I have just started reading NFPA 780, an American National Standard for
the Installation of Lightning Protection Systems (2011).
It uses SI units primarily and non-SI units secondarily, as stated in
Clause 1.6. The SI units take precedence as the standard values. I did
notice one drawing where the dimension line values are given in feet,
but conversion factors are provided at the base of that diagram.
I also received LPI-175 Standard of Practice for the
Design-Installation-inspection of Lightning Protection Systems (2008)
published by the Lightning Protection Institute. This document uses
non-SI values primarily with SI values secondarily. It's purpose relates
to certification of lightning protection individuals, companies, and
systems.
Jim
--
James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030
(C) 931.212.0267
(H) 931.657.3107
(F) 931.657.3108
