Pre-planning the cable pull saves time and increases productivity

Oct. 1, 1996
In cable pulling, as in every line of work, ideal situations are rarely encountered; installers and technicians must, therefore, use creative thinking and ingenuity on each installation.

In cable pulling, as in every line of work, ideal situations are rarely encountered; installers and technicians must, therefore, use creative thinking and ingenuity on each installation.

Bruce Foreman and Rick Keeler,

Fishel Technologies

The art of cable-pulling is not new; however, proper planning is often overlooked, which can lead to added costs and more work for installers and technicians. A little foresight can save the cost of having to re-pull cable runs that may have been damaged during the initial installation. In addition, scheduling multiple cable runs to be pulled at one time will reduce labor costs for each installation.

Every cable pull is unique, and all the different factors must be weighed at the pre-planning stage; however, the following step-by-step installation procedure can serve as a guideline for preparing for the cable pull. It is intended to help installers set up and place copper or fiber-optic cables efficiently and effectively. The process can be broken into eight basic steps: Identify the environment where the cable pull will be made; identify the cable type and specifications; establish the cable route; install the necessary hardware for cable support; set up the cable reels and cable cart; label according to the Tia/eia-606 standard; position the technicians for the cable pull; and, finally, pull the cable.

Before installers or technicians start work on the job site, they must identify the type of environment or building structure where the cable will be placed. The Bicsi Telecommunications Distribution Methods Manual identifies five different systems for horizontal-cable distribution: underfloor duct, poke-through, conduit, raised-floor and ceiling distribution.

In retrofitted buildings, the overhead ceiling distribution system is most often used. This type of environment includes drop-ceiling tiles, locked-ceiling tiles, solid ceilings with access panels, solid ceilings with cable raceway and overhead-conduit systems.

For new building construction, architects and engineers tend to recommend and design overhead-distribution systems. The date of the building`s construction is a major factor in ease of installation; for example, older buildings often have locked ceiling tiles or solid ceilings with access panels. These can be more time-consuming and more difficult to access than drop-ceiling tiles. Another example would be school buildings built in the 1950s, which may not have an overhead-ceiling space; therefore, technicians will need to use conduit systems or surface raceways to route the cable.

A horizontal-cabling distribution system that is common in new construction is the underfloor method. The two main underfloor systems are poke-throughs and underfloor duct.

Whether the distribution system is underfloor or overhead, it is important to identify which tools and methods will be needed to set up for that type of cable pull.

Identify cable type

The second step in preparing for the cable pull is to identify the cable type and specifications. Most installations include Category 3 cable for voice, Category 5 cable for data, and possibly coaxial or fiber-optic cable for video applications. As data rates and bandwidth requirements continue to escalate, fiber-to-the-desktop will continue to expand into the end-user environment.

Depending on the pathways and spaces where the cable is placed, a plenum or nonplenum jacketed cable can make a difference in the difficulty of the pull. Plenum cable may be required if the cable must be placed in a return airspace. Some plenum cables using Teflon or fluorinated ethylene propylene can be easier to install than others. Because of the different compounds used to manufacture plenum cable, the cable jackets vary in slickness and overall diameter. The same is true in a poke-through conduit system. Although plenum cable can be more expensive to use, small conduit sizes and multiple cables in the same conduit may leave the installer with no alternative.

Cable specifications also play an important role in setting up for the cable pull. Consider the following characteristics in each cable:

- Pulling tension

- Bend radius

- Maximum distance

- Outside diameter of the cable

- Conduit-fill ratios.

The Tia/eia-568A standard specifies that the pulling tension for Category 5 cabling shall not exceed 25 lbs. If pulling tension exceeds 25 lbs, it can alter the electrical characteristics and degrade the performance of the cable. When testing cables for Category 5 compliance, any cables stretched beyond the 25-lb pulling tension may fail cable-performance tests, and the technicians will have to pull the cables again.

Bend radius is also a key concern when preparing for the cable pull. Exceeding the recommended bend radius can also alter the electrical characteristics of the cable. Manufacturers recommend the minimum bend radius for their cables based on the outside diameter of the cable jacket. Note: Cable bundles must not be installed in sharp 90-degree bends.

The Tia/eia-568A standard specifies a maximum distance of 90 m for 100-Mbit/sec applications in a Category 5 channel model. If distance limitations are exceeded, tests for Category 5 compliance will fail, and again require repulling cables. Noncompliance with standards can double the amount of rework and cause frustration for the installers.

Overall diameter of the cable is another important factor in determining the number of cables that can be pulled at one time. A bulky cable bundle is difficult to pull, especially in conduit. To prevent cable-jacket burn and excess pulling tensions, consult conduit-fill ratio tables before setting up for the cable pull.

For the third step in preparing for the cable pull, installers must establish the cable route, deciding on the most efficient pathway -- assuming that the distribution system has not been determined. The cable route should travel down main passageways, such as halls and corridors, following the building`s structural lines.

The main cable route should maximize the number of stations pulled; for example, individual stations may branch off the main pathway to make the most of the cable installers` efforts. It is crucial to keep the number of 90-degree bends to a minimum: For conduit systems, no more than two 90-degree bends should occur within a 100-ft cable span without a pull point. Too many bends in the main cable route increase the need for additional technicians at each 90-degree turn. Finally, to minimize disruption to office employees in the area, installers should try to avoid running the main cable bundle across offices.

Before beginning the cable pull, the installer should examine the route for trouble spots where the cable might snag. To minimize electrical interference and potential cable damage, avoid electrical cables, fluorescent lights, sprinkler systems for fire-alarm systems and hot water pipes. Inaccessible areas such as extremely high ceilings also increase the effort required by installers; therefore, choose the cable route carefully to avoid unnecessary work.

The next step in preparing for the cable pull is to install cable-support hardware. Several hardware choices are available, the most common of which are bridle rings, J-hooks, cable trays, conduit, and cable raceways. Some may be easier or more cost-effective to use than others, depending on the environment; however, bridle rings or J-hooks in overhead ceiling structures are most likely to provide a cost-effective solution. Use caution to secure the necessary beam clamps and bridle rings so that they support the weight of the installed cables.

Setting up and labeling

The installer is now ready to set up for the cable pull. In determining the ideal location to initiate the pull, installers have two choices: Pull from the telecommunications closet on each floor to the individual workstations, or pull from the largest group of workstations back to the telecommunications closet.

Next, the installer must identify the total number of stations that can be pulled at one time. Some planning before the job starts will allow the installer to pull multiple runs to one area. Extending the arms of the cable cart can increase the number of cables pulled. Another suggestion is to slide 1-inch pipe over the arms of the cable cart so that more reels can be added.

The cable cart should always be set up to reduce the amount of cable strain on the cables; for example, avoid sharp entry angles into the conduit or the first bridle rings. In existing building areas, small, lightweight cable carts may be easier to set up and move than larger carts. Again, it depends on the environment.

Labeling, the sixth step in the process, is important: Without proper labeling, the cables need to be toned and tagged, which can double the time the installer spends on the job. Choose a labeling scheme that easily identifies the location, cable and jack position at the workstation. One example to simplify the identification process is an alphanumeric labeling scheme such as 1A, 1B, 1C, 2A, 2B, 2C and so on. Maintaining a consistent and standardized labeling methodology can help ensure that future pulls follow the same format.

It is a good idea to print labels clearly (or use a labeling machine) so that technicians and end-users can easily decipher the number and location. To avoid confusion when it is time to terminate the cables, it is recommended that the installer simultaneously label cables, cable reels and field blueprints, before beginning the cable pull. It is suggested that installers use white glass tape and a sharp-point permanent marker, and also mark numbers such as six (6) and nine (9) with a line underneath to distinguish between the two. Finally, apply labels about three feet from the cable end to ensure that the labels remain intact when the installer cuts off the cable-bundle head.

When bundling multiple cables together, stagger the cables so that the head of the cable bundle is not too bulky. This will prevent the cable head from snagging on the bridle rings. You can also reduce snagging by securing the jet line or pull string with a half-hitch and taping down the cable bundle. Finally, to save time for the next pull along the same route, cable installers should trail the cable bundle with another jet line.

One of the most important steps for a successful cable pull is positioning the technicians. Ideally, each cable pull will have a technician monitoring the reel cart and another technician pulling the jet line to the intended location. In addition, it is recommended that a technician be positioned at each 90-degree bend. If there are not enough technicians on the job, then pull enough slack to the first 90-degree bend and repeat pulling slack to each of the 90-degree bends until the cable bundle reaches the intended location.

The final step requires careful monitoring and patience. To avoid cable stress or cable-jacket burn, installers must pull slowly and steadily. The technician at the reel cart feeds the cable to ensure that there is enough slack to reduce the amount of drag and stress on the cables.

At this step, it is important to reiterate that if the pulling tension exceeds 25 lbs of force, the Category 5 cable may not comply with the Tia/eia-568A standard and will have to be pulled again. Prelubricating the cable head, as necessary, will reduce friction in tight conduit pulls.

Two-way radios are invaluable if multiple stations are being pulled over a long distance. Continuous communication between technicians promotes a smoother cable pull and reduces the level of frustration. A few more important tips to consider are:

- Leave enough slack at each cable end to fish down the wall to the intended location.

- At the telecommunications closet, the technician should leave enough cable length to route the cables to the termination field.

- When dressing the cables in the telecommunications closet, plan the cable path ahead of time to leave enough slack.

Also keep in mind that aesthetics are important to the end-user and can leave a positive impression. To keep the work space clean and tidy -- and avoid confusion -- neatly coil the pulled cable bundles on the ground. This is especially true in larger cable installations. If you need to store cables overnight before termination, coil the cable bundles with electrical tape at the station locations. If you need to leave cables in the ceiling, tie-wrap the coils to the ceiling structure to keep them out of the way of other tradespeople. Too many cables piled haphazardly on top on one another invariably become tangled and kinked, and then the installer will have to untangle them when it is time to start terminations.

Eight Steps to Prepare for the Cable Pull

- Identify the environment of the cable pull

- Identify the cable type and specifications

- Establish the cable route

- Install the necessary hardware for cable support

- Set up the cable reels and cable cart

- Label according to the Tia/eia-606 standard

- Position the technicians

- Ready, set, and pull

Click here to enlarge image

At the governor`s office in Columbus, OH, Clint Kanuckel (left) and Chuck McConnell (right) get ready to pull and install Category 5 cable.

Bruce Foreman, registered communications distribution designer (Rcdd), is a communications design specialist and Rick Keeler is a technical sales representative at Fishel Technologies, Columbus, OH. In addition, Clint Kanuckel and Chuck McConnell, technicians at Fishel, made important contributions to this article.

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