MELISSA BLOCK, host:
From NPR News, this is ALL THINGS CONSIDERED. I'm Melissa Block.
ROBERT SIEGEL, host:
And I'm Robert Siegel.
The power is coming back on in South Florida after a massive blackout this afternoon. State officials say as many as 3 million people across the state were affected. The utility for the area, Florida Power & Light, traces the outage to an equipment failure in an electrical substation. That sparked a cascading series of blackouts that affected people as far north as Orlando and Tampa.
The outage began shortly after 1 p.m. And the mayor of Miami-Dade County, Carlos Alvarez, says the main problem was the loss of traffic lights.
Mayor CARLOS ALVAREZ (Miami-Dade County): It's been a massive inconvenience because of traffic congestion. You can't describe this as an emergency because it has not. It's just the fact that we have a traffic problem to begin with.
SIEGEL: Well, joining us now from Miami to talk about what happened today is NPR's Greg Allen.
And Greg, do we have a sense of what caused all this?
GREG ALLEN: Well, Robert, Florida Power & Light officials traced the beginning of this whole series of events to an electrical substation in Miami-Dade County. They say some piece of equipment in that substation failed. When that happened, it cut power which goes south to the nuclear plant at Turkey Creek. These are a couple of nuclear power plants that generate a lot of power in Florida, especially South Florida, that when the power was reduced to Turkey Creek, those two nuclear plants shut down. It was an emergency shut down done for safety reasons. They say there was never a problem there. This happened just as it should happen.
But when those plants kicked off, that created this whole cascading series of effects that then shut down parts of the grid, from Miami all the way north up, as you say, to Orlando and Tampa.
SIEGEL: And what was the impact in Miami, to begin with?
ALLEN: Well, of course, this - one of the other factors today was the fact that it was very warm in Miami, in the '80s, and even warmer than we usually see this time of the year. And that had air-conditioners humming. So, of course, first thing that happened there is people lost air conditioning.
But the big impact, as Mayor Alvarez said there, was on traffic. It really put many parts of the city into a gridlock. Traffic lights were out. And when they lost power, many people at work then decided to take off and go home early. So, they had all these people on the roads, no traffic lights.
Police were out very quickly, directing traffic. But as I've mentioned, there was gridlock. You couldn't do much. Hospitals lost power, of course, here in Miami. And many of those switched over immediately to emergency power. They say it didn't really affect them too badly.
The airport - the international airport here in Miami and the port authority both say their operations were unaffected. They went to emergency power, and they were able to have their planes and ships go out on time.
One concern with the schools, but they all - the schools that lost power all kept their kids in class. The class - were held on emergency power, and the students were released on regular schedules.
So, really, the main impact, as far as we can tell, has been on that terrible Miami traffic.
SIEGEL: I want you to explain some discrepancy in numbers, about the number of people in Florida affected statewide by this. The power company says 700,000. State officials say as many 3 million.
ALLEN: Well, Florida Power & Light say it was 700,000 in its service area, which really just goes up to Palm Beach County to the southern part of the state. But as we've mentioned, this was a classic cascading failure, and so you had systems affected all the way up to Tampa, Orlando, Daytona Beach, much further north.
So, as many as 3 million people may have lost their power just for a few seconds or a few minutes before the circuits were reset and they got their power back. So it really did affect a good part of the state at its peak.
SIEGEL: Thank you, Greg.
ALLEN: My pleasure, Robert.
SIEGEL: It's NPR's Greg Allen in Miami.