A modular slot motor assembly and arc plate assembly combination for a circuit breaker is disclosed. The modular slot motor assembly is positioned proximate the arc plate assembly by lockingly securing it to a subcomponent housing in order to better provide an enhanced separation of the contact arms. During a short circuit event the modular slot motor assembly provides added acceleration to a moving contact arm. To protect the modular slot motor assembly from damage, an insulating casing is applied to at least a portion of the modular slot motor assembly.