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Antenna Grounding - Coax cable grounding : Antenna Hookup digital and analog TV
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Antenna Grounding: Outside antennas for TV - Lightning Protection
ANTENNA, CATV GROUNDING

Grounding outside TV antennas and cable TV coaxial cables:

Outside TV antennas should be grounded to prevent damage to your equipment from static electricity particularly during a thunderstorm. Lightning travels mostly in a straight line with a final goal of hitting the earth and it will follow the path of least resistance, so any sags or bends in the ground wire is a place where the lightning can "jump" out.

Keep in mind that in the rare event you sustain a direct lightning strike, nothing is guaranteed, even with a ground. There is nothing you can do to 100% prevent damage to your gear if you get a direct lightning strike. The good news is a direct lightning strike is very rare. Most likely you will never get a direct strike. The antenna mast itself must be grounded and the coax cable also must be grounded. The coax cable, usually RG-6, needs to be grounded so a surge in current does not enter your equipment and destroy expensive components like a digital TV set.

The goal is to prevent a buildup of static electricity in the first place and to try to keep damage from occuring to sensitive diodes and circuits in your electronic components. A grounding block is used to ground the outside antenna. You will want to try to keep the static electricity outside your house. Never run the wires inside your house. Run the wires straight from the antenna mast to ground and keep the length as short and straight as possible. Ground is defined as a rod driven 8 ft. into the earth. If hard soil prevents driving a metal rod 8 ft. deep, then dig a trench 8 ft. long parallel to the earth's surface and down into the earth as far as the soil will allow you to dig.

The United States National Electrical Code (NEC) specifies that coaxial cable that is exposed to lightning shall be connected to the grounding system of the building as close to the point of cable entry as possible.

The grounding rod should be near the mast. With an antenna, you can ground the mast, the boom, the dish, the director and reflectors of the antenna by contact metal bonding to a ground wire run directly into the earth via a deep ground rod, but you cannot directly ground the driven element or active element of the antenna. All you can do is make a reasonable attempt at grounding it via a coaxial grounding block to reduce static charge buildup and reduce probability of a lightning hit.





Grounding Block

The grounding block is a device designed to bleed off high voltage spikes that reach dangerous levels that would damage your receiving equipment. They don't directly short out the center conductor to the ground because this would kill the signal but rather allow a small gap that will on a continuous basis bleed off the building static charge before it reaches dangerous levels to your equipment. Using a grounding block located just before the coaxial feed wire enters your building is what is recommended to effectively reduce the probability of small static electricity damage to your receiver. It will NOT protect against a direct lightning hit. Both the grounding block on the coaxial cable (75 ohm) and a direct ground wire to the mast of the antenna should be used.



GROUNDING BLOCK - Single Coaxial with F-connectors

Attach a coax grounding block, available at any Radio Shack or online, to a point near where the cable enters the building. Connect one length of your coax antenna cable between the block and antenna and a second length between the other end of the block and your receiver (TV). Then run a length of grounding wire from the block to a grounding rod.



Diagram of Antenna grounding

Grounding points need to be a true earth ground (defined as a length of pipe driven eight feet or more into the ground).

You also need to ground the antenna itself by running another length of grounding wire between the antenna and ground point. Your antenna itself may have special instructions for grounding; if so, be sure to follow them. If you're not sure you've grounded your antenna correctly, consult a professional experienced in installing antennas or the manufacturer of your antenna itself.

It is not recommended to use water pipes, copper or not, because the pipe may not be a true ground. Sometimes a repair has been done to the pipes and instead of copper, PVC (plastic) was used.

Mount the grounding block as close as possible to where the 75 ohm coaxial cable downlead enters the house. The ground wires for both the mast and the downlead should be copper wire, number eight (8) or larger. The downlead wire from the antenna to the grounding block and the mast ground wire should be secured to the house spaced from four (4) to six (6) feet apart.

Grounding the Antenna Mast





The NEC requires that the antenna mast and mount be grounded directly. No splices or connections are allowed in the ground wire between the mast and the ground rod.

First, attach one end of a No. 8 or No. 10 copper ground wire to the antenna mast. One of the bolts on the mount can be used as a fastening point. Masts that are painted or coated must have their coating scraped off around the area where they contact the mount. This will ensure an electrical connection between the mast and the mount. It is vital to get a good, solid connection.




(Once the mast is attached to the mount, any scraped off portion that is exposed should be recoated with paint or other sealant.)

Next, run the ground wire to earth ground as directly as possible. Standard wire staples can be used to secure the ground wire against the side of the house. Avoid making 90° or sharper turns with the ground wire. A lightning charge has difficulty making such a turn and therefore may discharge into the house. Make ground wire bends as smooth and as gradual as possible.

The ground wire must be connected to a ground rod. Water pipes or plumbing fixtures are not acceptable. A good copper-coated steel ground rod driven at least 3 to 8 feet into the ground is required. Special clamps that provide a solid connection between the ground wire and ground rod should be used.


Ground Rod - copper coated steel rod



Grounding the Transmission Line

It is not just the height of an antenna that makes it susceptible to lightning strikes. Antennas and transmission line can accumulate static electrical charges that also increase the chances of lightning hitting an installation. To properly “draw off” this static electricity, a small device known as an antenna discharge unit must be included on the installation.

The antenna discharge unit (also called a “lightning arrestor”) is connected to the transmission line at a point close to where the transmission line enters the house. One end of a ground wire is attached to the discharge unit. The other end of the wire is connected directly to the ground rod.

An antenna installation is not adequately grounded unless both a mast ground and an antenna discharge unit are installed correctly.




WARNING: Please take proper safety precautions if you decide to install your antenna on the roof or another potentially dangerous location. Consult a professional for help installing a rooftop antenna. Do not try to install an antenna on a wet roof or one covered with ice or snow. Always have someone else with you whenever you climb up on a roof. If you fall, they can help or call for help.

Make sure all of your gear is plugged into a quality surge protector, preferably one that's guaranteed for at least the amount of your equipment cost.



If you know a storm is approaching, it is a good idea to disconnect the coaxial cable from the TV set.

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