BESS Commissioning SWMS
Battery energy storage system commissioning — HV DC energisation, arc-flash, thermal runaway controls, state-based BESS permit requirements, and grid connection sign-off.
SWMS variants reference your state’s WHS legislation. Instant download after payment.
Battery Energy Storage System (BESS) commissioning involves the final energisation, configuration, and grid synchronisation of lithium-ion battery installations ranging from behind-the-meter commercial units to utility-scale containerised arrays. The work exposes commissioning engineers and electricians to lethal DC string voltages frequently exceeding 1,000 V, arc-flash incident energies capable of producing third-degree burns, and the latent risk of thermal runaway with toxic vented gas including hydrogen fluoride and carbon monoxide. Under WHS Regulation 2025, BESS commissioning is classified as high-risk construction work because it combines energised electrical installation with substantial fire and explosion potential, triggering mandatory SWMS preparation before work commences. AS/NZS 5139:2019 and the NSW Code of Practice for BESS Installations 2024 further require documented commissioning procedures, isolation verification, and a permit-to-work system. A site-specific SWMS is the regulatory mechanism that consolidates these obligations into a worker-consulted, signed-on document retained for the life of the installation plus statutory periods.
Hazards identified
7 hazards covered, sorted by priority.
Third-degree burns, blast lung injury, retinal damage from UV flash, and potential fatality from cardiac arrest
Uncontrolled cell venting releasing HF and CO, deflagration, structural fire spreading to adjacent racks within minutes
Ventricular fibrillation, deep tissue burns at entry and exit points, and cardiac arrest from sustained DC contact
Delayed shock injury during enclosure entry causing severe burns and fatal arrhythmia even after lockout completion
Severe respiratory tract burns, pulmonary oedema, systemic fluoride poisoning, and delayed cardiac arrest within hours
Electrocution of upstream network workers, equipment destruction, regulatory breach of network connection agreement
Lumbar disc injury, crush injury to hands and feet, and dropped-module short-circuit triggering thermal event
Control measures
Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.
- 1Elimination — Complete all module installation, busbar torquing and BMS firmware loading in a fully de-energised state before any DC string is closed.
- 2Elimination — Remove all non-essential personnel from the BESS enclosure during first energisation and conduct remote sequence start from a designated safe observation point.
- 3Substitution — Substitute manual rotary DC isolators with motorised remote-operated DC contactors rated to AS 60947.3 to remove the operator from the arc-flash boundary.
- 4Engineering — Install permanent arc-flash relief vents, deflagration panels and gas detection (H2, CO, HF) interlocked to fire suppression per AS/NZS 5139:2019 Section 3.
- 5Engineering — Use insulated DC measurement probes rated CAT IV 1500 V DC and a calibrated insulation resistance tester to verify isolation before any conductor contact.
- 6Administrative — Implement a written permit-to-work for each energisation step, signed by the commissioning engineer and a second competent witness as required by the NSW BESS CoP 2024.
- 7Administrative — Conduct a documented pre-start arc-flash risk assessment calculating incident energy in cal/cm² and define the restricted approach boundary in the SWMS.
- 8Administrative — Restrict commissioning to A-grade electricians holding battery storage endorsement and verify competency records before sign-on to this SWMS.
- 9PPE — Provide arc-rated coveralls, balaclava and face shield matched to the calculated incident energy (minimum ATPV 40 cal/cm² for string voltages above 600 V DC).
- 10PPE — Issue Class 0 insulating gloves with leather over-gloves, dielectric boots, and supplied-air respirators for any task within 2 m of a venting or suspected-faulted cell.
Applicable Codes of Practice
Specifies enclosure, ventilation, signage and commissioning test sequence; Section 3 mandates fire separation and gas management for the commissioning phase.
Imposes permit-to-work, exclusion zone, emergency response and notification duties on the PCBU during BESS commissioning and first energisation activities.
Clause 2.3 mandates isolation, verification of de-energisation and prospective fault current calculation before any energised work on the AC side of the inverter.
Defines safe approach distances, test-before-touch procedure and rescue arrangements that the SWMS must adopt for DC string work above ELV thresholds.
High-Risk Construction Work triggered
Charge acceptance testing can drive a lithium-ion cell into thermal runaway, venting hydrogen, carbon monoxide and hydrogen fluoride into the enclosure — which is why gas detection is interlocked to fire suppression under AS/NZS 5139:2019 and supplied-air respirators are specified within 2 m of a venting or suspected-faulted cell.
DC string voltages routinely exceed 600 V and cannot always be fully isolated during commissioning verification, placing workers directly on energised conductors.
PCBU must prepare, consult workers on, and retain this SWMS for the duration of the work plus statutory record period; penalties for non-compliance are substantial and indexed annually under the prevailing WHS schedule.
Who this is for
- →Commissioning engineers on utility-scale BESS projects
- →A-grade electricians with battery storage endorsement
- →EPC contractors delivering grid-connected storage assets
- →Site supervisors managing BESS energisation and grid connection
What you receive
- ✓Editable DOCX template — Microsoft Word compatible
- ✓State-specific WHS legislation schedule (NSW/VIC/QLD/SA/WA/TAS/NT/ACT)
- ✓Hazard register with risk ratings + hierarchy-of-control mapping
- ✓Worker sign-on register, pre-start checklist, and incident escalation flow
Worked example
On a 20 MW / 40 MWh containerised BESS commissioning at a regional substation, the commissioning engineer convenes a pre-start brief at 06:30 with two A-grade electricians, the network representative and the site supervisor. The SWMS is projected on a tablet and each hazard reviewed against the day's scope: string-level insulation resistance testing on Racks 7 through 12, followed by first DC closure. The team identifies that Rack 9 had a module replaced overnight, so the SWMS-mandated additional control of extended IR testing and 30-minute thermal soak observation is added in the live amendments column. Arc-flash incident energy is recalculated as 18 cal/cm² at the combiner, confirming the issued 40 cal/cm² suite is appropriate. Each worker signs on, including the network representative who is briefed on the exclusion zone and the remote-operated contactor sequence. During energisation, the gas detector alarms briefly on Rack 11; the supervisor invokes the SWMS emergency response step, initiates remote trip, evacuates to the 25 m muster point and notifies the regulator. After investigation confirms a faulty sensor, the SWMS is re-reviewed, the false-alarm response is logged, and a toolbox amendment is added requiring sensor calibration verification before any future re-energisation attempt. The signed SWMS and amendment log are retained in the project commissioning file.
Related legislation
- WHS Act 2011 (model)
- WHS Regulation 2025
- AS/NZS 3000 — Electrical installations
Frequently asked questions
Is BESS commissioning high risk construction work?
Where it forms part of construction work on a site, yes, on two grounds under s291: work on or near energised electrical installations, because DC string voltages routinely exceed 600 V and cannot always be fully isolated during verification, and work involving a risk of fire or explosion, because charge acceptance testing can drive a cell into thermal runaway with vented flammable gas. Either makes a SWMS mandatory under s299 before commissioning starts. Alongside it, AS/NZS 5139:2019 and the NSW BESS Code of Practice require documented commissioning procedures, isolation verification and a permit-to-work system in their own right.
Does this cover stranded energy after isolation?
Yes — it is listed as its own high priority hazard, because lockout completion is exactly when crews relax. Capacitor banks and the inverter DC link hold charge after isolation, so an enclosure entry that follows a correct lockout can still deliver a fatal shock. The control is verification rather than assumption: insulated DC measurement probes rated CAT IV 1500 V DC and a calibrated insulation resistance tester used to prove dead before any conductor is touched, following the test-before-touch procedure in AS/NZS 4836. Parallel-connected strings that cannot be fully de-energised are treated as live work throughout.
What arc-flash PPE does the SWMS specify?
PPE matched to a calculated incident energy, not a fixed suite. A documented pre-start arc-flash risk assessment calculates incident energy in cal per square centimetre and defines the restricted approach boundary in the SWMS, and arc-rated coveralls, balaclava and face shield are selected against it, with a minimum ATPV of 40 cal per square centimetre for string voltages above 600 V DC. The worked example recalculates 18 cal per square centimetre at the combiner and confirms the issued 40 cal suite covers it. Better still is removing the operator from the boundary: motorised remote-operated DC contactors to AS 60947.3 replace manual rotary isolators.
What happens if a gas detector alarms during first energisation?
The emergency response step runs immediately — remote trip, evacuate to the muster point, notify — and it runs before anyone decides whether the alarm is real. Hydrogen, carbon monoxide and hydrogen fluoride detection is interlocked to fire suppression under AS/NZS 5139:2019, and a venting cell releases hydrogen fluoride that causes respiratory burns, pulmonary oedema and systemic fluoride poisoning with a delayed cardiac effect. Supplied-air respirators are specified for any task within 2 m of a venting or suspected-faulted cell. In the worked example the alarm turns out to be a faulty sensor, and the response is still logged and a calibration check added before re-energisation.
Who is permitted to carry out commissioning?
A-grade electricians holding battery storage endorsement, with competency records verified before they sign on. Each energisation step runs under a written permit-to-work signed by the commissioning engineer and a second competent witness, and non-essential personnel are cleared from the enclosure with the sequence started remotely from a designated safe observation point. Anyone else on site during energisation — including a network representative — is briefed on the exclusion zone and signs on. You receive an editable Microsoft Word DOCX bought once, to be made site specific for your array, string voltages and permit sequence.