It will happen at rock bottom. Something terrible somewhere or multiple places will be going on, and BOOM all the power will go out. Communications will be cut, who knows what else will happen.
This is something I have been worrying about for years now!
And the energy companies are so unconcerned about security it is just aggravating beyond belief!
Look at what happened quite recently at that substation for, what was the company,... PG&E, AT&T ? that those “unknown persons” (of middle-eastern appearance and firing off AK-47 -appearing firearms) attempted to greatly damage and force to shut down the establishment they were attacking!
How much more of a wake-up call do we need?