New employees shall not be entitled to work overtime until the completion of their four hundred eighty (480) actual hours worked of their probationary period, unless all permanent employees in the affected classification within the unit who desire to work overtime are working and/or the overtime is associated with their normal work assignment and is contiguous to their normal work day. When a new employee has completed the original four hundred eighty (480) actual hours worked of their probationary period the employee shall be charged with the hours of the employee having the greatest amount of hours in their classification plus the hours earned while a probationary employee.