NIST 800-53 REV 5 • PHYSICAL AND ENVIRONMENTAL PROTECTION
PE-11 — Emergency Power
Provide an uninterruptible power supply to facilitate {{ insert: param, pe-11_odp }} in the event of a primary power source loss.
Supplemental Guidance
An uninterruptible power supply (UPS) is an electrical system or mechanism that provides emergency power when there is a failure of the main power source. A UPS is typically used to protect computers, data centers, telecommunication equipment, or other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious mission or business disruption, or loss of data or information. A UPS differs from an emergency power system or backup generator in that the UPS provides near-instantaneous protection from unanticipated power interruptions from the main power source by providing energy stored in batteries, supercapacitors, or flywheels. The battery duration of a UPS is relatively short but provides sufficient time to start a standby power source, such as a backup generator, or properly shut down the system.
Practitioner Notes
An uninterruptible power supply (UPS) provides temporary power during outages, giving your systems time to shut down gracefully or switch to a backup generator. Without a UPS, a power flicker can corrupt data and crash systems.
Example 1: Install rack-mounted UPS units (APC Smart-UPS, Eaton 5PX, or CyberPower) for all server racks and network equipment. Size each UPS to provide at least 15-30 minutes of runtime at current load. Configure UPS management software to trigger graceful OS shutdown if power is not restored within 10 minutes.
Example 2: For critical workstations (security consoles, reception systems), provide desktop UPS units. Set up automated email or Teams notifications when the UPS switches to battery power so IT staff are alerted immediately. Test UPS batteries annually and replace them on the manufacturer's recommended schedule.