During the Hurricane Sandy/FRANKENSTORM update this evening, Mayor Bloomberg and Con Edison CEO Kevin Burke said that Con Ed are considering preemptively shutting down underground power networks in many parts of Lower Manhattan and Brooklyn tonight. "We're looking at, and I think it's likely that, we'll be preemptively shutting down two underground networks in Manhattan—the Fulton network and the Bowling Green network, which essentially covers the areas between Broadway, the East River and south of the Brooklyn Bridge—and also perhaps Brighton Beach by Coney Island," Burke said. And just now, Con Ed just shut down power to the Bowling Green Electrical Network, apparently Wall Street to the tip and then east of Broadway. Update below—Brooklyn now affected.

"We're doing that to reduce the likelihood of damage to both our equipment, and our customers equipment. If the equipment is energized, as you can imagine, when salt water gets on it you'll have shorts," he added. Already, around 47K customers are without service right now, and Con Ed expects there is a significant chance of major flooding around the city that can bring down even more.

"In addition to that, we're looking throughout the city at other places where we provide fairly high voltages to customers, above the typical voltage we supply to residential customers or small commercial customers," he said. "And we have identified 20 large installations...and we're going to watch those, and if we think water is going to get into our facilities and the customers facilities, we're going to preemptively shut those services off." Burke didn't indicate what exactly those other 20 large installations are, but he said it could impact around 7900 customers, who have already begun to receive automated calls about the possible shutdown.

Burke said Con Ed was continuing to watch what happens with the steam system, and in a worst case scenario, they may have to reduce or cut off steam service to everyone south of 14th Street in Manhattan. He also implored people: "if you see a wire down, assume that wire is energized." You can call 1-800-75-CON-EDISON or 311 if you see one.

Update: Now power is shut down in Brighton Beach, Brooklyn. We're getting reports of brownouts in Greenwich Village and lights have definitely been flickering in Upper Manhattan!

Also: Time Warner seems to be out in Brooklyn Heights, Cobble Hill and Williamsburg.

Update: Power was shut off to all of Manhattan south of 39th Street.