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ETA · Last updated November 2026

Fiber Optics Installer (FOI): free practice test

FOI is ETA International's stand-alone certification for premises fiber optic installers and the prerequisite for the Fiber Optics Technician (FOT). The written exam has 75 questions in 2 hours with a 75% pass mark and follows ETA's 14-area FOI competency list, which draws on TIA-568, TIA-526-14, TIA-455-57, ITU-T G.652 and G.671, Telcordia GR-326 and NEC Articles 250 and 770. A hands-on course is also required; this prep covers only the written exam.

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About the ETA FOI exam

FOI is ETA International's stand-alone certification for premises fiber optic installers and the prerequisite for the Fiber Optics Technician (FOT). The written exam has 75 questions in 2 hours with a 75% pass mark and follows ETA's 14-area FOI competency list, which draws on TIA-568, TIA-526-14, TIA-455-57, ITU-T G.652 and G.671, Telcordia GR-326 and NEC Articles 250 and 770. A hands-on course is also required; this prep covers only the written exam.

What's on the exam

ETA FOI
Fiber Optic Transmission, Sources and Receivers
8 key facts
Light and Optical Fiber Theory
8 key facts
Fiber Characteristics and Designations
6 key facts
Fiber Optic Safety
7 key facts
Fiber Optic Cables and Installation
8 key facts
Splicing
7 key facts
Connectors, Cleaning and Inspection
8 key facts
Test Equipment and Link Testing
8 key facts

Each branch is a topic in the official outline. Members see every key fact on the full mind map. Read the free study guide →

How to pass the ETA FOI exam

  • ETA's FOI list names the documents it tests: TIA-568 for component limits, TIA-526-14 for multimode loss testing, TIA-455-57 and IEC 61300-3-35 for end-face inspection, and NEC Article 770 for cable types. Learn the key values from each.
  • You need 75%, so about 57 of 75, in 2 hours. Bring a non-programmable calculator for dBm, numerical aperture and cable-length questions.
  • Know the TIA-568 limits by heart: 0.75 dB per mated connector pair, 0.3 dB per splice, 3.5 and 1.5 dB/km for multimode, and the TIA-598 color code.
  • Sort every loss cause into intrinsic (the fiber itself: core size, mode field, NA mismatch) or extrinsic (the joint: gap, angle, offset, dirt). ETA asks the distinction in both splicing and connector areas.

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Create a free account after the test: your score by topic, a mistakes bank, the complete study notes for the first topic, flashcards and the RCDD Numbers & Formulas Sheet.

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What's in the premium ETA FOI prep

Premium ETA FOI prep is studied one topic at a time. Each step starts with that topic's key notes and flashcard deck, then its own question sets of 25, so you master one topic before you move to the next. When every topic is strong, the 6 full mock exams show you're ready.

3,000practice questions, every answer explained
6full-length mock exams, 75 questions each, timed
800flashcards with spaced repetition, sorted by topic
60comprehensive key notes across 8 topics

Your step-by-step study path

  1. 1
    Fiber Optic Transmission, Sources and Receivers8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Notes free with an account
  2. 2
    Light and Optical Fiber Theory8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  3. 3
    Fiber Characteristics and Designations8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  4. 4
    Fiber Optic Safety8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  5. 5
    Fiber Optic Cables and Installation7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  6. 6
    Splicing7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  7. 7
    Connectors, Cleaning and Inspection7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  8. 8
    Test Equipment and Link Testing7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  9. Final step: 6 full mock exams75 questions each, timed like test day. Pass them, then book your exam.
    Premium
Free with an account

Read the complete ETA FOI study notes for “Fiber Optic Transmission, Sources and Receivers”

Our first full set of comprehensive notes, about 14 minutes of reading: The fiber link · dB and dBm · Light sources · Detectors and receivers, a worked exam example, the traps examiners use and a one-minute recap. Create a free account to read it and see how premium notes work before you decide.

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Study tools included

3,000 practice questions

3,000 exam-style questions per exam, organized topic by topic in sets of 25. Every answer explained, with the rule it comes from.

6 full mock exams

6 full-length timed mock exams per exam, with real question counts and time limits, so test day feels like practice day.

Exam Readiness Score

One 0 to 100 number that tells you when you're ready to book. Reach 80 and you're covered by our Pass Guarantee.

800 flashcards + spaced repetition

800 flashcards per exam, in a deck for each topic, that come back right before you'd forget them. Five minutes a day keeps every number fresh.

60 comprehensive key notes

60 key notes per exam, split across its topics and each explained in full: the concepts, worked exam examples, the traps examiners use and a quick recap. Your first set is free with an account.

Mind maps

See the whole exam on one screen: every topic and the facts under it.

Sample questions with answers

These are the questions in the free test above, with answers. Try the test first. You'll learn more by getting some wrong.

1. A laser launches 0.5 mW into a fiber. Expressed in dBm, what is the launch power?
Answer: -3 dBm. dBm compares power with 1 mW: 10 log (0.5 mW / 1 mW) = 10 x (-0.301) = -3 dBm. Any power below 1 mW is negative in dBm, and halving power always takes off about 3 dB. -6 dBm comes from wrongly using 20 log, which is for voltage ratios, and -30 dBm would be 1 microwatt.
2. A 60 km singlemode link at 1550 nm needs a high bit rate. Why is a DFB laser chosen over an LED source?
Answer: Its narrow spectral width limits chromatic dispersion. A DFB laser emits a single narrow line, so chromatic dispersion spreads pulses far less over long distances, and it couples much more power into a singlemode core. LEDs have a broad spectrum and wide output pattern, use spontaneous emission and are limited to slow, short multimode links.
3. A fiber has a core index of 1.475 and a cladding index of 1.460. Measured from the normal to the core-cladding boundary, what is the critical angle?
Answer: 81.8 degrees. Snell's law gives the critical angle as the inverse sine of (cladding index / core index): 1.460 / 1.475 = 0.9898, and its inverse sine is about 81.8 degrees. Rays striking the boundary at more than this angle from the normal are totally reflected and stay in the core. 8.2 degrees is the complement, measured from the boundary instead of the normal.
4. An old step-index multimode link limits bandwidth badly, while graded-index fiber of the same core size carries far more. What does the graded profile do?
Answer: Makes outer paths faster so all modes arrive closer together. In graded-index fiber the core index falls from the center outward, so light on longer, outer paths travels through lower-index glass and moves faster. Arrival times even out, cutting modal dispersion. The cladding index must always be lower than the core, and a single path is singlemode fiber.
5. An FTTH crew must route fiber around tight corners and staples inside apartments. Which ITU-T fiber recommendation is designed for this?
Answer: G.657 bend-insensitive singlemode. ITU-T G.657 covers bend-loss-insensitive singlemode fiber for access networks and indoor drops; G.657.A fibers are also compatible with G.652 for splicing. G.652 is standard singlemode, and G.655 is built for long-haul DWDM, not tight bends. G.651.1 is multimode.
6. A specification calls for 50/125 µm laser-optimized multimode fiber with an effective modal bandwidth of 2000 MHz·km at 850 nm. Which ISO/IEC designation matches?
Answer: OM3. OM3 is 50 µm laser-optimized fiber with 2000 MHz·km effective modal bandwidth at 850 nm. OM4 raises that to 4700 MHz·km, OM2 is 50 µm fiber at 500 MHz·km, and OM1 is usually 62.5 µm fiber with 200 MHz·km at 850 nm.
7. A connector end looks dark, but the fiber may be carrying 1310 nm laser light. Why is this a particular eye hazard?
Answer: The light is invisible, so nothing triggers a blink. Infrared light at 1310 or 1550 nm cannot be seen, so the eye does not blink or look away and a person can be exposed without knowing. Longer wavelengths carry less energy per photon than red light, so that is not the reason. Never look into a fiber end or connector, and only inspect dark fibers or use a video probe.
8. A riser cable between floors has a metallic armor over the fibers and no current-carrying conductors. Which NEC marking should its jacket carry?
Answer: OFCR. NEC Article 770 types start with OF (optical fiber), then N for nonconductive or C for conductive, then the rating: P for plenum, R for riser, G or none for general purpose. Metallic armor or strength members make the cable conductive, so a riser cable is OFCR. OFNR would be correct only without any metal.
9. A conductive outside plant fiber cable with a metallic armor enters a building. What does NEC Article 770 require for the armor?
Answer: Bond or ground it as close to the point of entrance as practicable. Non-current-carrying metallic members of entering fiber cables must be bonded or grounded as close as practicable to the point of entrance (or interrupted by an insulating joint there), so lightning and power-fault currents are carried off before they reach the inside plant. Leaving the armor floating or bonding only at the rack leaves a shock and fire path inside the building.
10. Two singlemode fibers from different makers have slightly different mode field diameters, and their fusion splice reads very differently on an OTDR from each end. How is this loss factor classed?
Answer: Intrinsic, caused by a difference in the fibers. Intrinsic factors are properties of the fibers themselves: core or mode field diameter, NA, index profile and core concentricity. A mismatch in mode field diameter adds loss even with perfect workmanship and makes OTDR readings differ by direction, so average both directions. Cleave angle, alignment and dirt are extrinsic factors under the installer's control.
11. An inside plant fusion splice is measured at 0.42 dB. What should the installer do under the TIA-568 component limits?
Answer: Remake it, since the limit per splice is 0.3 dB. TIA-568 allows a maximum of 0.3 dB per fusion or mechanical splice, so 0.42 dB fails and the splice should be remade. Most good fusion splices are well under 0.1 dB. The 0.75 dB figure is the limit for a mated connector pair, not a splice.
12. After a dry cleaning, a connector end face viewed under the probe still shows a smear of residue on the cladding. What should the installer do next?
Answer: Clean it wet-to-dry with fiber-grade solvent and inspect again. Oily residue often survives a dry clean, so the next step is a wet-to-dry clean (solvent, then dry wipe) and a fresh inspection against IEC 61300-3-35. Cladding contamination can migrate onto the core when connectors mate. Repolishing is not a cleaning step, and canned air can leave propellant.
13. Why does an APC connector give much lower reflectance than a UPC connector of similar quality?
Answer: Its 8-degree angle sends reflected light out of the core. An angled physical contact (APC) end face is polished at about 8 degrees, so light reflected at the joint hits the core at an angle beyond its acceptance and escapes into the cladding. UPC end faces are domed and reflect straight back along the fiber. Never mate APC with UPC: the gap causes high loss.
14. When measuring multimode link loss with an OLTS, why is the launch jumper wrapped around a mandrel?
Answer: To strip high-order modes so the launch is repeatable. An overfilled launch puts light in high-order modes that are lost in the first few meters, so loss readings come out too high and vary between testers. Five wraps on a mandrel of the specified size, or an encircled flux launch, remove those modes. Dead zones are an OTDR issue, not an OLTS one.
15. A visual fault locator is connected to a fiber at the patch panel. A bright red glow shows through the boot of a jumper behind the panel. What does this indicate?
Answer: A break or tight bend at that point. A VFL injects visible red light that escapes where the fiber is broken, cracked or bent too tightly, so the glow marks the fault location. A healthy jumper shows light only at its far end. A dirty far-end connector would not glow behind the panel, and VFLs work on both fiber types.

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ETA FOI exam FAQ

How many questions are on the ETA FOI exam?

75 questions, with a time limit of 2 hours. Format: closed book; eta allows scratch paper and a non-programmable calculator. foi also requires a special course and hands-on skills exam from an eta-approved school before the written exam, so this prep covers only the written knowledge exam. eta does not publish the item format; our practice uses 4-option single-best-answer questions.

What is the passing score for ETA FOI?

75%.

How much does the ETA FOI exam cost?

US$155 exam fee (ETA list price); the course and hands-on assessment are priced by the school. One free retake within one year of the first session. Certification term 4 years, maintenance required. BICSI fees can change without notice, so confirm on bicsi.org before you apply.

Which languages is the ETA FOI exam offered in?

English. ETA lists Spanish study material and its competency list carries Spanish headings, but it does not say on the exam page whether a Spanish exam is offered; confirm with your Certification Administrator.

Where do I take the ETA FOI exam?

Taken through an ETA-approved school or trainer after its hands-on fiber course; the written exam is proctored by an ETA Certification Administrator, online through Trapeza or on paper.

Is this ETA FOI practice test free?

Yes. The 15-question practice test on this page is free, with an explanation for every answer and no signup. A free account also unlocks the complete study notes for the first topic. The full ETA FOI prep is Premium at $147 a month for this exam.

What's in the premium ETA FOI prep?

3,000 practice questions organized topic by topic (Fiber Optic Transmission, Sources and Receivers: 375; Light and Optical Fiber Theory: 375; Fiber Characteristics and Designations: 375; Fiber Optic Safety: 375; Fiber Optic Cables and Installation: 375; Splicing: 375; Connectors, Cleaning and Inspection: 375; Test Equipment and Link Testing: 375), 6 full-length timed mock exams of 75 questions, 800 flashcards and 60 comprehensive key notes split across all 8 topics, plus a mistakes bank and the Readiness Score.

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Exam details are summarized from the official candidate information available in October 2026. BICSI changes formats and fees, so confirm with ETA International (Electronics Technicians Association, International); program accredited by ICAC to ISO/IEC 17024 before you book. RCDDQuizBank is not affiliated with BICSI or Pearson VUE.

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