The 1000+ bus short circuit, protective device coordination study, and arc flash hazard analysis was completed for the new 4000 amp, 480V, 3 phase essential N+3 system with (4) 1500KW generators in scope. The study also included the 4000 amp,480V, 3 phase critical N+3 system with the (4) 1500kw generators in scope. Downstream distribution included distribution panels, panelboards, transformers, MCC's, and UPS systems to back up the facility should a loss of normal power take place.