There are two EPSS levels defined in the standard: Level 1 and Level 2. Level 1 EPSS systems provide power where failure would result in “loss of human life or. NFPA 110 is the standard for emergency and standby power supply systems (EPSS): the rules for how generators, transfer switches, and fuel systems must be installed, tested, and maintained. It classifies systems as Level 1 (failure could cause loss of life) or Level 2 (less critical), and sets the. An emergency power supply system is a system that includes the emergency power supply as well as a system of conductors, disconnecting means, overcurrent protective devices, transfer switches, and all control, supervisory, and support devices up to and including the load terminals of the transfer. Emergency and standby power systems are designed to provide an alternate source of power if the normal source of power, typically the electric utility service, should fail. Reliability of these types of systems is critical and good design practices are essential. Classification of Emergency and. This document provides the framework for the design, installation, maintenance, and testing of backup power systems, ensuring they perform when the grid fails.