I just realized something more or less funny.
With my new character I just fixed Helios One once again and while I was checking out the surroundings for stuff I might have overlooked in my past playthroughs, I saw the power generators and the power poles... which alle have been broken. This was the moment where I realized that there is not a single 100% working powerline in the whole area, because most of the power poles are somehow damaged. Helios One is now generating power for nothing, same with Hoover Dam.
I know, I know, this is super nitpickery. :> Just wanted to say it.