I remember hearing a story about some cows sheltering under
a tree during a thunderstorm. Lightning struck the tree and
the cows facing towards or away from the tree were electrocuted
while those broadside to the tree were not. The explanation was
that, as the charge dissipated through the ground, the cows
facing toward or away from the tree had their front and rear
hooves on ground of much different potentials. Those broadside
has much less difference between left and right side hooves.
I would think that a wire connected to a ground rod under these
conditions would behave much the same. If the equipment in the
shack had no other current path, nothing would happen as they
would all rise to the same potential simultaneously. However,
if there was another path to ground, it could have a vastly
different potential and sparks would fly.
Ask me sometime about the Great Lightning Disaster at the LORAN
station I commanded. It was caused by the Coast Guard insistance
on separate ground systems for the transmitter and timing equipment.