standard 606, The Administration Standard for the Telecommunications Infrastructure of Commercial Building , February 1993.

A double-gang workbox should be used for all communications WAO to allow for slack storage and bend radii behind the faceplate. A “mud ring” or reducer can be used to allow attachment of a single-gang faceplate.

A minimum of 1-inch conduit should be used for all stub-ups or conduit runs, and the designer should never exceed 40-percent fill in conduit, as specified by the National Electrical Code, and bend radii should not be tighter than 20 times the inside diameter. Managing risks

The idea that communications services have become indispensable utilities in today’s school and office environments is evident whenever these services break.

As we move further into the information age and toward telecommuting, the importance of stable VDV systems will be critical. The more money that can be lost if a system fails, the greater the justification is to increase the expenditures for keeping these utilities running. No longer can owners get all their design services, installation, testing and certification from a contractor who may be operating from a van or garage—and just happens to be the lowest bidder.

The risk is too great and the systems are more specialized than ever before, making engineers and designers of these systems even more valuable to the architect and owner.

Table 1 – Equipment Termination Space

Floor Space Served (ft2) Closet Size (ft) Wall Length (ft)
From ANSI/TIA/EIA standard 569A
100,000 12 x 6.5 39
200,000 12 x 9.0 42
400,000 12 x 13.0 68
500,000 12 x 15.5 90
600,000 12 x 18.5 96
800,000 12 x 22.5 120
1,000,000 12 x 27.5 144

Table 2 – TC Closet Size

Serving Area (ft2) Closet Size (ft)
From ANSI/TIA/EIA standard 569A
10,000 10 x 11
8,000 10 x 9
5,000 10 x 7

A Quick VDV Review

The basic types of voice, data and video services and systems for today’s typical schools or offices all require space, power, HVAC and cabling-support systems. The services and systems that need to be planned for include the following:

Voice. These systems include private branch exchanges (PBXs), voice-mail systems, key telephone systems, interactive voice-response units, predictive dialing systems, channel banks and associated power supplies.
Voice distribution consists mostly of unshielded twisted pair (UTP) copper—category 3 or better—but fiber-optic cable (usually single mode) is very common for multiplexed trunking or remote shelves.

Data. These components include routers, modems, switches, servers, testing equipment and associated power supplies.
Data distribution consists of high quality UTP copper—enhanced category 5 or better—fiber optics, both single mode and multimode, and any legacy networks connected with coaxial, twin-axial or shielded twisted pair (STP) or STP copper.

Video. In this category are media-retrieval systems, content-delivery systems, satellite receivers, cable-television amplifiers, video sources such as DVD players or VCRs, video servers and associated power supplies.
Video distribution can be accomplished over UTP, STP, fiber-optic or coaxial cabling. Each distribution method has its benefits, but usually only one media type is used. The most cost effective—while providing a very high bandwidth—is still RG-6 coaxial cable with “F” connectors.

A Division All Its Own

The uniqueness of design and the critical nature of voice, data and video (VDV) systems has created a push toward the segregation of VDV, security and sound systems into a separate division under the Construction Specification Institute’s MasterFormat.

Bringing these services out from under the umbrella of the electrical contractor and Division 16—creating the new Division 17—is expected to allow more direct input from telecommunications professionals and thus, it is hoped, a better control of the desired outcome. With prime Division 17 contractors that understand the bend-radius issue of pathway placement, the quality of the systems installed will likely be of a higher caliber. As prime contractors—rather than a subcontractor to an electrical contractor—they should get a seat at the job conference table to ensure that the corresponding heating, ventilation, air-conditioning, power and lighting issues are not ignored.

This separation has been a topic for discussion in publications by the American Institute of Architects, the Association for Telecommunications Professionals in Higher Education and other engineering, electrical and telecommunications publications.

A good place to find out more about Division 17 is at