VDV Cabling Infrastructure 2 — Questions and Answers
Question 1: What is the maximum pulling tension allowed for a 4-pair UTP Cat6 cable during installation?
- 25 lbf (Correct answer)
- 50 lbf
- 110 lbf
- 200 lbf
Correct answer: 25 lbf
ANSI/TIA-568 specifies a maximum pulling tension of 25 lbf (110 N) for 4-pair UTP horizontal cabling to avoid stretching or damaging the pairs.
Question 2: Which conduit fill percentage is recommended by NEC for three or more conductors in a single conduit?
- 53%
- 40%
- 31% (Correct answer)
- 60%
Correct answer: 31%
NEC Chapter 9 Table 1 limits conduit fill to 40% for two conductors and 31% for three or more conductors to allow heat dissipation and ease future pulls.
Question 3: A technician is installing cable in a plenum space. Which cable jacket rating is required?
- CMR
- CM
- CMP (Correct answer)
- CMG
Correct answer: CMP
CMP (Communications Plenum) rated cable is required in air-handling spaces because it produces minimal smoke and flame spread when burned.
Question 4: What minimum bend radius must be maintained for a Cat6A UTP cable during installation?
- 4 times the cable diameter
- 6 times the cable diameter
- 8 times the cable diameter (Correct answer)
- 10 times the cable diameter
Correct answer: 8 times the cable diameter
TIA-568-C.2 requires a minimum bend radius of 8 times the cable outer diameter for Cat6A UTP during and after installation to preserve signal integrity.
Question 5: In a structured cabling system, what is the purpose of the Intermediate Distribution Frame (IDF)?
- To house the main carrier demarcation equipment
- To serve as a sub-distribution point connecting floor-level equipment to the MDF (Correct answer)
- To terminate backbone fiber between buildings
- To provide power over Ethernet to endpoints
Correct answer: To serve as a sub-distribution point connecting floor-level equipment to the MDF
The IDF (also called a Telecommunications Room) aggregates horizontal cabling from work area outlets on a floor and connects back to the MDF via backbone cabling.
Question 6: When installing a cable tray, what is the standard maximum fill capacity by cross-sectional area according to NEMA VE-1?
- 50% (Correct answer)
- 40%
- 75%
- 60%
Correct answer: 50%
NEMA VE-1 specifies that cable trays should not exceed 50% fill of their cross-sectional area to allow airflow, ease maintenance, and future cable additions.
Question 7: Which type of grounding conductor is used to bond telecommunications equipment racks to the building's ground system per TIA-607?
- Telecommunications Main Grounding Busbar (TMGB)
- Equipment Bonding Conductor (EBC)
- Telecommunications Bonding Backbone (TBB) (Correct answer)
- Ground Fault Circuit Interrupter (GFCI)
Correct answer: Telecommunications Bonding Backbone (TBB)
The Telecommunications Bonding Backbone (TBB) connects Telecommunications Grounding Busbars (TGB) in each telecom room back to the TMGB, forming the main grounding path.
VDV Cabling Infrastructure 2
What is the maximum pulling tension allowed for a 4-pair UTP Cat6 cable during installation?