ADTRAN 25 manual Lightning Protection

INSTALLATION

metal frame of the building, a concrete encased ground, or a ground ring. If these grounds are not available, the water pipe ground can be supplemented by one of the following types of grounds.

●Metal underground gas piping system—an electrically continuous metal underground gas piping system that is uninterrupted with insulating sections or joints and without an outer nonconductive coating.

●Other local metal underground systems or structures—local underground structures such as tanks and piping systems.

●Rod and pipe electrodes— a 5/8-inch (solid rod) or 3/4-inch (conduit or pipe) electrode driven to a minimum depth of 8 feet.

●Plate electrode—expose a minimum of 2 square feet of metallic surface to the exterior soil.

3.Concrete encased ground—defined to be an electrode, consisting of at least 20 feet of one or more steel reinforcing rods at least 1/2 inch in diameter, or 20 feet of bare copper conductor not smaller than #4 AWG encased in 2 inches of concrete. This electrode must be located within and near the bottom of a concrete foundation or footing that is in direct contact with the earth.

4.Ground ring consisting of at least 20 feet of bare copper conductor not smaller than #2 AWG encircling the building. The ground ring must be in direct contact with the earth and buried at least 2.5 feet below the earth’s s u r f a c e .

Lightning Protection

System 25’s lightning protection plan involves five distinct but interdependent items required at every installation:

●Primary protection in the form of voltage limiters (typically carbon blocks or gas tubes) on all pairs that leave the building, whether aerial or buried. These devices bypass surges to approved building ground and limit potential differences between T/R pairs and building ground to less than 1500 volts.

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