I am a SLF and I have been bashed many times for my comments but there are two posts on this thread that I must criticize.
Metal fatigue occurs over the time, a strike (i.e. with another object) will not have any significant impact on the metal fatigue failure. CI611 went down 20 over years after being poorly repaired...
Faraday cage...it is an ideal conductor therefore does not need to be grounded (actually is otherwise)...one of its function is to protect from lightening strikes... Wikipedia has a quite good description of it...
edit: deSitter gave a accurate description of a Faraday cage
FSLF