Fire Safety

What We Know

UL 9540A Testing

Each Tesla Megapack 3 unit undergoes UL 9540A testing, the most rigorous fire safety standard for battery energy storage systems. This testing evaluates thermal runaway behavior at the cell, module, and unit level to validate that the design prevents fire from spreading beyond a single unit.

Built-In Fire Suppression

Every Megapack unit includes an integrated fire detection and suppression system. The system monitors temperatures continuously and can automatically activate suppression without human intervention. Key features include:

• 24/7 thermal monitoring: sensors detect temperature anomalies in real time
• Automatic shutdown: the system isolates affected cells before conditions escalate
• Liquid cooling: active thermal management keeps batteries within safe operating ranges
• Non-propagation design: the design prevents fires in one module from spreading to adjacent modules

NFPA 855 Compliance

We designed the project to meet NFPA 855 (Standard for the Installation of Stationary Energy Storage Systems). This standard covers siting, spacing, fire suppression, ventilation, and emergency response, setting clear requirements for:

• Minimum separation distances between units and property lines
• Fire department access roads and hydrant placement
• Hazardous material containment
• Ventilation to prevent gas accumulation

Emergency Response Planning

We are working directly with Charlton Fire Chief Rob Barton on a site-specific emergency response plan. This includes:

• Pre-incident planning with the fire department
• On-site familiarization visits for first responders
• Specialized training on battery storage fire response
• Clear protocols for notification and evacuation if ever needed

What We're Still Studying

• Final fire suppression system specifications: our engineers are developing detailed system specifications, which we will include in the consolidated permit application
• Mutual aid coordination: we are holding discussions with surrounding fire departments to coordinate mutual aid
• Detailed thermal runaway modeling: we will complete a site-specific analysis as part of the EFSB filing

What You Can Influence

• Emergency response priorities: tell us what matters most to you about fire safety at our upcoming Fire Safety Open House
• Information requests: if you have a specific safety question, submit it through Share Your Voice and we will answer it publicly
• Open house feedback: attend the Fire Safety Open House with Chief Barton to see safety features firsthand and ask questions directly