My work has it, max of 240 hours carry over, but can go over that during the year.
Our fiscal year is July 1 to June 30, so I am only half way through my year, I think I have 250 hours right now, and get ~7 more every 2 weeks.
I rarely take off, and like to keep as much time as possible "just in case" since our time is both vacation and sick time.