How Effective are Lightning Protection Systems?
A great deal of data on lightning protection system performance was collected during the first half of the last century.
Farmers Mutual Insurance Companies of Iowa, studied lightning fire losses from 1905-1912. They determined that the efficiency of lightning rods installed can be estimated at nearly 99%.
Similar statistics were reported by Patrons Mutual Fire Insurance of North Western PA for 1910-1918 during which they paid 414 claims for lightning damage to unprotected buildings and no losses were reported in buildings protected by lightning rods.
In Canada the Ontario Fire Marshall’s inspected lightning protection systems and tracked lightning damage. During 1918-1939 they documented 17,982 lightning related fires of which just 17 involved structures with lightning protection installed. This is an efficiency of 99.999 percent. They also reported that “in no case has a building rodded under the Lightning Rod Act been destroyed by lightning after having been inspected by the Fire Marshall’s office.”
The US Dept of Defense tracks lightning damage at explosives storage facilities, which number in the 1000’s world-wide. In the 82 years from 1918-2000 they report 59 incidents of lightning damage. Of these, 4 were to structures that were equipped with lightning protection.
The FAA tracks lightning damage to its facilities, which are protected by lightning protection systems. FAA documents all lightning strikes within 20 nautical miles of Doppler radar installations. In July, 2000 alone they documented over 250,000 lightning strikes within a 20 nautical mile radius of their sites with just 3 lightning related radar malfunctions. In two Florida locations during this single month, 25,000 and 20,000 cloud to ground strikes were recorded with no equipment failures.