Radio & Television Equipment / Antennas

Article 810 is one of the oldest in Chapter 8, dating to the early radio era. It covers radio and television receiving equipment and amateur/transmitting antennas: the antenna itself, the mast, and the lead-in conductor that brings the signal down into the building. Because an outdoor antenna is a prime lightning target and a fall/contact hazard, the article's real focus is grounding and clearance.

It requires an antenna discharge unit (lightning arrester) on the lead-in, a properly sized grounding conductor run as directly as possible to the building's grounding electrode system, and clearances so an antenna or its mast can't fall onto or contact overhead power lines. There are also conductor-size and support rules for the antenna and lead-in. It's aged well because the physics of a metal pole on a roof haven't changed — even as the gear on the end evolved from crystal radios to TV to ham rigs.

When it applies

This covers antennas and their lead-in conductors — a rooftop TV or radio antenna, an amateur station, and the wire running down into the building. The core concern is grounding that mast and lead-in and keeping the whole assembly well clear of power conductors so it never becomes a path to the line or a lightning conduit into the house.

Common mistakes

• Mounting a mast where it could fall onto or contact the service drop.
• Skipping the antenna discharge unit and mast ground, leaving lightning no path but through the building.
• Bonding the antenna ground to a separate rod instead of the building's grounding electrode system.

In the field

When I set an antenna I keep it a full mast-length away from the power lines and ground the mast straight back to the service grounding electrode. An antenna is the highest metal object on the house by design, so if it is not grounded and clear of the lines, you have built a lightning target aimed right at the panel.