However, most of the techniques of fiber optic cable installation has been borrowed from those used for copper cables. And currently the majority of fiber cable contractors come from the copper network background.
Fiber cables can be divided into two big groups: outdoor cables and indoor cables. Outdoor cables are laid along rights of way leased or owned by telecommunication carriers, and they are well marked after the cables are installed. The telecommunication carriers have their own team of cable installers and they seldom outsource the job to independent contractors.
Most independent fiber cable installation contractors install indoor cables most of the time. Indoor fiber cables are mostly used as the backbone for campus networks, enterprise LAN systems and etc.
And there is the submarine cable category. They are laid from ships built for that purpose. They are only used by the big global network backbone builders.
But actually there are many small divisions within each group. So let's examine them one by one.
1. Submarine cables. Submarine cables are laid from ships built for that purpose. They are buried in a trench dug on the sea floor at depths of less than 200 meters. In areas deeper than that, submarine cables are directly laid on the ocean floor.
2. Direct-buried fiber cables. Direct-buried cables are also called armored cables. They have aluminum foil wrapped around for mechanical protection from rodent bite and outside forces. They are laid in a deep trench dug with a cable plow and then covered with dirt.
3. For outdoor cables excluding direct-buried cables, cable ducts are needed. Cable ducts are plastic tubes which provides a path and protection for outdoor cables. They are buried in trenches and then covered with dirt. Cable ducts have a variety of sizes and flexibility, they can range from one inch up to a 6~10 inches. Some are flexible while the others are pretty rigid.
4. Cable ducts are buried first without any fiber cables inside. They can be routed directly between two endpoints or through a series of access points at manholes.
5. Outdoor cables are then pulled through the cable ducts with pulling rope. The pulling rope is attached to the strength member of the cable and then pulled from the destination point. You should never pull the fibers directly since that will break the fibers easily and result in a useless broken cable for you.
5. And then there are aerial cables. One type of aerial cable has a messenger line built-in which provides mechanical support and they can be hanged on poles without any lashing. This type of aerial cable is called figure 8 or self-supporting cable. Other types of aerial cables have to be lashed with a special lashing wire running around both the cable and the separate messenger wire.
6. Indoor cables can be installed within walls, through cable risers, or elsewhere in buildings. Note: only special under carpet fiber cable should be used for laying on the floor where people walk.
7. A special type of indoor cable is called plenum cable. They have special formulated out jacket material for fire rating. Only plenum cables can be used in air return spaces for the VAC system.
We've covered a lot about fiber cable installation in this short article. By warned - you should always browse some training material on fiber cable installation before try it yourself!
Fiber Optic Cable Installation
Cable installation must also meet the NEC(National Electric Code) and local building codes. NEC indicates that fiber optic cables can be placed in the same raceway, cable tray or enclosure with CATV, telephone, communication circuits and Class 2 and 3 remote control signaling circuits.
Note that you should never put the fiber optic cable in the same enclosure that houses electrical terminations.
What are conduits?
Conduit is a tube or trough for protecting electrical or communication wires and cables. It may be a solid or flexible tube in which cables are run. They house and protect the fiber optic cables as well as any other type of data or communication transmission line.
Underground conduits are also called ducts and consist of one or more conduits spaced closely together. They are often buried directly in the ground in concrete casing. Duct lines terminate in underground vaults called manholes. Conduits are made of fiber, PVC, PE and other materials.
Above ground conduits are made of metal or nonmetal materials. They can be used in exposed or concealed locations aboveground.
Characteristics of a good conduit installation
1. Good mechanical properties to withstand the forces imposed by cable installations
3. No sharp edges or bends touches the fiber optic cables throughout the route
4. Meets current and future expansion requirements
What are cable trays?
A cable tray is an assembly of units made of metal or other noncombustible materials that form a continuous, rigid support for fiber cables. Cable trays are used throughout the industry and they greatly simplify the installation of fiber optic cables.
Cable trays come in several different types including ladder type, trough type, channel type and solid-bottom type.
Ladder type cable tray is a metal structure consisting of two longitudinal side rails connected by individual transverse members. The transverse members provide the support for fiber cables.
Trough type cable tray is also a metal structure. It consists of a ventilated bottom and has closely spaced supports within integral or separate longitudinal side rails.
Channel type cable tray consists of a one-piece ventilated or solid-bottom channel section.
Solid-bottom type cable tray is a metal structure that has no openings in the bottom. Integral or separate longitudinal side rails provide the support for the fiber cables.
What are pull boxes?
Pull boxes are used to break up long conduit lengths for easier and lower tension cable pulls.
Pull boxes are usually placed near conduit bends and in long straight runs. You should use at least one pull box after every second 90° bend and in long conduit spans.
When pulling cable out of pull boxes, ensure that the cable's minimum bend radius is always observed. Cable pulled through a corner pull box should first be pulled into a loop since the sharp corner of the pull box can easily damage the cable and the fibers.
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