Very topical oh Unhinged one! 38 hours per week is to bring the award in line with the new Federal Government Laws (Jan 2010). You can only work, on average over a 12 month period, a 38 hour week. So a 45 hour 'duty' week now effectively needs to include 7 hours of lunch hours/breaks so that the employee only 'works' 38 hours per week.
