NFPA 855 2026 Edition: Key Changes for TRPP Systems

The NFPA 855 2026 edition introduces significant updates for stationary energy storage systems (ESS), focusing on thermal runaway propagation protection (TRPP) systems. This third revision, expected in fall 2025, adds new definitions and requirements for active TRPP systems that detect gas leaks or abnormal temperature rises and release heat-absorbing agents to prevent thermal runaway spread. Key changes include mechanical piping compliance with ASME B31.1 or B31.3, electrical and control requirements using a listed fire alarm control unit with backup power per Section 4.10, and commissioning, inspection, testing, and maintenance procedures aligned with applicable NFPA standards. The TRPP system must undergo large-scale fire testing to verify effectiveness. These updates aim to enhance safety in residential, commercial, and grid-scale ESS deployments, addressing dynamic industry developments.