Sec. 11. If a child:
(1) is adjudicated a delinquent child for a delinquent act; and
(2) becomes a ward of the department of correction under this chapter (or IC 31-6-4-15.9 before its repeal);
the department of correction may not at any time during the child's confinement impose a departmental classification system on the child that would cause the child to be confined in a correctional facility for longer than the period of confinement under a departmental classification system that existed on the date that the child committed the delinquent act.