If an employee works from 3:00 PM Wednesday to 11:30 PM Wednesday then that should only constitute 8 hours worked but how many hours are peak or off peak, i.e. where is the ½ hour break deemed to be?

How are you recording start and end times, it would be easier with time and date in one cell for start time of a shift and the same for the end of shift, or do you need to do it another way?