Prove Battery-Rack Safe State Before Relocation or Disassembly

What to check before the work begins

Before this battery rack is moved, opened, or disconnected, show every source and conductor that can remain energized—including BPU, auxiliary, and control supplies—and the approved method for isolating, testing, insulating, and controlling the battery energy that remains.

Issue a controlled rack-by-rack source and energy map covering the UPS connection, BPU or rack-control supply, charger, monitoring, heaters, auxiliary sources, inter-rack links, grounding, and the battery modules' retained electrochemical energy
Identify and isolate every isolatable source at the exact rack or work boundary, using the project-approved sequence and field device identity
Prove the required de-energized state at defined test points with an approved instrument and method, while explicitly recognizing that battery modules and some conductors may retain voltage and fault energy
Disconnect, separate, cover, cap, or insulate exposed conductors and terminals in accordance with the approved design, OEM instructions, and safe-work method before mechanical handling begins
Define the project-specific stored-energy condition, rack sequence, mechanical handling controls, short-circuit prevention, tools, barriers, monitoring, hold points, and emergency response for energy that cannot be removed by isolation
Obtain an independent field verification before releasing each rack or defined work section and repeat the check after any change, interruption, handover, or unexpected indication

What the sources describe

On September 26, 2025, a fire at South Korea's National Information Resources Service disrupted government services during relocation of UPS-connected lithium-ion battery racks. Final police findings, based on the National Forensic Service appraisal, stated that all BPU control boxes on racks 1 through 8 should have been isolated after the UPS was shut down, but only rack 1 was isolated; BPU conductors also were not disconnected and insulated before work proceeded. The exact arc or short-circuit point was not disclosed. The Ministry later reported that all 709 affected administrative information systems were restored after 95 days.

Evidence to confirm

Controlled battery source and retained-energy map
electrical contractor · Before the relevant work begins
Every rack and work section identifies the UPS connection, rack/BPU control or auxiliary supplies, interconnections, grounding, isolatable sources, and electrochemical energy that remains.
Rack-by-rack isolation and device-identity record
electrical contractor · Before the relevant work begins
Each required isolation point is matched to the controlled drawing and exact field device, operated in the approved sequence, and independently verified before release.
Approved electrical state-verification record
electrical contractor · Before the relevant work begins
Named test points, instrument identity and suitability, pre-use and post-use checks, readings, and acceptance criteria prove the required state for isolatable circuits without claiming the battery modules are de-energized.
Exposed-conductor disconnection and insulation record
electrical contractor · Before the relevant work begins
Every conductor or terminal exposed by the work is disconnected, separated, capped, covered, or insulated as required by the approved method before handling begins.
Project-approved stored-energy and handling basis
electrical contractor · Before the relevant work begins
The responsible technical authorities have defined the accepted battery condition, sequence, short-circuit prevention, tools, barriers, mechanical handling, monitoring, stop criteria, and emergency response for retained energy.
Independent section release and final as-left record
electrical contractor · Before the relevant work begins
A named verifier releases each rack or section before disturbance, changes and anomalies are dispositioned, and all final connections, covers, controls, labels, and protection are reconciled before re-energization or turnover.

Conditions to resolve before proceeding

The source and energy map does not match the field installation or a conductor, rack, control box, or supply cannot be positively identified
Any source designated as isolatable has not been isolated and verified at the approved boundary
The test method, test point, or instrument is not approved, or any reading is unexplained
A conductor or terminal that can be exposed during the work lacks the required disconnection, separation, covering, or insulation
The battery state or retained-energy condition is outside the project-approved handling basis
The work sequence, rack identity, temporary connection, personnel, tooling, or environmental condition changes without re-evaluation
Any arc, heat, smoke, odor, swelling, abnormal voltage, alarm, damage, or unexpected electrical response occurs

When this applies

Installation turnover
Startup

Assess each lesson against your project, equipment, and local requirements with the people responsible for the work.

Limitations and context

Applies when: A battery rack, cabinet, string, module assembly, cable, or associated BPU/control enclosure will be moved, opened, disconnected, reconfigured, or dismantled
Applies when: The battery system retains electrochemical energy while one or more rack-level auxiliary, monitoring, control, heater, charger, or other circuits may be separately energized
Applies when: The work can expose conductors or create a new short-circuit, arc, mechanical, or thermal path
Outside scope: Visual inspection that exposes no conductor and changes no battery or circuit state
Outside scope: Routine battery-autonomy testing, permanent battery-string topology acceptance, or source-transfer bridge-time verification governed by another Pearl
Outside scope: Emergency firefighting, battery disposal criteria, or generic electrical safety work unrelated to battery-rack handling
Outside scope: Work the responsible electrical authority determines has no credible retained electrical or electrochemical energy exposure
Criminal and contracting findings are not used to assign blame in the Pearl control.
Criminal, supervisory, and subcontracting findings are not used to assign blame or prescribe project staffing.
It does not describe the battery-work mechanism or distinguish physical repair time from service-restoration dependencies.
It does not publish the underlying electrical drawings, test records, or forensic laboratory report.
The Ministry notice verifies the incident and service disruption but does not describe the ignition mechanism or battery-rack work state.
The attached Korean-language press-release files were not retained in the Pearl Package.
The complete Daejeon police case file and National Forensic Service report are not publicly available in the source set.
The complete police case file and National Forensic Service report are not public in the source.
The exact arc or short-circuit location, complete battery one-line, BPU supply architecture, detailed work sequence, and state of charge at ignition are not established here.
The forensic finding ruled out thermal runaway as the initiating mechanism but does not make battery fire escalation irrelevant after ignition.
The recovery update establishes duration and system count but does not attribute each system interruption solely to direct fire damage.

Prove Battery-Rack Safe State Before Relocation or Disassembly

What to check before the work begins

What the sources describe

Evidence to confirm

Conditions to resolve before proceeding

Sources

Minister convenes situation assessment meeting and activates crisis response headquarters after NIRS fire

All 709 NIRS systems restored after the fire

Police announce final findings in National Information Resources Service fire investigation

National Forensic Service findings: work proceeded without all battery-rack power isolated