How fibers become cables
Bare fiber cannot be installed; cables package it for the environment. Loose-tube designs float 250 µm fibers in gel- or dry-blocked tubes — the outdoor standard, immune to temperature cycling. Tight-buffered cables coat each fiber to 900 µm — flexible, easy to terminate, the indoor standard. Ribbon cables bond 12 fibers flat for mass fusion splicing of high counts. Every cable carries strength members (aramid yarn, FRP rods) that take the pulling tension — never the glass — and armored versions add corrugated steel against rodents and crush.
Fire and placement ratings
Building codes require listed cables: OFNP/plenum for air-handling spaces, OFNR/riser for vertical shafts, LSZH where smoke toxicity matters (most international projects). Outdoor-only cable may run at most a short distance indoors before transitioning to a listed cable at the entrance facility.
TIA-598 color code — memorize it
Fibers and tubes are identified by twelve colors in fixed order: Blue, Orange, Green, Brown, Slate, White, Red, Black, Yellow, Violet, Rose, Aqua. Fibers 13–24 repeat the sequence with a black tracer stripe. A technician who recites this sequence without thinking splices faster and never crosses fibers.
Handling rules
Respect minimum bend radius (rule of thumb: 20× cable diameter under tension, 10× at rest), observe the maximum pulling tension printed on the reel, pull from the top of the reel, and leave slack loops at every closure — the future repair depends on today's spare meters.