The Dangers of Lightning
Every year, lightning causes billions of dollars in damage to homes and businesses. Deaths and property losses from lightning strikes exceed those caused by floods, tornadoes, and hurricanes combined. Lightning is also the leading cause of rural and suburban fires.
Computers and electronic equipment in homes and businesses are especially at risk, as lightning can destroy semiconductor devices, printed circuit boards, magnet-based hard disks, and program logic controllers.
Where Lightning Strikes
Lightning reaches the earth through the path of least resistance. Without a lightning protection system, a building is most likely to carry the electricity through its wiring or plumbing, or through the structure itself. None of these can withstand such a high current.
Even without a direct lightning strike, a powerful electrical surge can be carried through the ground to buried cables, metal wires, and reinforcement bars in walls and floors.
With a direct strike on a building, even a small amount of moisture in construction materials will become superheated steam that can explode concrete, lumber, or drywall.