Faults blow fuses or in extreme cases cause sections of the power grid to just shut down.
Never heard of "blackouts" ??
Electrical power systems are built to stand overhead cables being struck by lightning, which causes a large overload every time it happens. The majority of the time things just carry on working, occasionally something trips or fuses go.
A wire (cable) has to be massively overloaded to "blow up", the electrical system in general is built with overload protection, circuit breakers and fuses at every level so cables can never be overloaded if everything is used correctly.
That's part of laws and regulations - at any point a larger cable "splits out" to smaller cables, each individual cable has to have circuit breakers or fuses so the smaller cable cannot be overloaded.
It's nothing to do with cables blowing up, it is to prevent even a moderate overload that could overheat any wire or cable to the point it could cause a fire.
eg. you have a fuse board or "consumer unit" in your house to protect all the cables from that, and rather larger things like these in the distribution system from power stations:
That (fire) is the only real, destructive, hazard. If everything is used properly it should never happen.
It takes something like someone stupidly overloading a cable, such as by running several electric heaters from the same outlet rather than one per outlet.
And !!! they have bypassed the fuse that protected the cable to the outlet, because it kept blowing...
That's just asking for a house fire.
Data cable work at low voltages and do not carry any power, as such. Most undersea cables are now fibre optic rather than copper, as fibre systems can handle far more data.
(Submarine means under water).