BICSI Installer 2 Fiber common mistakes
BICSI Installer 2 Fiber · Understand the traps and how to avoid them.
Treats dB and dBm as interchangeable, e.g. writes that a 3 dB loss 'brings the source down to 3 dBm', or adds a source output in dBm directly to a cable loss in dB and reports the result as a power level.
Formulas are memorized as symbol patterns without attaching physical meaning to each unit, and the exam deliberately mixes loss-budget and absolute-power questions in the same item set.
What to do instead
Adopt one rule and apply it every time: dB is always a ratio (a difference), dBm is always an absolute level referenced to 1 mW. Drill ten conversions where a known dBm launch level has a dB loss subtracted, and state the units out loud at each step before choosing an answer.
Misassigns core/cladding dimensions and operating wavelengths when identifying a fiber type, such as labelling 50/125 um multimode as singlemode, pairing 850 nm with OS2, or claiming OM5 supports 1550 nm transmission.
Fiber types are studied as names rather than as a table of physical attributes, and the similar '50/125' numbers across OM2 through OM5 blur together under time pressure.
What to do instead
Build a one-page matrix before exam day: 62.5/125 (OM1) and 50/125 (OM2/OM3/OM4) at 850/1300 nm, OM5 50/125 wideband at 850/953 nm, and 9/125 (OS1/OS2) at 1310/1550 nm. Rehearse it until the wavelength follows the fiber type automatically.
Selects cable on optical performance alone and ignores the fire-resistance listing, for example specifying an OFNR riser cable for a run through an open ceiling used as a return-air plenum.
Study time concentrates on loss and bandwidth, so the jacket listing is treated as a purchasing detail rather than a code requirement, and the installation environment is not read carefully in the scenario.
What to do instead
Classify the space first (plenum / riser / general purpose), then choose the listing: plenum-rated for return-air spaces, riser-rated for vertical shafts, general-purpose elsewhere. Make 'what space is this cable in?' the first question on every cable-selection item.
Mates an APC connector to a UPC adapter or assumes all singlemode connectors are interchangeable, then reports the resulting high loss or damaged endface as a bad splice.
Both are 'singlemode connectors' visually, and the 8-degree endface angle is invisible without a scope, so the mismate is only noticed as an unexplained loss number.
What to do instead
Tie polish to colour and geometry: APC is angle-polished, green, low reflectance; UPC is flat-polished, blue/beige. Never mate the two, and check housing colour and ferrule angle before connecting anything in a scenario question.
Applies the bend-radius multiplier to the fiber core or to the connector body instead of the cable outside diameter, and uses a single multiplier for both the installed and the pulling condition.
The rule is remembered as 'ten times' without the reference dimension, and the difference between static installed radius and dynamic radius under load is not connected to the pull plan.
What to do instead
Always take the outside diameter from the jacket, then apply the manufacturer's figures - commonly about 10x OD installed and about 20x OD while under tension, with the datasheet governing. Write the two numbers into the pull plan before the pull starts.
Pulls fiber by hand-wrapping the cable and judging tension 'by feel' with no breakaway swivel or tension meter, exceeding the manufacturer's maximum pulling tension and stretching the cable.
Copper pulling habits transfer directly, and fiber feels light and tough in the hand, so the tension limit is never checked against the datasheet during short indoor pulls.
What to do instead
Set a hard limit from the datasheet - commonly 25 lbf (110 N) for premise cable unless stated otherwise - and enforce it mechanically with a breakaway swivel or in-line tension gauge. Attach the pull to the strength members or jacket, never to the fiber, and record the limit on the pull sheet.
Skips endface inspection, cleans only after a link fails, and mates connectors dry, or cleans with a dry wipe alone when the contamination is oil-based.
Inspection scopes are seen as a troubleshooting tool rather than a mandatory step, and the microscopic size of the contamination makes the failure invisible until loss or reflectance shows up in testing.
What to do instead
Make it a fixed sequence for every termination and every mate: inspect at high magnification (higher magnification for singlemode), wet-clean, dry-clean, re-inspect, then connect. Reject and re-terminate any endface with scratches, pits, or persistent debris.
Cleaves by scoring and snapping with a general-purpose tool or reuses a worn cleaver blade, producing an angled or misty endface that is then spliced or terminated without verification.
Attention goes to which tool is being used rather than to whether the result was verified, and cleave quality is invisible without magnification.
What to do instead
Treat the cleave as a measurable step: confirm a flat, perpendicular endface at high magnification before every splice, keep the cleaver in calibration, and never re-cleave with a tool that has a chipped blade. Check the splice-estimated loss on the splicer after each arc.
Sets the optical loss test set reference in a configuration that does not match the reported test method, then reports negative loss values or inflated losses that include the reference cords.
The reference method is studied as a procedure rather than as a definition of what the number means, and the negative reading is treated as an instrument fault instead of a setup error.
What to do instead
Learn the reference configurations and match the reference to the reported method, count the mated pairs your result includes, and sanity-check every reading: about 0.75 dB maximum per mated connector pair for a passing link. A negative loss means the reference included something the test does not.
Reads an OTDR trace from one end only and misidentifies a ghost reflection or a gainer as a real event, or reports splice loss that includes the launch and receive cables.
The trace is read as a picture rather than as a calibrated distance-versus-loss plot, and unidirectional testing hides events that are direction-dependent.
What to do instead
Read the trace left to right against the distance and dB scales, identify launch and receive cable first, and recognize gainers and ghosts by their shape and by repeat distance. Confirm suspect events with a second test from the far end and cross-check the total with a light source and power meter.
Treats a shared pathway and an unterminated connector casually - routes fiber in the same raceway as power or Class 1 circuits without verifying separation requirements, and looks into or leaves open a live connector to 'check for light'.
Safety and code content is skimmed as common sense, and the laser hazard is underestimated because the light is invisible and the fiber looks inert.
What to do instead
Memorize that optical fiber must be separated from electric light, power, Class 1, and non-power-limited fire alarm conductors in a shared pathway unless a barrier or the code permits otherwise, that the space's rating drives the cable listing, and that every unterminated fiber is treated as energized - never look into it, cap it, and use the correct eyewear and signage.