NEW YORK, Aug 15 - The New York Stock Exchange said on Friday it will open on time for regular trading using back-up power after a blackout swept across swaths of the eastern United States and Canada late Thursday afternoon. The NYSE will open on time, spokesman Ray Pellecchia said. He said it would be using a back-up power source. Large sections of the eastern United States and Canada lost power after the close of regular trading on Thursday, leaving parts of New York, Detroit, Cleveland and Toronto without electricity.//