:: Environment requirement on outdoor fiber optic cables
Outdoor fiber cables must endure harsh environment factors such as UV radiation from sunlight, storms, snows and 80 mph wind, so outdoor cables must be strong, weatherproof and UV resistant. The outdoor cable should also be able to endure the wild temperature variations both during installation and throughout its life span.
These factors determine the materials used for the cable construction. Various materials are used to suit the installation environment.
Outdoor cable jacket is treated to prevent UV light from penetrating inside the cable and damaging the internal glass fibers. Extra UV protection specification can be specified if needed.
:: Environment requirement on indoor fiber optic cables
Indoor fiber cables should be strong and flexible for easy pulling and installation. They should also possess NEC required fire and smoke ratings. As a industry standard practice, single mode fiber jacket is yellow and multimode fiber jacket is orange.
:: Popular cable materials in fiber optic cable construction
1. PVC (Polyvinyl Chloride)
1) Good resistance to environmental effects. Some formulations are rated for -55C to +55C.
2) Good flame retardant properties. Can be used for both outdoor and indoor fiber optic cables.
3) PVC is less flexible than PE (Polyethylene)
2. PE (Polyethylene)
1) Popular cable jacket material for outdoor fiber cables
2) Very good moisture and weather resistance properties
3) Very good insulator
4) Can be very stiff in colder temperatures
5) If treated with proper chemicals, PE can be flame retardant
1) Good flame-resistance properties
2) Low smoke properties
3) Good flexibility
4) Most often used for indoor fiber cables
4. Kevlar (Aramid Yarn)
Aramid yarn is the yellow fiber type material found inside cable jacket surrounding the fibers. It can also be used as central strength members.
1) Aramid yarn is very strong and is used in bundle to protect the fibers
2) Kevlar is a brand of aramid yarn. Kevlar is often used as the central strength member on fiber cables which must withstand high pulling tension during installation
3) When Kevlar is placed surrounding the entire cable interior, it provides additional protection for the fibers from the environment
5. Steel Armor
Steel armor jacket is often used on direct burial outdoor cables and it provides excellent crush resistance and is truly rodent-proof. Since steel is a conductor, steel armored cables have to be properly grounded and loss fiber optic cable's dielectric advantage.
1) Outdoor direct burial cables
2) Fiber cables used for industrial environment where cables are installed without conduits or cable tray protection
1) Provides excellent crush resistance for outdoor direct burial cables
2) Protects cables from rodent biting
3) Decreases water ingress into the fiber which prolongs the fiber cable's life expectancy
6. Central Strength Member
For large fiber count cables, a central strength member is often used. The central strength member provides strength and support to the cable. During fiber optic cable installation, pulling eyes should always be attached to the central strength member and never to the fibers. On fiber splice enclosure and patch panel installations, the cable central strength member should be attached to the strength member anchor on the enclosure or patch panel.
About the author:
Colin Yao is an expert on fiber optic technologies and products. Learn even more about plastic optical cable, plastic optical fiber pof and plastic optical fibers on Fiber Optics For Sale Co. web Site.