The second LHC long shutdown period (LS2) was a crucial opportunity to complete the consolidation and upgrade projects for the CMS Resistive Plate Chambers (RPCs). The consolidation included detector maintenance for gas tightness, HV (high voltage), LV (low voltage) and slow control operation. Dedicated studies were performed to understand the behaviour of RPC currents with comparison to RUN 2. This paper summarises the activities performed and commissioning
of CMS RPC on the surface (For RE4) and for full detector in CMS cavern in different operating conditions.