Unwanted electrical arcing poses significant risks to the reliability and safety of electrical and electronic systems. To enhance predictive capabilities and deepen understanding of arc behavior, this comprehensive numerical model simulates transient arc discharge phenomena in a circuit breaker environment. The model employs a full 3D magnetohydrodynamics-based Arc Discharge multiphysics interface, capturing the complex interplay between thermal, electromagnetic, and fluid dynamic effects during arc formation and evolution. A dynamic moving mesh with remeshing is implemented to accurately resolve topological changes associated with mechanical switching actions. Furthermore, the model is coupled to an external electrical circuit, enabling realistic simulation of arc-circuit interactions under operational switching conditions. This integrated approach provides a robust framework for investigating arc dynamics and supports the development of more effective arc mitigation and control strategies in power systems.