Community Antenna TV & Radio Distribution (Coax)

Article 820 governs coaxial cable distribution — community antenna television (CATV) and the coax that carries cable TV and cable internet into premises. Coax is unusual because the signal rides the center conductor while the outer shield is metallic and grounded; the article's central concern is bonding and grounding that shield correctly.

At the point of entrance, the coax shield must be bonded to the building's grounding electrode system with a listed grounding block and a short, direct grounding conductor, so surge energy from lightning or a downed power line drains to earth rather than into the home. The article also covers coax cable listings (CATV, CATVR, CATVP for general, riser, plenum), separation from power conductors, support, and abandoned-cable removal. It leans heavily on Article 800's common rules for the grounding methods themselves.

When it applies

Article 820 covers coaxial cable systems, the CATV and cable-internet coax coming into homes and buildings. Its central concern is bonding the cable's metallic shield to the building grounding system and guarding against surge and lightning riding in on that line.

Common mistakes

• Skipping the ground block or bonding the shield to a stray ground rod instead of the building's grounding electrode system.
• Running the bonding conductor long and looping, which raises impedance and slows surge diversion.
• Leaving the coax entrance ungrounded because the picture looks fine, ignoring the lightning path.

In the field

On a cable-internet install I bonded the coax ground block straight to the home's grounding electrode system with a short, direct conductor, not to a random rod by the wall. That common bond keeps a surge on the line and the building's power ground at the same potential, so lightning energy has a fast route to earth instead of arcing across the customer's equipment. A five-minute bond saves a modem and maybe a fire.