A telecommunications system retrofit can be far more complicated than installing a new cabling system.
Planning for a retrofit installation involves a multitude of tasks that you must complete before you even begin to remove or install cable. Determined by the scope and design of the cabling installation, each retrofit requires you to address a unique set of circumstances. Some retrofits involve a simple expansion of a phone system or a data network. Others may involve voice and data systems, security and fire-alarm systems, and an upgrade to the backbone or horizontal-cabling infrastructure.
Usually, customers have already developed an idea of what they want in a retrofit. In most cases, you'll have copies of the bid, a request for proposal, formal contract, purchase order, or some other official document that conveys the customer's intentions. Most of the time, this package contains the drawings and specifications that determine the materials you must use and when and under what standards you plan to install them. The larger the project, the greater the complexity of these documents, and the greater their importance to a successful installation.
You should obtain all the available documentation on the existing installation from the customer, including the cross-connect records and any information on the proposed system. Many times, existing documentation only contains information from the initial installation and does not reflect the last 10 years of moves, adds, and changes (MACs). You should plan on spending numerous man-hours or even days verifying the existing infrastructure.
You should prepare separate drawings for each type of telecommunications system you plan to install. That is, you must prepare separate drawings for copper, optical-fiber, coaxial, and low-voltage cables. If the project is small enough, you can place all of this information on a single drawing.
Larger retrofit projects may require a series of drawings and complex project schedules. The first set of drawings should include the existing closets and infrastructure. The second set might include temporary facilities needed to free up space for the final installation, and a third set of drawings could show the final configuration.
These drawings should include elevation details of the closets and the arrangement of the various types of equipment. You should also incorporate a detail of each wall and rack in each closet, as well as a plan view of the floor-mounted hardware. The drawings must also indicate the cable supporting structure you plan on using.
Equipment and personnel installation logistics. In ideal situations, the retrofit will take place in unoccupied spaces. This allows you to remove all equipment and cables that will not be part of the new installation, so you can have a valuable pathway and closet space for the installation of new system components.
However, cabling isn't the only concern in a retrofit. In large retrofits that require extensive work-area re-cabling, it's a good idea to have temporary office spaces where personnel can relocate until you complete their section of the retrofit. We call this practice swing-floor phasing, because groups of personnel swing from one floor area to another as you phase them into service.
Another approach to swing-floor phasing is to work with the customer to develop a master plan of swapping office areas. For example, the accounting department might move into temporary trailers while you rewire the old accounting spaces. Then, the purchasing department could relocate into the old accounting spaces while you rewire the vacant purchasing department spaces. Telemarketing would then relocate into the rewired purchasing spaces, and so on, until you rewire all office spaces and the accounting department moves into the last rewired space. This form of swing-floor phasing requires the accounting department to move twice while all other departments only move once. This saves the customer time and money when preparing for the augmentation.
The augmentation of an existing installation. When determining what part of the existing cable plant you plan to reuse during the retrofit, good communication with the customer is essential. If the customer wants to utilize portions of the present cable and equipment, the existing components must conform to the new requirements. In many cases, system upgrades require a new cabling configuration that doesn't allow the use of the current infrastructure. Obtain as much information as possible from the customer and verify that the information is accurate. If the existing documentation is questionable or does not exist, it may be necessary to trace and document the current system. In addition, you must test the existing cable plant to verify the level of service it can support.
After you verify and test the infrastructure, you can determine which pathways, cables, and equipment to reuse. Then, the challenge is to incorporate the new components into the ones you plan to reuse.
If the telecommunications closet does not have adequate room for the old and new components, you should do the following:
Build additional closets.
Expand the existing closet.
Float the existing equipment and cables. In a small closet, you may need to extend the existing equipment and cables into the hallway to make room for the new system. You can remove the old system components after the cutover is complete.
Install temporary cabling. Temporary cabling is exactly what its name implies. It provides service until you complete the cutover. You then remove it.
Large office retrofits may require extensive work-area re-cabling and closet renovations. Temporary cabling can be either backbone or horizontal cables. It may be easier to temporarily relocate a small telephone system from the closet into an office and run the horizontal cables around the perimeter of the floor until you install the new system.
After you install and test the new cables and equipment, you can begin transferring to the new system. At this point, you must develop a detailed plan to cut the new components into the final working configuration. Depending on the size and scope of the retrofit, either a phased cutover or a flash cut may be necessary.
A cutover from the old to new system is one of the most detailed and critical steps in a retrofit. To help ensure a high-quality transition and to expedite the cutover, you need to use cutsheets. Cutsheets are documents that contain the existing cross-connect terminations and show the changes necessary to execute the cutover. You can also document each circuit with a Circuit Layout Record (CLR). CLRs provide a quick graphical representation of the circuit layout. They show all equipment, cables, cross-connects, and their termination locations. CLRs are extremely beneficial when troubleshooting.
A flash cut transfers the old system to the newly installed system in one continuous process until it is 100% complete. Transfers may involve a hot cut or a rolling cut. To perform a hot cut, you unplug the equipment cables from the existing system and plug them into the new system. The customer is without communications during the process. The rolling cut is a type of flash cut in which you relocate cross connects one pair after another until the transfer is complete.
In a phased cutover, you transfer portions of the old system to the new system in groups. As you rewire offices or buildings, you phase them into the new system. In this example, the new and old systems work in parallel until you complete the transfer.
Removing abandoned cable is an essential part of most retrofits. Abandoned cable is a fire hazard you must address. In a fire, old cable becomes fuel, providing a path for the fire to spread throughout the building. It also takes up valuable pathway space and places an unnecessary strain on the supporting hardware. Don't forget to obtain written permission from the owner before removing any cable.
This correspondence course is offered in conjunction with BICSI, but is not directly sponsored by the organization. The intent of the course is to help students prepare for the written portion of the BICSI Installer Registration Program. This BICSI program also requires hands-on training, which is outside the scope of this correspondence course. This course is also offered as continuing education for those already registered as a BICSI apprentice, installer, or technician.