RCDD (RCDD): Case Studies and Concepts 5 — Questions and Answers
Question 1: A case study describes an existing building where horizontal cable runs must pass through a 2-hour fire-rated wall. What is the correct approach per applicable codes?
- Use plenum-rated cable, which is exempt from firestop requirements
- Install all cables in a single conduit and apply a UL-listed firestop system around the conduit (Correct answer)
- Route cables through HVAC ductwork to avoid penetrating the fire wall
- Apply fire-rated paint on cables within 1 m of the penetration
Correct answer: Install all cables in a single conduit and apply a UL-listed firestop system around the conduit
All penetrations through fire-rated assemblies must be sealed with UL-listed firestop systems; plenum rating does not exempt cables from this requirement.
Question 2: An RCDD is designing a 400 m backbone fiber run between two campus buildings. Multimode fiber is proposed. Per ANSI/TIA-568.3-D, which multimode fiber type supports 10GBASE-SR at this distance?
- OM1
- OM2
- OM3
- OM4 (Correct answer)
Correct answer: OM4
OM4 multimode fiber supports 10GBASE-SR at up to 400 m, whereas OM3 is limited to 300 m at 10 Gbps.
Question 3: During a site survey for a new telecommunications room, the RCDD discovers the proposed space has a ceiling height of 2.1 m. Per ANSI/TIA-569-D, what action should be taken?
- Proceed with design since 2.1 m meets the minimum 2.0 m requirement
- Request that the ceiling height be raised to the minimum 2.4 m (Correct answer)
- Install low-profile 2-post racks to accommodate the reduced height
- Document the deviation and obtain an authority having jurisdiction variance
Correct answer: Request that the ceiling height be raised to the minimum 2.4 m
ANSI/TIA-569-D specifies a minimum ceiling height of 2.4 m (8 ft) for telecommunications rooms, so 2.1 m is non-compliant.
Question 4: A government building requires a telecommunications infrastructure that supports classified and unclassified networks. The RCDD must ensure physical separation between the two networks. What concept governs this requirement?
- Network segmentation via VLAN tagging on shared physical media
- Physical separation (air gap) with separate dedicated cabling systems for each classification level (Correct answer)
- Using shielded cabling for classified data and UTP for unclassified data on the same runs
- Encrypting classified traffic over shared infrastructure with AES-256
Correct answer: Physical separation (air gap) with separate dedicated cabling systems for each classification level
Classified government networks typically require a physical air gap with completely separate, dedicated cabling systems per NIST and DISA requirements.
Question 5: An RCDD is reviewing the administration and labeling plan for a 500-outlet installation. Per ANSI/TIA-606-C, which identifier is required on every horizontal link?
- A sequential numeric ID unique within the building
- An identifier that includes the TR designation and a unique link number within that TR (Correct answer)
- The cable manufacturer's part number and batch code
- The installer's initials and installation date
Correct answer: An identifier that includes the TR designation and a unique link number within that TR
TIA-606-C requires each horizontal link to have an identifier that includes the serving telecommunications room identifier and a unique link number within that space.
Question 6: In a case study, a large law firm requests that all server room access be logged with timestamps. The RCDD is designing the physical access control cabling. Which cabling type is most appropriate for connecting door readers to access control panels in an IDF?
- CAT 6A UTP horizontal cable
- 22 AWG shielded multi-conductor cable (Correct answer)
- RG-6 coaxial cable
- Single-mode fiber with media converters
Correct answer: 22 AWG shielded multi-conductor cable
Access control readers and control panels are typically connected with 22 AWG shielded multi-conductor cable per industry practice and manufacturer requirements.
Question 7: A hospital RCDD case study requires designing a redundant pathway for life-safety systems between the equipment room and the main nursing station. What is the minimum number of diverse pathways required?
- One pathway with conduit fill limited to 40%
- Two completely separate and physically diverse pathways (Correct answer)
- Three pathways with one serving as a cold standby
- One pathway with a redundant cable installed alongside
Correct answer: Two completely separate and physically diverse pathways
Life-safety and mission-critical systems require two physically diverse pathways so that a single physical event (fire, construction accident) cannot sever all connectivity.
RCDD (RCDD): Case Studies and Concepts 5
A case study describes an existing building where horizontal cable runs must pass through a 2-hour fire-rated wall.
What is the correct approach per applicable codes?