| :: Duct/Innerduct materials and colors: | | | | Fiber optic cable can be pulling into existing duct. The |
| Fiber ducts are usually made from HDPE (high-density | | | | duct should usually be oversized to allow future |
| polyethylene), PVC or other compound. They are | | | | cables be pulled in. |
| usually in black or gray. Fiber innerduct is usually | | | | :: Benefits of using fiber innerduct |
| orange or yellow. | | | | Fiber innerduct provides protection for the fiber cable |
| :: Why usually fiber ducts and innerducts are | | | | from being disturbed by other companies' cable |
| corrugated? | | | | installation operation. It also provides extra protection |
| Fiber ducts and innerducts are corrugated to provide | | | | from the environment. Or fiber innerduct can be used |
| the following benefits: | | | | in old duct installation. |
| 1. Decreasing pulling tensions during installation | | | | :: Things to keep in mind |
| 2. Very flexible and can be used in installation | | | | 1. Install end plugs |
| locations where many turns are involved | | | | After the fiber optic cable is installed into a duct or |
| 3. After installation, corrugated innerduct should be | | | | innerduct, end plugs should be installed to provide a |
| left for a day to allow the innerduct to retreat back | | | | water seal. No debris should be able to enter the |
| into the duct through its corrugated spring action | | | | duct or innerduct, and watertight should always be |
| :: The use of pulling tape | | | | maintained for the duct or innerduct. |
| Fiber optic cable pulling tape is preinstalled in fiber | | | | 2. Duct and innerduct should be properly sized for |
| duct and innerduct in the factory. This saves | | | | future expansion possibility |
| significant time during the installation process. Duct | | | | As always, planning for future expansion is crucial for |
| and innerduct can also be pre-lubricated in the | | | | real successful projects. A maximum of 40% fill ratio |
| factory, thus significantly reduces pulling tensions. | | | | is a good practice to follow. The duct size should be |
| :: Never bend over its minimum bend radius | | | | increased for long installation lengths with many turns. |
| Just like fiber optic cable, fiber duct and innerduct | | | | A larger duct can help to reduce cable-pulling tensions. |
| also have a minimum bend radius spec. Never ever | | | | Standard duct sizes vary from 3 to 8 inch ID and |
| should the duct or innerduct be bent tighter than its | | | | innerduct sizes vary from 0.75 to 2 inch. |
| minimum bend radius. | | | | :: The benefit of using duct lubricant |
| :: What is supported radius? | | | | Duct lubricant can significantly reduce the cable's |
| The supported radius is the minimum bend radius | | | | coefficient of friction, thus lessening the pulling |
| when the duct is bent around a supporting structure | | | | tension during cable pulling process. This is especially |
| such as in another duct or on a reel. | | | | important in long cable duct pulls and pulls with many |
| :: What is unsupported radius? | | | | turns. |
| The unsupported radius is the minimum bend radius | | | | Duct lubricant spillage should be cleaned up as soon |
| when the duct has no supporting structure in the | | | | as possible to prevent accident since it is very |
| bend. | | | | slippery. Manufactures' recommended procedure for |
| :: Benefits of using fiber duct | | | | cleaning lubricant provides good instruction on how to |
| Fiber duct protects the fiber cable and also provides | | | | do the cleaning. |
| an opportunity for future cable access and expansion. | | | | |