Hybrid fiber-optic cable gets high marks on campus

April 1, 1997
When this leading college overhauled its network, it used hybrid singlemode/multimode optical fiber to meet current multimedia needs and allow for future network expansion.

When this leading college overhauled its network, it used hybrid singlemode/multimode optical fiber to meet current multimedia needs and allow for future network expansion.

Tom Debiec and Melynda Wagner, Berk-Tek

In the spring of 1993, Elizabethtown College identified the need to upgrade its wiring and data-management infrastructure to handle the ever-increasing information explosion. The college was taking on a task that would require three years to complete.

Elizabethtown College, a leading liberal arts college, is located on 185 wooded acres in Elizabethtown, PA. The college includes 44 buildings, both on and off campus. Eight academic buildings are located within 1000 feet of each other. There are 7 dormitories with a total of 616 rooms and a 32-unit townhouse to accommodate additional students.

The existing infrastructure consisted of a hodgepodge of network configurations, and only three academic buildings were connected to the network. Student access was limited to data terminals located in these buildings.

One of the driving forces for evaluating the telecommunications system was the need to provide video in the dormitories for educational and entertainment purposes. For example, communications majors who produced community-access television and radio programming were not able to view their work and receive feedback from viewers and listeners. Additionally, the college needed to address other issues, including energy-management and data-communications capabilities for students and faculty.

In early 1993, the college contracted with a Harrisburg, PA-based consulting firm to conduct a site analysis and provide recommendations for recabling. This survey identified numerous areas in the existing cabling infrastructure that needed improvement, including

- numerous low-voltage splices that were subject to immersion in water,

- conduits filled with abandoned cables,

- inadequate transient voltage surge suppression,

- inadequate grounding connections,

- very narrow maintenance holes,

- cables located in maintenance holes that were inadequately supported.

In addition, the existing telephone system, even though recently installed, was inadequate to support the college`s requirements. Inside wiring used 2-pair wiring rather than the industry-standard 4-pair. There were no dedicated telecommunications closets in any of the buildings, and the wiring was not terminated in compliance with the standard of the Telecommunications Industry Association (TIA--Arlington, VA).

Based on the recommendations made in the engineering survey, the college developed a plan that not only solved existing problems but also created a cabling system that offered flexibility and growth potential. Commonwealth Communications Inc. (CCI--Wilkes-Barre, PA), a full-service engineering, systems, and technical services firm specializing in cabling installation and management, was contracted to design and install an effective network cabling system for the college.

The telecommunications cabling strategy was based on the current tia/eia-568a commercial building telecommunications cabling standard. According to the engineering study contracted by Elizabethtown College, this standard was chosen because components compliant with it are readily available from a variety of manufacturers.

Fiber wins out

The backbone, entrance facilities, and horizontal wiring were among the cabling systems that needed to be upgraded to support future data, voice, video, and energy-management demands. Choosing the right medium for the backbone cabling was a primary concern, and the college came to recognize the long-term advantages of installing fiber-optic cable because of its high bandwidth, low attenuation, and electromagnetic immunity.

The choice was a simple one, according to John Marisic, director of computing at Elizabethtown College. He comments, "Since we were overhauling our entire cabling infrastructure, instead of doing it using the patchwork method, it made better economic sense to install fiber-optic cable now to support our current needs for high bandwidth, such as the video we are running at our campus TV station, as well as to plan for the demands on our system in the future."

The college chose to install fiber-optic cable manufactured by Berk-Tek in a hybrid construction consisting of 30 strands of 62.5/125-micron multimode fiber and 6 strands of singlemode fiber. In addition, a 6-multimode/4-singlemode composite-fiber cable was used for 12 off-campus houses. These cables were installed as the backbone between buildings, with the multimode fiber used to transport data across the network and the singlemode fiber used for the video-distribution requirements of the community-access and cable TV on campus.

Marisic says hybrid fiber-optic cable was installed between buildings because the hybrid construction meets the physical-layer needs for the present as well as the future and provides for the seamless transfer of information across the network, regardless of the changes that may occur in the application, presentation, or session layers.

One of the college`s major concerns was to lessen the damaging effects of frequent power outages caused by lightning strikes. Also, there were electronic problems due to the operation of a turbomodulator located near the computer center in Nicarry Hall. This history of electrical disturbances was another reason for selecting fiber-optic cable as the campus backbone: It is immune to electrical noise, magnetic fields, and voltage transients.

Project delays

When CCI began to work at the site, there were delays that could have turned out to be a project manager`s nightmare. The blizzards of 1996 dumped 30 inches of snow on the campus, preventing any outside work until the spring thaw. This delay actually worked to CCI`s advantage, however, because the snow insulated the ground and prevented a hard freeze. This permitted the company to begin excavation for new conduit earlier than anticipated, and the project manager for CCI, Ross Thompson, and his crew were able to start rewiring for the new system ahead of schedule. According to Thompson, "There was plenty of work that needed to be completed within the campus facilities themselves, so as the weather turned blustery, we had no hesitation about working inside, where we laid the foundation of the internal network-cabling system."

During the summer months, CCI planned to cable all the dormitories, but it turned out to be the busiest conference season ever, which meant that the dormitories were occupied throughout the summer. For both the college and CCI it became a logistical concern. Nevertheless, good communication and coordination with the college staff allowed Thompson and his crew to start rewiring for the new system. "Due to the close cooperation with Elizabethtown College`s plant operations, conference services, and network services, the project was completed as scheduled and everyone involved considered it a success," says Thompson.

More than 1.1 million feet of Berk-Tek Hyper+Plus Category 5 cable was installed to support 2400 workstations. Four wallplate configurations were specified for the installation, depending on application. Dormitory rooms were wired with four Category 5 cables (two voice and two data) and two RG-6 coaxial cables for cable-TV access, depending on the number of students residing in each dorm room. This set-up allowed each student to have direct Internet access from his or her own computer, as well as a private telephone line. Also, the fiber-optic cable installed was able to support the campus power supply, which allowed for regulation of heating and air conditioning throughout the campus.

According to Rick Evans, Elizabethtown College associate director of academic computing, "A primary motivation for installing optical fiber was so we would stay competitive in Internet access and distance-learning. As the fourth-ranked liberal arts college in the Northern Region, we need to have a competitive edge over other universities in order to attract top students. Students demand the Internet for such things as doing their research, online buying, and e-mail correspondence."

Across the campus, 15 classrooms were designated as multimedia "smart" classrooms. These classrooms were supplied with one Category 5 outlet for data, one Category 5 outlet for voice, two multimode fiber-optic cable connections, two singlemode fiber-optic cable connections, and one RG-6 coaxial-cable connection. This configuration was also used in main lecture halls, recital halls, and several theaters around the campus. In anticipation of demand for high-quality graphic and visual imaging requirements by the chemistry and biology departments, the college also decided to install fiber-to-the-desk in its facilities. This configuration permits direct connection to the campus video system via singlemode fiber-optic cable, which in turn allows for high-speed data connections.

Five new maintenance holes and approximately 2 miles of conduit were installed to tie in the north side of the campus. To connect all 44 buildings and houses, approximately 60,000 feet of hybrid fiber-optic cable was installed.

When the college installed this wiring infrastructure, hybrid fiber-optic cables combining multimode and singlemode fibers under the same cable jacket were special-ordered from Berk-Tek through Graybar Electric Co. (Allentown, PA). However, the company now manufactures these cables in gel-filled outside-plant and tight-buffer indoor/outdoor designs in a number of fiber counts and combinations.

Click here to enlarge image

Rick Ladd (left), project supervisor, and Ross Thompson (right), project manager, work for Commonwealth Communications Inc. (Wilkes-Barre, PA), the cabling contractor responsible for upgrading the Elizabethtown College cabling plant. Here they check wiring in one of the college`s telecommunications closets.

Click here to enlarge image

Hybrid fiber-optic cable may be either tight-buffer or loose-tube. The tight-buffer construction depends on the cable jacket and fiber buffering to keep moisture away from the optical fibers (a). In a loose-tube construction, the fibers are contained loosely within tubes packed with moisture-resistant gel (b).

Click here to enlarge image
Click here to enlarge image

Tom Debiec, registered communications distribution designer (rcdd), is an applications engineer, and Melynda Wagner is marketing communications manager, both at Berk-Tek (New Holland, PA).

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