N10-009 Question 178
Single answer2.4 Explain important factors of physical installations.A network technician is installing copper Ethernet cabling for several wall-mounted wireless access points in a warehouse. The cable runs must pass through a plenum space above the ceiling that is used for air circulation. The company also wants to reduce fire risk and remain compliant with building codes. Which type of cable jacket should the technician choose for these runs?
- A
CMP-rated plenum cable
- B
CMR-rated riser cable
- C
PVC patch cable
- D
Direct burial cable
Show answer and explanation
Correct answer: A
Explanation
The key physical installation factor in this scenario is the environment through which the cable is routed. Plenum spaces are used for air circulation in many buildings, so cabling installed there must meet stricter fire safety requirements. CMP-rated plenum cable is specifically manufactured to limit smoke and toxic fume emissions during combustion. By contrast, CMR riser cable is for vertical shafts between floors, and direct burial cable is for underground outdoor use. Network+ objectives commonly expect candidates to distinguish between cable types based on installation location, code compliance, and safety. Best practice is to follow local building codes, fire codes, and manufacturer specifications when selecting cable for plenum, riser, or other specialized environments.
- A. Correct.
Correct. CMP-rated plenum cable is designed for installation in plenum spaces, which are areas used for air handling. Its jacket materials are made to produce less smoke and fewer toxic fumes if exposed to fire. This is the appropriate choice for ceiling spaces used for air circulation and is commonly required by building and fire codes.
- B. Incorrect.
Incorrect. CMR-rated riser cable is intended for vertical runs between floors in non-plenum riser shafts. While it has fire-resistance characteristics appropriate for riser applications, it is not the correct choice for a plenum air-handling space. A common misconception is that any fire-rated cable is acceptable everywhere, but plenum spaces require the stricter CMP rating.
- C. Incorrect.
Incorrect. Standard PVC patch cable is typically used for short device-to-jack connections in work areas or equipment rooms, not for in-wall or plenum-space permanent installation. PVC jackets can produce more smoke and toxic fumes during a fire, making them unsuitable for plenum environments.
- D. Incorrect.
Incorrect. Direct burial cable is designed for outdoor underground installation where the cable may be exposed to moisture, soil, and physical stress. That protection does not make it appropriate for indoor plenum use. Someone might choose it because it sounds more rugged, but burial rating and plenum rating address different environmental requirements.