Why might computer equipment remain energized after firemen trip the main breakers?

The reason computer equipment may remain energized after firemen trip the main breakers is that the uninterruptible power supply (UPS) has switched to battery operation. A UPS is designed to provide backup power to critical equipment in the event of a power outage or interruption. When the main breakers are tripped, indicating a loss of electrical supply from the grid, the UPS can detect this loss and automatically switch to its internal batteries to continue supplying power to connected devices. This ensures that essential systems, like computer servers or data storage units, can remain operational for a period of time, allowing for safe shutdowns or continuity of critical functions.

Alternative grid sourcing, emergency power activation, or circuit faults typically do not explain the immediate retention of power to equipment upon the tripping of main breakers. The UPS operation reflects a specific design purpose for power continuity and resilience in critical infrastructure environments.