The scenario I do worry about is linking 2 adjacent buildings via FTP cable in case the the buildings grounds end up a different potential - I'd imagine there are cases where a significant shield current could be flowing.
Naturally one would likely avoid that entirely as a by-product linking in fibre anyway.
This brings back bad memories of being at school in the 1980s. We had a bunch of BBCs running on Econet - bus topology, two twisted pairs (or a twisted quad, depending on the generation of the cable) with a foil shield and drain wire. Econet has a clock pair and a data pair using CSMA/CD.
It was far from unusual for a thunderstorm to knock out all the line driver chips on a segment, especially the one where the cable was strung between two buildings on a catenary wire. I could change a 75159 line driver chip in about 90 seconds per station - less if the case screws weren't fitted (as was common - we got so used to changing these chips). In one extreme case - possibly a direct hit - we had to replace some melted connectors on the backbone cable.
The real pain with blown Econet line drivers was that the fault was usually manifest when a station was plugged in and switched off - it failed to disconnect from the bus and held the data pair such that no other traffic could pass. Suddenly there'd be a howl of users reporting "Line jammed" errors until the faulty station was disconnected from the network.
You can certainly get all sorts of weird effects from differences in ground potential between buildings. These days, galvanic isolation - and therefore immunity to ground potential differences and electrical storms - is easy to achieve using fibre. Unlike the 1980s, fibre is affordable and easy to deploy.
It's no accident that there's fibre linking our house to the outbuilding where we keep our servers in an air-conditioned room. We may have got away with stringing some external grade Category 5e UTP cable between the buildings, but it's not worth it. One fried switch would more than pay for the cost of the fibre. We did it the easy way, installing a pre-terminated fibre prepared off-site - deploy the fibre, pull the PVC tubing off the cable gland and click the individual LC terminated fibres into an LC patch panel.
The only thing we use external grade Category 5e cable for is telephone.