Lightning down conductors

Down Conductors. When lightning strikes an air terminal... 

Masonry stacks should be connected to ground with at least two conductors on opposite sides of the stack and connected individually to the lightning rod. The down conductors should be interconnected at intervals not exceeding 100 feet. All metal structures, platforms, ladders, water pipes, etc. located within the area should be connected to the lightning protection system. 

Materials that are poor conductors of electricity are generally considered nonmetals. One important use of nonmetals, in fact, is the capability to insulate against current flow. Earths atmosphere is composed of nonmetallic elements, but lightning can break down the electron bonds and allow huge voltages to make their way to the ground. Water in its pure form is nonmetallic, though it almost always contains impurities called electrolytes that allow for an electric field. 

Fig. 6 shows a simplified version of the lightning protection zone model. The reactor building is protected against direct lightning strike by an external system with air terminal rods and horizontal conductors, down leads and a equipotential bonding ring type. This equipment passes lightning strikes down into the earth. In conjunction with the external... 

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