52.3.2.4 Hazard Mitigation Analysis

A failure mode and effects analysis (FMEA) or other approved hazard mitigation analysis shall be provided to the AHJ when any of the following conditions are present:

1. Battery technologies not specifically identified in Table 52.3.1 are provided.
2. More than one stationary storage battery technology is provided in a room or indoor area where there is a potential for adverse interaction between technologies.
3. When allowed as a basis for increasing maximum allowable quantities as specified in Table 52.3.2.2.1.

The analysis shall evaluate the consequences of the following failure modes, and others deemed necessary by the AHJ. Only single failure modes shall be considered for each mode:

1. Thermal runaway condition in a single module or array
2. Failure of a battery management system
3. Failure of a required ventilation system
4. Voltage surges on the primary electric supply
5. Short circuits on the load side of the stationary battery storage system
6. Failure of the smoke detection, fire suppression, or gas detection system

The AHJ shall be permitted to approve the hazardous mitigation analysis provided the consequences of the FMEA demonstrate the following:

1. Fires or explosions will be contained within unoccupied stationary storage battery system rooms for the minimum duration of the fire resistance rated specified in 52.3.2.1.3.1 or 52.3.2.1.3.2, as applicable
2. Fires and explosions in stationary storage battery system cabinets in occupied work centers allow occupants to safely evacuate
3. Toxic and highly toxic gases released during charging, discharging, and normal operation shall not exceed the permissible exposure limit (PEL)
4. Toxic and highly toxic gases released during fires and other fault conditions shall not reach concentrations in access of IDLH level in the building or adjacent means of egress routes during the time deemed necessary to evacuate from that area
5. Flammable gases released from batteries during charging, discharging, and normal operation shall not exceed 25 percent of the lower flammable limit (LFL)

Construction, equipment, and systems that are required for the stationary storage battery system to comply with the hazardous mitigation analysis shall be installed, maintained, and tested in accordance with nationally recognized standards and specified design parameters.