According to NFPA 855, individual energy storage system units should generally be separated by at least three feet, unless the manufacturer has conducted large-scale fire testing (part of UL 9540A) to prove a smaller distance is safe. This prevents a fault in one unit from spreading. Batteries of the unsealed type shall be located in enclosures with outside vents or in well ventilated rooms and shall be arranged so as to prevent the escape of fumes, gases, or electrolyte spray into other areas. Ventilation shall be provided to ensure diffusion of the gases from the battery and. Installing a battery energy storage system is a significant step toward energy independence. To ensure your system operates safely and efficiently, proper installation is paramount. For battery racks, there shall be a minimum clearance of 25 mm (1 in. Remove the breaker protection plates.