C7 CATV, Satellite & Antenna Systems (NEC Articles 810 & 820)

Question 1

NEC Article 820 governs the installation of which type of low voltage system?

Accepted Answer

Community antenna television (CATV) and coaxial cable systems

Answer

NEC Article 820 specifically covers Community Antenna Television (CATV) and radio distribution systems using coaxial cable. Data cabling is covered under Article 800, fiber under Article 770, and remote-control circuits under Article 725.

Question 2

Per NEC Article 820, where must the coaxial cable from a CATV service be grounded when it enters a building?

Accepted Answer

At the point of entry to the building, as close as practicable

Answer

NEC 820.93 requires that the outer conductive shield of the coaxial cable be grounded as close as practicable to the point where the cable enters the building. This protects against lightning surges and static buildup traveling on the cable shield from outdoors.

Question 3

When installing a satellite dish on a residential rooftop, per NEC Article 810, the mast and mounting structure must be:

Accepted Answer

Bonded to the building's grounding electrode system

Answer

NEC Article 810.21 requires the antenna mast and associated equipment to be bonded to the building's grounding electrode system. Using an isolated separate rod is a code violation — all grounding electrodes must be bonded together to prevent dangerous voltage differences during a lightning event.

Question 4

A CATV distribution system uses a two-way splitter at the point of entry to serve two TVs. Each two-way splitter introduces approximately how much signal loss?

Accepted Answer

3.5 dB

Answer

A two-way splitter introduces approximately 3.5 dB of insertion loss (theoretically 3 dB for the power split plus ~0.5 dB of passive loss). This loss accumulates with each additional splitter, which is why signal levels must be calculated for CATV distribution systems to ensure adequate signal strength at the last outlet.

Question 5

Which coaxial cable type is the current standard recommended for CATV, satellite, and over-the-air antenna installations in new residential construction?

Accepted Answer

RG-6 (75 ohm)

Answer

RG-6 (75-ohm) is the current standard for residential CATV, satellite, and antenna wiring. It has a larger center conductor and thicker dielectric than RG-59, resulting in lower signal loss especially at higher frequencies (satellite bands). RG-8 and RG-58 are 50-ohm cables used in radio/RF applications, not CATV.

(C7) California C7 Low Voltage Systems Contractor Certification Practice Test

(C7) California C7 Low Voltage Systems Contractor Certification Practice Test

C7 CATV, Satellite & Antenna Systems (NEC Articles 810 & 820)