The only limitation to number of hours worked that I'm aware of is for young people. Unless there's been a change, child labor laws say that children during the school year can be scheduled no more than 3 hours/day, no more than 18 hours/week, no work hours after 9 p.m. Outside the school year, it increases to no more than 8 hours/day, 40 hours/week or after 9 p.m. This rule applies to those at least 14 through 16.
