Abstract: A cassette for a draw-out circuit breaker apparatus is disclosed. The cassette comprises a base having a front edge and a back edge, the back edge defining a back plane, a set of shutters disposed at the back plane and configured to open and close, and a set of shutter locks extending from the front edge to the back edge and in operable communication with the set of shutters. The shutter locks are biased toward a first position. In response to the shutter locks being driven toward a second position, the shutters are restrained from opening. The shutter locks are configured to be restrained in the second position.