My manager claims it is the law that all employees, including salaried, exempt are required to take at least 1/2 hour break every six hours. I don't believe this to be true. Where can I find the answer?

Maine does require a 1/2 hour lunch break.

http://www.dol.gov/esa/programs/whd/state/meal.htm

http://janus.state.me.us/legis/statutes/26/title26sec601.html