CFOT - Certified Fiber Optic Technician Installation and Hardware Questions and Answers — Questions and Answers
Question 1: An installer is pulling an outside plant (OSP) fiber optic cable with a 0.5-inch diameter through a conduit. To prevent damage, what is the generally accepted minimum bend radius that must be maintained *during* the installation?
- 5 inches (10x the diameter)
- 2.5 inches (5x the diameter)
- 10 inches (20x the diameter) (Correct answer)
- 15 inches (30x the diameter)
Correct answer: 10 inches (20x the diameter)
Industry standards, such as those from the FOA and TIA/EIA, recommend a minimum bend radius of 20 times the cable's outer diameter while the cable is under pulling tension. After installation, when the cable is static, the minimum bend radius is typically relaxed to 10 times the diameter. For a 0.5-inch cable, 20 times the diameter is 10 inches.
Question 2: A technician is installing fiber optic cable in a building's plenum spaces, which are used for environmental air circulation (HVAC). According to the National Electrical Code (NEC) Article 770, which cable rating is required for this application to minimize fire and smoke hazards?
- OFNR (Optical Fiber Nonconductive Riser)
- OFNP (Optical Fiber Nonconductive Plenum) (Correct answer)
- OFCG (Optical Fiber Conductive General-Purpose)
- OFN (Optical Fiber Nonconductive General-Purpose)
Correct answer: OFNP (Optical Fiber Nonconductive Plenum)
The National Electrical Code (NEC) specifies that cables installed in ducts, plenums, and other spaces used for environmental air must be listed as having adequate fire-resistant and low smoke-producing characteristics. For nonconductive optical fiber cables, the OFNP (Plenum) rating is the highest and is required for installation in plenum air spaces to prevent the spread of fire and smoke.
Question 3: During a cable pull, a breakaway swivel is used as a crucial piece of hardware. What is the primary function of this device?
- To prevent the cable from twisting as it is being pulled.
- To allow multiple cables to be pulled simultaneously.
- To automatically lubricate the cable as it enters the conduit.
- To disconnect the pull rope from the cable if the pulling tension exceeds a preset limit. (Correct answer)
Correct answer: To disconnect the pull rope from the cable if the pulling tension exceeds a preset limit.
A breakaway swivel is a safety device designed to protect the fiber optic cable from excessive pulling tension. It is engineered to separate at a predetermined tension level, which is set below the cable's maximum rated pulling force. This ensures the fragile glass fibers inside the cable are not damaged by being stretched or stressed.
Question 4: A technician is preparing to clean fiber optic connectors before mating them. Which of the following is considered a best practice in the 'wet-to-dry' cleaning method?
- Applying compressed air to the end-face immediately after the wet wipe.
- Using a circular scrubbing motion with the wet wipe to remove stubborn contaminants.
- Wiping the connector end-face first on a solvent-dampened area of a lint-free wipe, then moving to a dry area of the same wipe. (Correct answer)
- Dipping the connector directly into a bottle of 99% isopropyl alcohol before wiping it dry.
Correct answer: Wiping the connector end-face first on a solvent-dampened area of a lint-free wipe, then moving to a dry area of the same wipe.
The recommended 'wet-to-dry' or 'combination' cleaning method involves using a lint-free wipe or cassette cleaner with a small amount of approved fiber optic cleaning solvent. The end-face is wiped from the wet area to a dry area in a single, straight motion to dissolve contaminants and then wipe away any residue without leaving streaks or re-contaminating the surface.
Question 5: What is the primary safety concern a technician should be aware of when handling and disposing of bare fiber scraps after stripping and cleaving?
- The scraps can become a source of harmful static electricity.
- The glass shards are sharp and can easily penetrate skin or eyes, causing injury. (Correct answer)
- The scraps can emit residual light that is harmful to the retina.
- The material is a chemical irritant that can cause a rash.
Correct answer: The glass shards are sharp and can easily penetrate skin or eyes, causing injury.
Bare fiber scraps are tiny, sharp shards of glass that are difficult to see. They can easily embed themselves in a technician's skin, causing painful splinters, or worse, get into the eyes. If ingested with food or drink, they can cause internal hemorrhaging. For this reason, all scraps must be disposed of properly in a sealed and clearly labeled sharps container.
Question 6: A technician needs to organize and protect splices and terminations in an outdoor, aerial installation on a utility pole. Which type of hardware is specifically designed for this purpose?
- A rack-mounted patch panel.
- An indoor wall-mount enclosure.
- A pole-mounted fiber optic enclosure. (Correct answer)
- A floor-standing demarcation box.
Correct answer: A pole-mounted fiber optic enclosure.
Pole-mounted fiber optic enclosures are specifically designed to be installed on utility poles for aerial applications. They are built to be weatherproof and durable, protecting the sensitive fiber optic splices and connections from environmental factors like rain, UV radiation, and temperature changes.
CFOT - Certified Fiber Optic Technician Installation and Hardware Questions and Answers
An installer is pulling an outside plant (OSP) fiber optic cable with a 0.5-inch diameter through a conduit.
To prevent damage, what is the generally accepted minimum bend radius that must be maintained *during* the installation?