Speaking on Deep Background, the Press Secretary whispered:
You most emphatically do NOT want copper going across your parking lot.
Besides the danger from lightning strikes and other electrostatic discharges
you run the risk of ground potentials differing significantly. You could
wind up with a significant amount of current flowing across the coax just to
balance building grounds. (This is why telcos insist on a single ground
point and have that point connected to an array of ground rods driven deep
in the ground.)
Fiber is Your Friend [tm].
Ground loops and potential differences will not only have you
ripping your hair out, but you stand to lose DS-3 ports. Now
some guy told me that such costs a bit more than the RS-232 &
Ethernet ports I regularly see die, but that's likely just a rumor.