OSP Cabling and Infrastructure
Core concepts
This domain covers the physical layer: optical fiber types, cable constructions, closures, pedestals, cabinets, and grounding. Candidates should know single-mode versus multimode use cases, loose-tube versus tight-buffered construction, and when to specify armored, toneable, or figure-8 cable. Understand splice closure types (inline, butt, dome), pedestal and cabinet placement, and the role of bonding and grounding in protecting plant and personnel. Familiarity with connector types, splice loss budgets, and test methods such as OLTS and OTDR is essential.
Traps to watch
Questions often blur bonding and grounding; bonding equalizes potential, grounding connects to earth. Another trap is assuming all fiber in a cable is usable; ribbon and loose-tube counts differ from available strands after assignment. Watch for confusion between splice loss and connector loss budgets, and between insertion loss and reflectance. Also expect questions on closure selection where the answer depends on whether the closure must be re-enterable or buried directly.
Worked rule of thumb
Build a loss budget before choosing hardware. Example: 2.0 km of single-mode at 0.35 dB/km = 0.7 dB; four splices at 0.1 dB = 0.4 dB; two connectors at 0.3 dB = 0.6 dB; total 1.7 dB. Compare with the system margin; if the margin is 3 dB, the design passes with 1.3 dB spare. State the wavelength and the assumed per-unit losses, because those assumptions are what exam questions test.