(C) Spaces About Battery Systems
For battery racks, there shall be a minimum clearance of 25 mm (1 in.) between a cell container and any wall or structure on the side not requiring access for maintenance. Battery stands shall be permitted to contact adjacent walls or structures, provided that the battery shelf has a free air space for not less than 90 percent of its length.
Informational Note: Additional space is often needed to accommodate battery hoisting equipment, tray removal, or spill containment.