If you really want to know, get in touch with Dr. Uman at the University of Florida lightning research lab. ECE-UF Dr. Martin Uman
He is pretty much the expert in lightning protection engineering in the world from what I understand, though I have never dealt with him directly.
Another expert is Roger R. Block, co-founder of PolyPhaser Corporation, who has done a great deal of work protecting very expensive and one-off gear for the military and three letter initial companies inside the beltway. Extensive testing and validation and his works are available on the net. He has retired for the most part, but his devices and protection plans are second to none.