Lead-acid UPS battery fire at data centre in Chiba, Japan
2024Published 12 Oct 2026Responsible editor: Chief Editor
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What happened
In February 2024 a fire broke out in the UPS room of a data centre in the area served by the Inzai District Fire Department in Chiba Prefecture, Japan. The UPS room supplies power to the server rooms from stored battery power until backup generators can be started during a power cut. One cubicle-type lead-acid battery unit was burned. From the outbreak of the fire to its extinguishment took seven hours.
According to the fire department, crews lacked knowledge of the building structure and fire equipment, liaison with building staff and security guards did not work, and effective firefighting of the electrical fire could not be carried out. The fire department then led a cause investigation with the electrical design and construction contractor, the battery manufacturer and the building owner, including site inspections, forensic examinations and combustion experiments.
Contributing factors
The cause investigation found a defect in the manufacturing process of the lead-acid batteries. The manufacturer voluntarily recalled batteries made during the affected period. By 31 March 2025, 4,176 of 4,220 batteries (about 99%) had been recovered. The fire department identified the fire spread mechanism, but the source does not give details of it.
Lessons learned
- Fire crews attending data centres need prior knowledge of the building structure, fire systems and battery room layout.
- Emergency contact points and docking points with building staff and security should be agreed and tested before an incident.
- Electrical battery fires need firefighting methods that have been verified by testing with the relevant agents before an incident.
- Battery racks should be designed to limit ground-fault paths from electrolyte leaks and short-circuit paths in cables, with fire-resistant cable treatment.
- Battery manufacturers should trace production defects across batches and run recalls where a defect may exist.
More lessons on fire suppression and firefighting, theft, arson and site security, electrical protection and isolation, design, standards and commissioning, from every incident on the register.
Source
Published 2026-10-12. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.
