INERTIA REPL :: Inertia Engineering Inertia Engineering and Machine Works, Inc. manufactures medium voltage switchgear, automation products and specialized equipment, components for the electrical industry. INERTIA_REPL, INERTIA Engineering and REPL, a manufacturer of heat-shrinkable power cable accessories Established in 1995, Inertia Engineering and Machine Works, Inc. manufactures medium voltage switchgear, automation products and specialized equipment and components for the electrical industry. INERTIA_REPL is a joint venture between INERTIA Engineering and REPL, a manufacturer of heat-shrinkable power cable accessories for over twenty-five years.