An emergency power system (also called an Emergency Power Supply System or EPSS) is an independent power source that automatically activates when the normal utility power supply fails. These systems are engineered to provide immediate backup electricity to critical systems and equipment, ensuring continuous operations during outages.
The National Electrical Code (NEC) defines three distinct categories: Emergency Power Systems (Article 700) for life safety with 10-second restoration, Legally Required Standby Systems (Article 701) for rescue operations with 60-second restoration, and Optional Standby Systems (Article 702) for business continuity.
