The GP's statement is about relying on third parties, multiple power lines with generators you don't own on the other side falls under it.
Fun related fact: My first employee's main office was in former electonics factory in Moscow's downtown powered by 2 thermal power stations (and no other alternatives), which have exact same maintenance schedule.
Fun related fact: My first employee's main office was in former electonics factory in Moscow's downtown powered by 2 thermal power stations (and no other alternatives), which have exact same maintenance schedule.