Simplex cable has one fiber, while duplex (zipcord) cable has two fibers joined with a thin web. Simplex (also known as single strand) and duplex zipcord cables are tight-buffered and jacketed, with Kevlar® strength members.
Because simplex fiber optic cable consists of only one fiber link, you should use it for applications that only require one-way data transfer. For instance, an interstate trucking scale that sends the weight of the truck to a monitoring station or an oil line monitor that sends data about oil flow to a central location.
There is a unique application where simplex cable can support two-way communications if the equipment can transmit and receive on two different wavelengths. For example, transmit could be at 1310 nm and receive could be at 1550 nm. This application is found more with single-mode cable.
Use duplex multimode or single-mode fiber optic cable for applications that require simultaneous, bidirectional data transfer. Workstations, fiber switches and servers, Ethernet switches, backbone ports, and similar hardware require duplex cable.
Indoor/outdoor cable uses dry-block technology to seal ruptures against moisture seepage and gel-filled buffer tubes to halt moisture migration. Comprised of a ripcord, core binder, a flame-retardant layer, overcoat, aramid yarn, and an outer jacket, indoor/outdoor cable can be run from building to building. Because indoor/outdoor cable is typically plenum-rated, it can be run from equipment room directly to the other equipment room without worrying about fire-safety codes or terminating the cable within 50 feet of the building’s entrance. The cable should be run in a conduit.
Interlocking armored cable is jacketed in aluminum interlocking armor so it can be run just about anywhere in a building. Ideal for harsh environments, it is rugged and rodent resistant. No conduit is needed, so it’s a labor–and money–saving alternative to using innerducts for fiber cable runs.
Outside-plant cable is used in direct burials. It delivers optimum performance in extreme conditions and is terminated within 50 feet of the building entrance. It blocks water with dry blocking, absorbent tape, or powder. If it is armored, it will require grounding. Outside-plant cables are also rodent resistant. If they are too used in aerial applications, they will have a messenger strength member. Outside-plant cables also have a much higher tensile strength and can withstand the rigors of long, campus-wide installations.
Distribution-style cables have several tight-buffered fibers bundled under the same jacket with Kevlar or fiberglass rod reinforcement. These cables are small in size and are used for short, dry conduit runs in either riser or plenum applications. The fibers can be directly terminated, but because the fibers are not individually reinforced, these cables should be broken out with a “breakout box” or terminated inside a patch panel or junction box.
Breakout-style cables are made of several simplex cables bundled together, making a strong design that is larger than distribution cables. Breakout cables are suitable for conduit runs and riser and plenum applications.
There are two types of fiber optic cable construction: loose-tube and tight- buffered. Both contain some type of strengthening member, such as aramid yarn, stainless steel wire strands, or even gel-filled sleeves. But each is designed for different environments.
Loose-tube cable is specifically designed for harsh outdoor environments. It protects the fiber core, cladding, and coating by enclosing everything within semi-rigid protective sleeves or tubes. Many loose-tube cables also have a water-resistant gel that surrounds the fibers. This gel helps protect the fibers from moisture, which makes loose-tube cable great for harsh, high-humidity environments where water or condensation can be a problem. The gel-filled tubes can also expand and contract with temperature changes. Loose-tube cable also has a higher tensile strength than tight-buffered cable.
But gel-filled loose-tube cable is not the best choice when cable needs to be routed around multiple bends, which is often true in indoor applications. Excess cable strain can force fibers to emerge from the gel.
Because loose-tube cable is typically 250 microns, you’ll need a fan-out kit to build up the individual fiber strands to 900 microns when making the transition at the entrance point from outdoor loose-tube to indoor to tight-buffered cable.
Tight-buffered cable is optimized for indoor applications. Because it’s sturdier than loose-tube cable, it’s best suited for moderate-length LAN/WAN connections or long indoor runs. It’s easier to install because there’s no messy gel to clean up and it doesn’t require a fan-out kit for splicing or termination. You can install connectors directly to each fiber.