DCI Copper Installation 4 — Questions and Answers
Question 1: What does a 'split pair' wiring error show on a cable tester wire map?
- Open circuit on one conductor
- Correct wire map but failed NEXT test (Correct answer)
- Crossed pairs between two different pairs
- Short circuit between pin 1 and pin 2
Correct answer: Correct wire map but failed NEXT test
A split pair shows a correct wire map continuity but catastrophically fails NEXT because the pair twist is broken by mixing conductors from different pairs.
Question 2: When using a 110-type punchdown block, what type of punchdown tool blade is required?
- Krone blade
- 66-type blade
- 110-type blade (Correct answer)
- BIX blade
Correct answer: 110-type blade
A 110-type blade is specifically designed for 110 connecting blocks and cuts the conductor flush while seating it into the IDC contact.
Question 3: What is the recommended maximum gap between cable support fasteners (J-hooks or staples) on a horizontal cable run?
- Every 12 inches
- Every 24 inches
- Every 4 to 5 feet (Correct answer)
- Every 10 feet
Correct answer: Every 4 to 5 feet
BICSI and TIA guidelines recommend supporting horizontal cable every 4 to 5 feet (1.2–1.5 meters) to prevent sagging and cable damage.
Question 4: What is 'DC loop resistance' in a copper cable?
- The resistance of the shield to ground
- The total resistance of both conductors in a pair measured as a loop (Correct answer)
- The resistance between the two cable ends at 60 Hz
- The impedance of the cable at DC frequencies
Correct answer: The total resistance of both conductors in a pair measured as a loop
DC loop resistance is measured by connecting the two conductors of a pair at one end and measuring the total resistance of the complete loop at the other end.
Question 5: Which standard defines the telecommunications pathways and spaces for commercial buildings?
- ANSI/TIA-568
- ANSI/TIA-569 (Correct answer)
- ANSI/TIA-606
- ANSI/TIA-607
Correct answer: ANSI/TIA-569
ANSI/TIA-569 (Commercial Building Standard for Telecommunications Pathways and Spaces) covers conduits, cable trays, and equipment room design.
Question 6: What is the purpose of the blue cable on a T568B-wired horizontal run?
- It is used for voice (POTS) only in T568B wiring
- It carries the pair 2 signals used for 10BASE-T transmit
- It is part of pair 1 designated for voice or PoE (Correct answer)
- It is the earth ground conductor
Correct answer: It is part of pair 1 designated for voice or PoE
In T568B, the Blue/White-Blue pair is pair 1 (pins 4 and 5) and is traditionally used for analog voice or the spare pair in 10/100BASE-T.
Question 7: A cable is labeled '23 AWG, UTP, Cat6, CMR.' What does 'CMR' indicate?
- Copper Metal Rated — suitable for outdoor use
- Communications Multipurpose Riser — rated for vertical runs in riser shafts (Correct answer)
- Conduit and Metallic Raceway approved
- Commercial Moisture Resistant jacket
Correct answer: Communications Multipurpose Riser — rated for vertical runs in riser shafts
CMR (Communications Multipurpose Riser) is an NEC cable jacket rating suitable for use in vertical riser shafts between floors of a building.
DCI Copper Installation 4
What does a 'split pair' wiring error show on a cable tester wire map?