What is a Ground Block?

Paul Scott

A ground block is a fitting designed to effectively ground coaxial cables from satellite dishes and external antennas. This ground connection is an essential protective measure to prevent damage to satellite dishes and television sets from lightning strikes. A ground block is typically made of brass and consists of one or more built in dual coaxial fittings, ground wire connection points, and mounting lugs. The block serves to combine the ground elements of the dish cable, dish assembly, TV set, and transfer cable into a single well grounded unit. The dual coaxial fitting allows a second coaxial transfer cable to be run from the ground block to the TV without any signal loss.

Lightning strikes cause frequent damage to satellite dishes.
Lightning strikes cause frequent damage to satellite dishes.

Transient electrical surges caused by lightning strikes cause hundreds of millions of dollars worth of damage to property and equipment each year. Ensuring the ground circuits in a home are correctly installed and functional can go a long way to preventing this sort of damage. One piece of household equipment which is damaged by lightning more often than most is the satellite dish and/or TV system. The installation of a ground block on the dish cable is one of the most effective ways of tying the dish, cable, and TV system into the ground circuit and avoiding lightning damage.

Ground blocks are used to ground coaxial cables from satellite dishes.
Ground blocks are used to ground coaxial cables from satellite dishes.

A ground block is basically a conductive transfer device mounted on the building near the coaxial cable entry which creates a grounded connection for the satellite dish, cables, and TV. These devices are made of a conductive material such as brass and have one or more pairs of back-to-back coaxial fittings built into them. A coaxial cable grounds through its protective metal sheath which is held captive under the outside screw down part of the plug. When the dish cable is screwed into the ground block coaxial fitting, a good electrical connection is formed between the cable and the ground block.

The device is also equipped with several ground wire lugs. The messenger or ground cable from the dish is connected to one of these lugs. A suitable ground cable is then run from another of the ground wire lugs to the nearest building grounding point. This arrangement effectively creates a good electrical connection between the dish, its coaxial cable, and the building's grounding system.

To complete the installation, a transfer cable is connected to the opposite side of the fitting carrying the dish cable and run to the TV set. The ground block will then also create a solid ground point for the transfer cable and the TV antenna input. When connecting the coaxial cables, messenger cable and ground link, it is good practice to form a drip-loop in each which hangs down and diverts moisture away from the connections. Silicone grease can also be applied to the ground link and messenger cables bared ends to prevent corrosion from compromising the ground continuity.

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