VDV NEC Code Compliance for Low-Voltage Communications Systems

Question 1

Under the NEC, which communications cable marking is required for installation in a ducted plenum or other space used for environmental air without a raceway?

Accepted Answer

CMP

Answer

CMP (Communications Plenum) cable is listed as having adequate fire-resistant and low-smoke characteristics for air-handling spaces. CMR is for risers, CMG/CM is general purpose, and CMX is limited use.

Question 2

According to the NEC cable substitution hierarchy, which cable may be used in place of CMR riser cable?

Accepted Answer

CMP

Answer

A higher-rated cable can always replace a lower-rated one. CMP is plenum-rated, which sits above riser in the hierarchy, so it can substitute for CMR. CM, CMX, and CMUC are all lower-rated and cannot.

Question 3

What does the NEC require for the accessible portion of abandoned communications cable?

Accepted Answer

It must be removed

Answer

The NEC requires the accessible portion of abandoned cable to be removed, because it adds fuel load and smoke. Cable counts as abandoned if it is not terminated at both ends and not tagged for future use.

Question 4

Which NEC article covers optical fiber cables and raceways?

Accepted Answer

Article 770

Answer

Article 770 covers optical fiber cables and raceways. Article 820 covers CATV/coaxial systems, Article 250 covers grounding and bonding, and Article 517 covers health care facilities.

Question 5

A technician wants to zip-tie Category 6 cables to the outside of an electrical conduit to support them across a ceiling. What does the NEC say?

Accepted Answer

It is not allowed; raceways may not be used as a means of support for communications cables

Answer

The NEC prohibits strapping, taping, or attaching communications cables to the exterior of a conduit or other raceway as a means of support. The cables need their own approved supports, such as J-hooks or cable tray.

(VDV) Voice Data Video Technician Certified Practice Test

(VDV) Voice Data Video Technician Certified Practice Test

VDV NEC Code Compliance for Low-Voltage Communications Systems