A lightning strike causes a significant amount of damage to nearly anything it hits. Most people have seen pictures or videos of the damage that is caused in the area that the strike happens, generally resulting in explosion and fire, and most times resulting in the destruction of the thing that is struck. In order to prevent lightning from striking structures that are known to be vulnerable due to their physical makeup and positioning, precautionary measures like the installation of nearby lightning rods and overhead shields is usually the consideration. The main idea is to divert the lightning away from the structure that would be damaged by the strike, and to a different area that would see less costly damage. Lightning always travels to earth, so the methods of diverting lightning strikes involve positioning these protection mechanisms away from expensive equipment and connected to the ground. Hopefully, the lightning will be attracted to them instead of the more expensive structure in the event of bad weather.
One issue that most industrial facilities face is that lightning striking is not the only form of damage that is usually sustained. A massive power surge follows the lightning strike as electricity from the strike is distributed along the paths of least residence. This surge of power can couple into nearby structures and lines or cables, and ultimately travel along those paths until it is either stopped or diverted. This means that far more electricity than can be safely managed will move from the point of strike along any path that it can, and any components or equipment that are chained together either through attachment points in a structure or through data or power lines are now vulnerable. The power surge will damage the circuitry of any computerized equipment, and potentially create an explosion or fire within it. Because that component is connected to additional components through cables and wires, the surge is allowed to continue to that next piece of equipment and do the same. Because of this vulnerability, damage is not isolated to the strike point and can be found to have negative effects on components that are not even in the same structure where the strike took place. This causes damage costs and levels to be significantly higher than otherwise would be found.
The installation of surge protection devices in addition to lightning protection is necessary to avoid this type of additional damage, or to at least minimize it. Surge protection devices installed along the potential electrical paths from component to component can create a gap where the flow cannot continue, protecting any equipment beyond it. While there is no such thing as a perfect system that can prevent all types of damage, we must expect that certain types of installations will eventually be struck by lightning and prevent against the damage that we know will occur. Installation of surge protection devices redundantly and constructed from the most robust materials is the most effective way to minimize damage.