Never directly pull on the fiber itself. Fiber optic cables have Kevlar aramid yarn or a fiberglass rod as their strength member. You should pull on the fiber cable strength members only!
Never exceed the maximum pulling load rating. On long runs, use proper lubricants and make sure they are compatible with the cable jacket. On really long runs, pull from the middle out to both ends. If possible, use an automated puller with tension control or at least a breakaway pulling eye. Know and observe the maximum recommended load rating of the cable.
Never exceed the cable bend radius. Fiber is stronger than steel when you pull it straight, but it breaks easily when bent too tightly. These will harm the fibers, maybe immediately, maybe not for a few years, but you will harm them and the cable must be removed and thrown away!
Always roll the cable off the spool instead of spinning it off the spool end. This will put a twist in the cable for every turn on the spool! Never twist the fiber cable. Putting a twist in the cable can stress the fibers too.
Make sure your fiber cable is long enough for the run. Fiber splicing make things complicated and expensive. And it needs special protection. Try to make it in one pull.
Indoor cables can be installed directly, but you might consider putting them inside innerduct. Innerduct provides a good way to identify fiber optic cable and protect it from damage, generally a result of someone cutting it by mistake! You can get the innerduct with pulling tape already installed.
Plan the Installation. Create a detailed, written plan of installation. You can eliminate 95% of the problems installers can encounter by simply creating this plan. The plan should include equipment and supplies, fiber cable specification, location of equipment, testing requirements, data forms for testing, personnel experience level and assignment, installation methods, identification of potential problem areas, safety issues, etc.
Pull, do not push cables. Pushing can result in violation of the bend radius.
Monitor the supply reel. Monitoring the supply reel during installation is necessary to prevent violation of minimum bend radius.
Communicate along the path of installation. When installing long runs, communicate and monitor along the path of the installation. Fiber cables can and do jump from unmonitored pulleys. The minimum crew should have one person monitoring the pulling equipment, one monitoring the supply reel, and one coordinating all involved in the installation.
Use proper tools and techniques. A vehicle for pulling the cable is not a proper tool, unless a breakaway swivel is also used. Proper techniques depend on the cable design and the location of the installation. For example, proper technique is pulling a cable into a conduit. Proper technique is placing or laying a cable in a cable tray or raceway.
Use fiber optic cable lubricant. Lubricate the cable when installing in conduits. Lubrication reduces the pulling load and the chance of breakage. The lubricant has to be compatible with the cable jacket material.
Train installation personnel. Properly train and instruct the people who will do the installation. Proper training reduces expense through reduction of breakage and excess attenuation.
Use the figure 8 technique. Divide long pulls into several shorter pulls, using the figure 8 technique for storing cable at the intermediate locations. The cable is placed on the ground in a figure 8 pattern. This pattern is large, at least 10-20 feet from top to bottom of the pattern. When all the cable is placed in this pattern, the pattern is lifted and flipped over, so that the loose end is on top. This loose end is pulling into the next section of conduit or duct. This technique prevents twisting in the cable.
Comply with vertical rise limits. Know and observe the maximum vertical rise distance limit. Exceeding this limit can result in fiber breakage, excess attenuation, and, in loose tube cables, fibers sliding from cables. Cables in vertical installations that are longer than the vertical rise limit must be tied off at distances less than this limit. Loose tube cables must be looped.
Allow for thermal expansion and contraction. In outdoor installations, a common practice of 2.5 foot sag for 150 foot span is good for thermal expansion and contraction. Failure to allow for thermal expansion can result in increased attenuation and breakage of fibers.
For tough installations, use loose buffer tube fiber cables. Loose tube cables can be more forgiving of abuse than tight buffer cables. The reason is that the excess length of fiber in the buffer tube and the ability of fiber to move from low stress region to higher stress region.
Observe the temperature operating range. Install a cable in locations in which the temperature range imposed is within the temperature operating range. Violation of the temperature operating range can result in excessively high attenuation.
Cap or seal water blocked cables. Cap off or seal the ends of cables with water blocking gel or grease. These materials can flow out of the cable, causing maintenance problems in cable end boxes.
Protect fibers and buffer tubes. Confine fibers and buffer tubes in protective structures, such as splice trays and cable end boxes. Fibers and buffer tubes do not have sufficient strength to resist breakage due to normal handling of copper cables.
Loop vertically installed loose tube cables. Install vertical, unfilled, loose tube cables with loops to prevent the fiber from slipping to the bottom of a vertical run. If this happens, attenuation can increase and fibers eventually break.
Check continuity and attenuation. Check the continuity and attenuation of the cable before each operation. These checks should be performed as-received/before installation, after installation, after splicing, and after connector installation.
Mark cable as “Fiber Optic Cable”. Mark cable as “fiber optic cable” in all locations in which it can be easily reached. Such marking will alert electricians to the nature of the cable.
Make As-Built Data logs. Make as-built data logs on all cables. Keep these data available to those who will perform maintenance and troubleshooting. These data logs should include both insertion loss measurement and OTDR measurements.
Safety precaution – no food, drink or smoke. Do not eat, drink, or smoke in any area in which bare glass fiber is created. Bare glass fibers can cause splinters which are very difficult to find and remove.
Safety precaution – do not look into fiber without checking status. Never look into a fiber, cable, or connector unless you know for sure that there is no laser light in the fiber. For extensive work with fiber optics, safety glasses with IR filter is recommended.
Leave service loops. Leave cable and fiber service loops everywhere. You will regret not doing so. Service loops allow you to pull excess cable or fiber into a location where you have experienced a problem. It is much cheaper to pull in a service loop than to replace an entire run of fiber cable.
Segregate or isolate the work area. Rope off or otherwise isolate the area of cable installation to prevent access to unauthorized or untrained personnel. This will avoid safety problems such as fiber splinters and unintentional abuse.
For direct burial installations, the cable should lie flat in a trench, free of any large stones or boulders that may deform the cable.
Do not allow vehicles to drive over a cable.
Ensure that the proper cable length has been installed before cutting off excess cable.
Avoid placing cable reels on their sides or subjecting them to shock from dropping.
Fiber optic cables should be placed in their own dedicated ducts or trays. Do not mix copper cable and fiber cable in the same ducts or trays.
After the fiber optic cable is installed into a duct or innerduct, end plugs should be installed to provide an effective water seal. The ducts and innerducts should be kept free of debris and maintained watertight at all times.
Ducts and innerducts should be sized to meet present and future cable installation requirements. A maximum 40% fill ratio is a good rule of thumb to follow for duct size.
The fiber pulling rope or tape should be sequentially marked (foot or meter) for easy identification of distance.
The pulling tape should have a rating for greater than maximum anticipated pulling tension.
Before the start of any cable pull, all ducts and cable vaults should be carefully inspected for damage or deterioration, and to address any safety concerns.
The electric spark generated by a fusion splicer can cause an explosion when flammable gases are present. Fusion splices should therefore not be used in vaults.
To minimize cable tensions, reel vault locations should be set near the sharpest bend locations. Pulling and reel locations should also be set at corner vaults where possible.
Identify lightwave equipment that will be used and ensure that the equipment will function properly with the fiber cable being installed.
When an outdoor rated fiber cable enters a building, it should be spliced to an indoor-type fiber cable within 50 feet from the cable entrance to meet NEC code.
All vertical cable must be secured at the top of the run. A split mesh grip is recommended to secure the cable.
The vertical attachment point should be carefully chosen to comply with the cable’s minimum bend radius while holding the cable securely.
If future cable pulls in the same duct or conduit are a possibility, the use of innerduct to sectionalize the available duct space is recommended. Without this sectionalization, additional cable pulls can entangle an operating cable and could cause an interruption in service.
A small amount of slack cable (20-30 feet) can be useful in the event that cable repair or relocation is needed.
Cables should be tested after shipping. Damage to cabling can occur during shipping or installation. Failing to test fiber cabling after it is delivered is a common mistake made by installers.
If insertion loss suddenly increases with an adapter or connector, the cause may be dirt. You should always clean the connector and adapter before plugging them in.
Properly attach the pulling eye and swivel to the cable. Ensure that the pulling eye and swivel assembly have no sharp edges and can easily fit through all conduits, pull boxes, and cable trays.
When pulling the fiber out of a section, coil the cable on the floor in a figure 8 pattern to avoid twisting. Continue the cable pull until all the cable has been pulled through.
Identify the exact fiber optic cable route and ensure that it meets all installation specifications. Obtain all required fiber cable installation authorizations and permits along the route.
Record all required fiber optic facility details, including proper route drawings, fiber assignments, loss readings, OTDR traces, etc.
Prepare emergency repair plans.
Only remove connector and adapter duct caps prior to making the connection. Do not let the connector tough any surface once the duct cap has been removed.
When making a connection, the connector should attach to the adapter smoothly. Do not rotate the connector when making the connection.
For screw-in connectors such as FC connector, tighten them only “finger tight”. Never force a connector onto an adapter.
A fiber optic cable should be tested three separate times during an installation: on the reel, the splicing test, and the final acceptance test.
Extreme caution should be observed when performing an aerial installation. The proper personnel should be contacted so that they are on the site when work is performed near high-voltage lines.
Cables that are installed in the vicinity of high-voltage power lines should be grounded, including all-dielectric cables.
Maintain proper clearance between the fiber optic cable and power cable at all times. Always make allowances for power cable sag due to weather and current conditions. Cable sag increases in warm weather or when power cable is passing heavy current.
When a steel messenger wire is used for aerial installation, avoid zigzagging the messenger wire from one pole side to the other. Instead, make sure it is kept on one side as much as possible.
Follow Building Codes: Always obey all local, and national, fire and building codes. Be sure to “firestop” all cables that penetrate a firewall. Use plenum rated cable where it is mandated, etc., etc.
Do make every effort to pull cables from a conduit in as straight an angle as possible. Pulling on an angle can cause damage to the cable.
Use a generous amount of cable pulling lubricant on the entire run, especially on the leader (pulling eye & mesh). The person may stop the cable pull from time to time to prepare and apply more lubricant. Use only lubricant that is expressly designed for cable pulling. When working in freezing temperatures, use a lubricant that is designed not to freeze.
It is important to use a rope size that give minimal stretching during the pull. Stretching of the rope is undesirable for several reasons including that it makes for a very unstable pull, and takes away control from those doing the pulling.
Use extreme caution when removing the pull eye. Do not use a blade to slit the mesh. Instead, use a pair of electricians scissors or diagonal cutters. Work your way from the back of the cable toward the pull eye, while lifting the mesh upward, away from the cable.
It is extremely important to take an accurate measurement when planning an order for a custom pre-terminated fiber optic cable assembly. These custom assemblies cannot be returned unless out of box defective.
Optional pulling eyes are highly recommended. The pulling eye (and associated cable netting) will protect the pre-terminated ends during the pull.
Underground conduits, if newly installed, should be a minimum size of between 1.5″ to 2″. If the run is long, or if you anticipate the possibility of additional future pulls; Then you may want to install a conduit of up to 4″ (or greater).
Try to design the conduit run with a few bends as possible. If there are too many bends in the run then you may consider installing junction boxes in lieu of bends.
Cable may be placed in a Figure 8 pattern if it needs to be removed from the reel. This pattern minimizes the accumulation of cable twist. Care should be taken to prevent cable damage while the cable is in this configuration.
The cable should not be installed in environments exceeding its specified maximum and minimum installation temperature. For loose tube and ribbon cable this is typically specified for an installation temperature of -30C to +75C.
Riser cables are generally required for vertical applications and plenum cables are required where there is a positive air pressure space.
The cable weight in an unsupported vertical rise shall be less than the specified long term operating load. Your manufacturer’s specification sheet should be consulted for specifics. Intermediate cable attachment points however are recommended for optimum performance.
Bonding and Grounding: Follow your company and local/national bonding and ground procedures when using fiber cable with metallic components.
When pulling the cable off the reel onto messenger mounted cable blocks, special care should be given to size and location of the 1st and last pulley. The reel should be placed as far as practical from the 1st pulley to minimize the angle of the 1st bend. A cable shoot/pulley larger than the specified bend radius is recommended to minimize the cable bend at the first and last pulley locations or at any location with a change in direction.
On runs from 40m to 100m, use proper lubricants and make sure they are compatible with the cable jacket.
On runs over 100m, use proper lubricants and pull from the middle out to both ends.
If possible, use an automated puller with tension control or at least a breakaway-pulling eye.
Avoid placing fiber optic cables in raceways and conduits with copper cables to avoid excessive loading or twisting.
Attach cables with plastic clamps having large surface areas. Avoid pinching or squeezing cable. Cable clamps should be installed manually with gentle pressure.
Use a wet wipe to loosen particles on the end of the cable connector using a circular or straight wiping motion while using care to avoid wiping over area of pad that has already been used. Do not use a back and forth scrubbing action.
Cleaning fiber optic transceivers. Choose an optical grade lint free swab that fits easily into the transceiver barrel. The swab should be gently placed into the barrel of the connector and rotate no more than one turn. DO NOT rotate back-and-forth or round-and-round because this could grind debris into the transceiver. The swabs should only be used ONCE.
Cable Blowing or Jetting in Duct Applications. A crash test should be performed to determine the maximum push force. Excessive pushing will cause the cable to cork screw in the duct or fold over which will damage the fiber.
Cable blowing. Consider the route to determine the maximum blowing distance. Follow the blowing equipment suppliers blowing distance recommendations; 3000 to 6000 feet is a typical blowing length. A set up with multiple blowing machines may be required.
Cable blowing. Maintain proper air flow to “blow” the cable verses “pushing” the cable. Use an air compressor with a minimum of 375 cfm. The minimum air pressure in the duct should be 100 psi with 125 psi recommended.
Cable blowing air cooler. Air compressor cooler should be used as recommended by the blower equipment manufacturer. Typically this is when the ambient air temperature exceeds 80˚F.
Cable blowing. Use only cable/duct lubricants recommended by its blowing equipment manufacturer for optical fiber cable.
Do not store cable within the closure or pedestal unless there is enough room to accommodate the minimum specified cable bend radius.
Grounding: Cable with metallic components shall follow the bonding and grounding requirements of the customer and local or national codes.
Midspan access of fibers in buffer tubes: To minimize fiber damage, use a Midspan Access Tool to open the buffer tube such as a Corning OFT-000. Care should be taken to use the correct insert size.
Conduit Installations General Information: Try to design the conduit run with a few bends as possible. If there are too many bends in the run then you may consider installing junction boxes in lieu of bends.
Use plastic bushings on conduit ends to avoid damage to the cable during the pull.
For cables using aramid yarn alone as the strength member, the jacket can be removed to expose the yarn. The yarn should be tied in a knot with the pull rope, so that the jacket will not be inadvertently used for strength. Optionally, the jacket can be tied into a tight knot before pulling. After pulling, the knot should be cut off.
For cables using aramid yarn and an fiberglass central member, a pulling grip should be used. The strength member should be attached independently. This can be accomplished by weaving the strength member into the fingers of the grip, and then taping it together. All strength members should be gripped equally to ensure proper distribution of tension.
Test jumpers must be of the same fiber core size, performance and connector type as the cable system (e.g. 50/125 μm FX2000 jumpers for a 50/125 μm FX2000 optical fiber system) and shall be one to five meters long.
Number of 90 degree turns. The number of 90 degree turns on a pull shall not exceed 6 for aerial cables and 4 for underground cable-in-conduit.
Pulling underground fiber optic cable. Special fiber optic blocks should be used on all turns or angles.
And always use a swivel pulling eye because pulling tension will cause twisting forces on the cable.
If cables are present in ducts through which the fiber cable is to be pulled, the existing cable types should be identified and the owner of the cable called to inform him of the action, and to identify any safety concerns.
