Communications Circuits and Community Antenna/Broadband Systems (NEC Articles 800 and 820)
What this domain tests
Article 800 covers communications circuits such as telephone and data; Article 820 covers community antenna and broadband/CATV systems. The exam tests cable substitution, separation from power, primary protection, and grounding and bonding of incoming metallic communications and coaxial cables.
Core rules
- Communications cable markings: CM general, CMR riser, CMP plenum. CATV cable uses similar CATV, CATVR, and CATVP designations.
- Do not substitute a lower-rated cable for the environment. Plenum spaces require CMP or CATVP; risers require CMR or CATVR.
- Communications circuits must be separated from power conductors per Article 800 and 820 unless a barrier or listed method permits.
- Incoming communications and CATV cables with metallic members generally require primary protection and bonding to the building grounding electrode system. The shield of coaxial cable is bonded, not left floating.
- Grounding blocks and protectors must be listed and accessible.
Worked example
A Cat 6 cable is routed through a return-air plenum above a ceiling. CM cable is not acceptable; use CMP. A coaxial CATV drop enters the building and connects to a splitter. The coaxial shield must be bonded to the grounding electrode system through a listed grounding block, and the cable must maintain separation from power.
Traps
- Using CM cable in a plenum because it is just data.
- Sharing a raceway with power without a barrier.
- Leaving the CATV shield unbonded.
- Confusing Article 800 data cable with Article 725 Class 2 cable.