I am not an expert and Have never seen any evidince either way but I have my doubts that they will work.
The only ones you see around here anymore are on OLD barns and structures. Dads place (early 1900's farm house) has them on a few of the structures.
[[They are aluminum with and aluminum cable. I have my doubts how good this would be in a lightning strike. I would think that it would just vaporize the cable in an instant.
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Also, If he is putting on a metal roof, what good are the rods sticking up in the air? The whole roof is metal and will be electrified.
Again, this is just my opinion and observations so take it with a grain of salt because I may have no clue at all. But whatever you do, follow the code in the area. Regardless of what you "want" to do, They are always right