About 20 years ago when that huge transformer farm along the 303 Loop and El Mirage road went up in smoke, it eliminated about 1/3rd of the electric switching capacity here in the valley, right at the beginning of summer. The huge transformer that exploded was of the type that are so large, they can't be flown on even the world's largest plane, so they must be trucked. And it takes weeks of slow careful travel on custom trucks over carefully selected roads to get them from across the country to here.
For those of you here at the time who remember, the entire metro area was trying to ration their use of electricity to keep from over-stressing the remaining transformers keeping the grip barely up and running. There was legitimate fear that if one of the other gigantic transformers blew,...people would dies. Grocery stores would lose perishables. Ice would not be able to be made. Air conditioning would be gone. All in the middle of a Phoenix summer. It was a tense time that felt like it could become an apocalypse any day. The replacement transformer finally made its way here and was installed, and things returned to normal. But it showed how vulnerable we all are.