Fiber Optic Cable Pulling Tension Calculator
Estimate peak pull tension, bend drag, and safe working margin before you start the cable pull.
Full Breakdown
| Cable family | Max pull | Weight | Note |
|---|---|---|---|
| Indoor distribution | 200 N | 11 kg/km | Short risers |
| Loose-tube outdoor | 600 N | 22 kg/km | Duct pulls |
| Ribbon trunk | 900 N | 32 kg/km | Backbone |
| Armored rugged | 1400 N | 48 kg/km | Harsh routes |
| Route environment | Dry mu | Load factor | Best use |
|---|---|---|---|
| Cable tray | 0.08 | 12x | Open routes |
| Innerduct bundle | 0.12 | 25x | Closet spines |
| Conduit | 0.18 | 40x | Typical pull |
| Buried duct | 0.24 | 55x | Longest drag |
| Cable type | Install radius | OD multiple | Warning |
|---|---|---|---|
| Indoor distribution | 58 mm | 10x OD | Do not pinch |
| Loose-tube outdoor | 84 mm | 10x OD | Keep curve smooth |
| Ribbon trunk | 106 mm | 10x OD | Respect trunk shape |
| Armored rugged | 125 mm | 10x OD | Heavy cable, heavy drag |
| Scenario | Length | Bends | Typical note |
|---|---|---|---|
| Short patch lead | Under 10 m | 0 to 2 | Mostly tray |
| Closet riser run | 10 to 40 m | 2 to 4 | Vertical lift |
| Campus duct pull | 40 to 250 m | 4 to 10 | Use lube early |
| Outdoor backbone | 250 m+ | 6 to 12 | Check every bend |
The calculator keeps straight drag, vertical lift, and bend loading separate so you can compare the pull against the cable rating before installation.
When pulling fiber optic cables through a conduit, it is essential to manage the tension of the cable. If the tension on the fiber optic cable are too great, the glass fibers contained within the cable will break. If the fibers within the fiber optic cable break, you’ll have to splice in new sections of fiber optic cables or to install entirely new fiber optic cable.
Friction, gravity, and the bends in the route of the cable create the tension that develop in the fiber optic cable. Friction between the fiber optic cable and the conduit or tray creates tension; the more length of the route, the more friction is created. Gravity creates tension in the fiber optic cable on vertical rises in the route of the cable.
How to Pull Fiber Optic Cable Without Breaking It
Any bend in the conduit create tension on the fiber optic cable. Bends with a radius smaller than ten times the diameter of the fiber optic cable can damage the fiber optic cable. It is possible to reduce the tensions created by friction in the conduit by using lubricant in the conduit.
Using lubricant can reduce tension in the fiber optic cable by twenty percent or more. By using lubricant in the conduit, there is more margin in pulling longer lengths of fiber optic cable. It is also essential to use an appropriate pulling method for the job.
Using a winch can create tension peaks in the cable; a hand pull may allow for avoid these peaks in tension. The type of fiber optic cable will determine the maximum tension that the cable can take. For instance, indoor distribution strands can only take two hundred newtons of tension, while armored fiber optic cables can take fourteen hundred newtons of tension.
To provide additional safety in the fiber optic cable, use a safety factor of 1.5 times the maximum tension the fiber optic cable can take. Many fiber optic cable technicians makes mistakes in calculating the tension for fiber optic cable installation jobs. One mistake is failing to count every ninety degree turn along the route the fiber optic cable will take; failing to count these turns will lead to an underestimation of the tension that will be placed on the fiber optic cable.
Forgetting to calculate the weight of the fiber optic cable along vertical lifts is another mistake; failing to account for this will also lead to an increase in the tension on the fiber optic cable. Using preset scenario for fiber optic cable installation will help to mimic the environments where the fiber optic cable will be installed. Using these scenarios will ensure that all tension-related issues are account for.
It is also essential not to exceed eighty-five percent of the conduits utilization capacity. If the percentage of fibers within the conduit exceed eighty-five percent of the conduit’s utilization capacity, the tension on the fiber optic cable may become too greatly due to friction and the bends in the route of the fiber optic cable. Monitoring the tension on the fiber optic cable during installation is essential.
Using a probing tool will reveal any snags on the fiber optic cable. Using the lubricant on a small section of the fiber optic cable before pulling the entire length of fiber optic cable will also reveal any issue. Using tension gauges during installation will reveal the tension on the fiber optic cable.
While there are tools that can calculate the tension on the fiber optic cable, you should of used judgment to determine when to stop pulling the fiber optic cable. By managing the tension correctly, the glass fibers within the fiber optic cable will remain intact, and the fiber optic cable will remain able to function more corectly for a long time.
