VDV Cabling Standards 3 — Questions and Answers
Question 1: In the TIA-568 T568A and T568B wiring schemes, which pair is reversed between the two standards?
- Pairs 2 and 3 (Correct answer)
- Pairs 1 and 4
- Pairs 2 and 4
- Pairs 1 and 3
Correct answer: Pairs 2 and 3
T568A and T568B differ only in the position of pairs 2 (orange) and 3 (green), which are swapped between the two standards.
Question 2: What testing parameter measures the unwanted signal coupling from one pair to another at the near end of a cable?
- Return Loss
- NEXT (Correct answer)
- ELFEXT
- Insertion Loss
Correct answer: NEXT
NEXT (Near-End Crosstalk) measures electromagnetic coupling between pairs at the end closest to the signal source.
Question 3: According to TIA-569, what is the maximum fill ratio for conduit carrying communications cables?
- 25%
- 40%
- 53% (Correct answer)
- 60%
Correct answer: 53%
TIA-569 allows a maximum 53% fill ratio for conduit to allow cable movement and heat dissipation.
Question 4: Which fiber optic cable type is specified for backbone runs exceeding 300 meters per TIA-568?
- OM1 multimode
- OM3 multimode
- OS1 singlemode (Correct answer)
- OM4 multimode
Correct answer: OS1 singlemode
OS1 (or OS2) singlemode fiber supports backbone distances far exceeding 300 meters, up to kilometers depending on the application.
Question 5: What does 'ANSI/TIA-606' specifically govern in a structured cabling system?
- Grounding and bonding
- Administration and labeling (Correct answer)
- Pathways and spaces
- Optical fiber splicing
Correct answer: Administration and labeling
TIA-606 covers the administration standard for telecommunications infrastructure, including labeling, records, and documentation.
Question 6: When testing insertion loss on a Cat6 link, which condition causes the measurement to fail?
- Cable length shorter than 15 meters
- Excessive attenuation due to long runs or high ambient temperature (Correct answer)
- Cable installed with T568A instead of T568B
- Using solid conductor patch cords
Correct answer: Excessive attenuation due to long runs or high ambient temperature
Insertion loss (attenuation) increases with cable length and temperature; exceeding the TIA-568 limit causes a test failure.
Question 7: Which standard defines the optical fiber connector loss budget for multimode horizontal links?
- TIA-568-C.0
- TIA-526-14
- TIA-568-C.3 (Correct answer)
- ANSI/TIA-598
Correct answer: TIA-568-C.3
TIA-568-C.3 specifies optical fiber cabling components and performance standards including connector and link loss budgets.
VDV Cabling Standards 3
In the TIA-568 T568A and T568B wiring schemes, which pair is reversed between the two standards?