Insurers Now Say On-Site Batteries Raise Fire Risk 10x: How to Keep Your Facility Insurable

The “10x” figure in this headline should not be treated as a universal insurance rating. Underwriters do not apply one multiplier to every battery installation. They evaluate chemistry, stored energy, location, separation, fire protection, monitoring, operating procedures, and the quality of the supporting documentation.

The message behind the number is still important: on-site lithium-ion batteries are increasingly treated as a high-severity property and business-interruption exposure. A battery event can produce thermal runaway, intense heat, flammable gases, smoke, reignition, and extended equipment isolation. For a data center, the consequence is not limited to replacing a battery cabinet. It may include damage to switchgear, cooling systems, network infrastructure, and the business systems those assets support.

Why insurers are scrutinizing on-site batteries now

Data centers are deploying more batteries to support UPS systems, microgrids, peak-load management, renewable integration, and grid-interactive operations. At the same time, AI workloads are driving higher power density and reducing the margin for electrical or thermal incidents.

A conventional UPS battery installation already requires disciplined maintenance. Larger battery energy storage systems introduce additional concerns:

• Thermal runaway: A failed cell can release heat and gases that cause adjacent cells or modules to fail.
• Fire propagation: A cabinet fire may spread to neighboring cabinets if spacing, barriers, or system-level testing are inadequate.
• Deflagration risk: Accumulated gases can ignite if ventilation and explosion-control measures are poorly designed.
• Reignition: Damaged lithium-ion cells can remain hazardous after the initial fire appears to be controlled.
• Operational disruption: A battery incident can force shutdowns, restricted access, extended fire watch, and replacement of associated electrical equipment.

The result is a more demanding underwriting process. Insurers increasingly want evidence that the installation is not merely code-compliant on paper, but designed, tested, monitored, and maintained as a complete system.

Why the status quo is failing

Many facilities still manage batteries as if they were passive components inside a UPS. That approach misses the changing risk profile of high-capacity lithium-ion installations.

Thermal Management is now a central underwriting issue. Battery rooms must be evaluated for temperature control, ventilation, off-gas detection, fire detection, and the interaction between battery equipment and adjacent cooling systems. A data hall designed for high availability cannot assume that its clean-agent suppression system will address every battery hazard.

The same applies to Redundancy. N+1 or 2N UPS architecture protects against equipment failure, but redundancy alone does not prevent a battery fire from affecting both systems if cabinets are installed too close together or share an inadequately protected room.

There is also a documentation gap. A facility may have a UL 9540-listed system but lack installation-level evidence for the actual cabinet arrangement, room dimensions, ventilation strategy, and suppression design. Underwriters and authorities having jurisdiction increasingly expect those details to align.

What underwriters typically look for

1. Product certification and test evidence

Start with the difference between two important standards:

• UL 9540 addresses the safety of energy storage systems and equipment.
• UL 9540A evaluates thermal runaway fire propagation and related hazards through cell-, module-, unit-, and installation-level testing.

UL Solutions describes installation-level testing as an evaluation of fire-protection effectiveness, heat and gas release, deflagration risk, and potential reignition. Its UL 9540A test-method overview is a useful reference for project teams and insurance liaisons.

Underwriters may request:

• UL 9540 certification or listing documentation
• UL 9540A reports for the exact battery chemistry and system design
• Installation-level or large-scale fire-test evidence
• Manufacturer installation instructions
• Battery Management System specifications
• Confirmation that the installed configuration remains within the tested envelope

Do not assume that a report for one cabinet, rack arrangement, or enclosure automatically applies to a different layout. Changes in spacing, capacity, ventilation, suppression, or enclosure design may require additional engineering review.

2. Separation distances and fire-rated construction

Spacing is one of the first items reviewed during a risk survey. A commonly referenced baseline for indoor ESS layouts is 3 feet between battery arrays and from arrays to walls, subject to the applicable code edition, system capacity, test data, and AHJ approval.

For larger or more complex systems, the design may require:

• Dedicated battery rooms
• Noncombustible construction
• Fire-rated walls, floors, ceilings, and doors
• Separation from data halls, electrical rooms, and critical cooling equipment
• Clear access for emergency responders
• Physical barriers between racks or cabinets
• Outdoor placement away from critical buildings and exposures

NFPA 855 covers fire detection, suppression, explosion control, exhaust ventilation, gas detection, thermal runaway, and other ESS installation considerations. The 2026 edition of NFPA 855 also adds requirements related to emergency response planning and expands guidance for lithium-ion ESS risk mitigation.

The correct spacing is not simply the maximum amount that fits in an available room. It should be supported by the applicable code, UL 9540A or large-scale test data, the fire-protection engineer’s design, and the insurer’s risk-engineering requirements.

3. Detection, suppression, and explosion control

Underwriters want layered protection rather than one device expected to solve every failure mode.

A credible design may include:

• Smoke and heat detection
• Rack-level temperature monitoring
• Off-gas or combustible-gas detection
• Automatic alarm transmission to the building fire alarm system
• Engineered ventilation
• Automatic sprinkler protection
• Explosion prevention or deflagration-control measures
• Emergency shutdown and battery isolation
• Remote monitoring for alarms, temperature, state of charge, and system status

The design must account for the difference between a battery-room hazard and an IT-room hazard. Clean agents can protect sensitive electronics, but they should not be assumed to replace the fire-protection strategy required for a lithium-ion ESS installation.

Some projects reference sprinkler criteria such as 0.30 gpm/ft² over a 2,500-square-foot design area, but the final requirement depends on the adopted code, occupancy classification, system arrangement, manufacturer test data, and AHJ direction. Facilities should avoid copying a generic density or ventilation value into a design without a qualified fire-protection review.

4. Monitoring and real-time response

Remote monitoring is increasingly important to both resilience and insurability. A modern battery installation should provide actionable data, not just a green status light.

Monitoring should identify:

• Cell or module temperature anomalies
• Voltage imbalance
• State-of-charge and state-of-health trends
• Abnormal current or charging behavior
• BMS alarms
• Smoke, heat, or gas detection
• Ventilation status
• Suppression-system impairments
• Cabinet door or enclosure faults

Those alarms should be routed to the appropriate operations center, facility management platform, or network operations team. Remote visibility cannot replace physical inspection, but it helps staff identify developing conditions before they become a thermal event.

Ace Real Time Solutions supports power protection and installation services, including UPS, batteries, surge protection, voltage regulation, monitoring, and ongoing support. For mission-critical facilities, the objective is real-time awareness across the power chain: not merely backup power after the grid fails.

The Battery Insurability Roadma

Facility managers can improve their underwriting position with five practical steps.

1. Build a complete battery asset register

Document every UPS battery string, cabinet, rack, chemistry, capacity, installation date, location, and connected load. Separate conventional VRLA systems from lithium-ion ESS and identify systems that support high-density AI or continuous-production workloads.

Include one-line diagrams, room layouts, fire-rated assemblies, ventilation drawings, and emergency disconnect locations.

2. Obtain the complete testing package

Request UL 9540 certification and applicable UL 9540A documentation from the manufacturer or integrator. Confirm that the test data reflects the installed chemistry, enclosure, capacity, spacing, and operating configuration.

If your system relies on reduced spacing or a specialized suppression approach, obtain written engineering justification and AHJ approval before presenting the design to the insurer.

3. Commission an independent hazard review

Have a qualified electrical or fire-protection engineer review the installation against the locally adopted edition of NFPA 855, the International Fire Code, NFPA 72, NFPA 13, and applicable explosion-control requirements.

For a complex deployment, prepare a formal Hazard Mitigation Analysis covering thermal runaway, gas generation, fire spread, ventilation, responder access, emergency isolation, and recovery.

4. Formalize monitoring and maintenance

Create inspection and maintenance schedules for batteries, BMS equipment, detection, ventilation, sprinklers, fire alarms, and emergency power controls. Record test results, corrective actions, firmware changes, battery replacements, and impairments.

Use change management whenever capacity, cabinet position, battery chemistry, room use, or suppression equipment changes. The as-built facility must remain consistent with the approved design and test assumptions.

5. Submit an insurer-ready evidence package

Before renewal or construction approval, provide:

• Site and floor plans
• Battery asset register
• UL 9540 and UL 9540A records
• HMA and fire-protection design basis
• Separation-distance calculations
• Detection and suppression sequence of operation
• Monitoring screenshots and alarm history
• Maintenance records
• Emergency Response Plan
• Staff training and fire-drill documentation

This package gives the underwriter a measurable basis for evaluating risk instead of forcing the installation into a generic “battery hazard” category.

Keep the battery from becoming the facility’s weakest link

On-site batteries are essential to uptime, but they must be treated as engineered infrastructure: not as an afterthought attached to a UPS. Insurability depends on the complete lifecycle: product selection, tested behavior, spacing, fire protection, monitoring, maintenance, emergency response, and documented change control.

The strongest facilities engage the insurer, AHJ, electrical engineer, fire-protection engineer, and power-protection integrator before equipment is ordered. That coordination can prevent redesigns, reduce uncertainty during underwriting, and protect the availability targets expected of Tier III and Tier IV environments.

Visit Ace Real Time Solutions to request a power audit, download technical information, or discuss a battery and UPS solution designed around your facility’s uptime, safety, and risk objectives. You can also review enterprise power protection options for a project-specific solution design.

Frequently Asked Questions

What is UL 9540A testing?

UL 9540A is a standardized test method used to evaluate thermal runaway fire propagation in battery energy storage systems. Testing can examine cell-, module-, unit-, and installation-level behavior, including heat release, gas generation, fire spread, deflagration risk, and suppression performance.

How does UL 9540A affect insurance for data center batteries?

UL 9540A gives underwriters and authorities having jurisdiction technical evidence about how a specific battery system behaves during severe failure conditions. It can support decisions about cabinet spacing, fire-rated construction, suppression, ventilation, and explosion control. The test report must match the actual system configuration.

How can a facility keep an on-site battery installation insurable?

Maintain documented compliance with applicable codes and standards, use appropriately certified equipment, provide engineered detection and suppression, maintain required separation distances, monitor battery health in real time, and keep complete maintenance and emergency-response records. Engage the insurer and qualified design professionals before making material changes.