Optical cables: types and construction
Before you splice, terminate or repair anything, you must know what is inside the cable. This lesson walks through the common outdoor and indoor cable constructions you will meet on FTTx and backbone projects, and how each one changes your preparation work.
- 1
Loose-tube outdoor cable (GYTA/GYTS)
Color-coded bare fibers sit in gel-filled loose tubes around a central strength member. Identify the tube color sequence (blue, orange, green, brown…) before opening, and clean the gel with cable prep wipes — residue causes bad cleaves and high splice loss.
- 2
Ribbon cable (GYDTA)
Up to 12 fibers bonded into a ribbon. Requires a ribbon splicer (e.g. TC-600M) and a ribbon-capable cleaver. Never separate ribbon fibers by hand before mass splicing — strip and cleave the ribbon as a whole.
- 3
Drop cable (GJXH/GJXFH)
The FTTH last-drop cable: 1–2 fibers plus steel or FRP strength members. The strength member must be separated and clamped separately at the subscriber terminal, otherwise tensile load transfers to the fiber.
- 4
Indoor soft cable (GJFJV)
Tight-buffered fiber with aramid yarn — used for patch cords and in-building runs. Strip the buffer with a proper stripping tool; pulling it off by hand leaves fiber nicks.
- 5
Armor and rodent protection
Corrugated steel tape (GYTA53) needs an armored cable opener; cutting through armor with side cutters risks damaging the tube underneath.
Field tips from TEKCN engineers
- Always match the fiber color code to the port order before closing a splice closure — re-work after closing is the most common field time loss.
- Record cable structure (tube count, fibers per tube) in your splicing report; it speeds up fault location months later.