[Micele]

.... After 3h44:

The last visible flame went out and the test was over.

Following the test, they unsurprisingly found out that “all of the energy pods were damaged and there was no stranded energy within the Powerpack.”

NFPA concluded that a prolonged fire outside the Powerpack could definitely induce the Powerpack into thermal runaway, but they found that the consequences were confined to the pack and didn’t propagate:

“However, no violent projectiles, explosions, or bursts (other than a overpressure release of the thermal door refrigerant) were observed during the test while the Powerpack was exposed to the burners, while it was in a free burn state, or after flames were no longer visible. Flames remained mostly confined to the Powerpack itself. Weaker flames emanated from the exhaust vent of the Powerpack, the front thermal door grill, and around the front thermal door seal at varying times throughout the test.”

Most importantly, they determined that the exterior temperatures at the Powerpack cabinet “would not pose a fire spread hazard” if Tesla’s installation standards are respected.

In conclusion, if a fire starts from inside a pod, it doesn’t propagate to the rest of the Powerpack. And if a fire starts outside the Powerpack, it won’t spread to other Powerpacks around it. Of course, there are also several safety features preventing those things from ever happening, but the NFPA’s tests were for worst case scenarios.