Changes to the Battery Standard
Amendment 1 to AS/NZS 5139:2019 introduces updates to battery energy storage system installation requirements. This advisory explains the key changes and how to comply.
| Note | 1/2026 |
| Date issued | January 2026 |
| Last updated | 3 March 2026 |
| For | Licensees / contractors / the electrical industry |
| Issued by | Building Commission NSW Electrical Compliance Team |
| Scope | Applies to all of NSW |
Purpose
The purpose of this advisory note is to inform industry of changes introduced under Amendment 1 to AS/NZS 5139:2019 Battery Standard and to assist electricians in complying with the updated requirements for battery energy storage system installations.
Issue
Amendment 1 to AS/NZS 5139:2019 was published on 19 December 2025 and is now mandatory. Any battery installation that does not meet the updated requirements may not comply with the Standard.
References
- AS/NZS 5139:2019 Amd 1:2025
Updates in Amendment 1
Amendment 1 introduces updates and clarifications across a number of clauses. Electricians should review the amended standard in full.
Definitions
Some definitions have been updated and new definitions have been introduced.
Electricians should review Clause 1.3 - Terms and definitions to ensure the correct terminology is applied when designing and installing battery systems.
Installation diagrams
Typical Battery Energy Storage Systems (BESS) installation diagrams have been revised and new figures have been added.
Installations should reflect the updated diagrams where applicable.
Location, clearances and safe egress
Changes have been made to location and clearance requirements.
Battery systems may now be installed within 600mm of an opening, provided the opening is wider than 900mm, such as a garage door.
Windows and ventilation in restricted locations
The standard now clarifies how windows and building ventilation are to be treated when a battery system is installed in a restricted location.
Electricians should check these requirements before finalising the installation location.
Associated appliances and equipment
Inverters are now considered as an associated appliance and allowed within the restricted location.
Barriers to habitable rooms
Requirements for exempt materials used as a barrier to habitable rooms have been revised.
Exempt materials must now have a minimum thickness of 6mm.
Overcurrent protection for battery system in a paralleled pre-assembled battery system
Overcurrent protection devices must have a kA rating that matches or exceeds the combined fault current of the paralleled battery systems.
Building materials within 1 metre
New requirements apply to building materials installed within 1 metre of a battery system that is categorised as a chemical hazard.
Safety Data Sheets (SDS)
The amendment clarifies requirements for Safety Data Sheets (SDS).
- A physical copy of the SDS must be provided.
- SDS must be protected from damage or degradation, for example stored in a sealed, durable clear pouch.
New appendix
Appendix I has been introduced to explain how to calculate cell short-circuit current.
Where the changes appear in the amended standard
The following clauses, figures, appendix and bibliography references are updated or introduced in Amendment 1.
Updated clauses
| Clause | Title | Topic |
|---|---|---|
| 1.3 | Terms and definitions | 1. Scope and general |
| 3.2.3.3 | Battery system prospective fault current / short circuit current | 3. Battery energy storage system hazards |
| 4.2.2.1 | General - Location | 4. Pre-assembled integrated BESSs - Installation, commissioning and documentation |
| 4.2.2.2 | Restricted locations | 4. Pre-assembled integrated BESSs - Installation, commissioning and documentation |
| 4.2.4.2 | Barrier to habitable rooms | 4. Pre-assembled integrated BESSs - Installation, commissioning and documentation |
| 4.2.5 | Pre-assembled integrated BESS room requirements | 4. Pre-assembled integrated BESSs - Installation, commissioning and documentation |
| 5.2.2.1 | General - Location | 4. Pre-assembled battery systems - Installation, commissioning and documentation |
| 5.2.2.2 | Restricted locations | 4. Pre-assembled battery systems - Installation, commissioning and documentation |
| 5.2.4.2 | Barrier to habitable rooms | 4. Pre-assembled battery systems - Installation, commissioning and documentation |
| 5.3.1.2.1 | General - Overcurrent protection from battery system | 5. Pre-assembled battery systems - Installation, commissioning and documentation |
| 5.3.1.3.8 | BESS with multiple PCEs | 5. Pre-assembled battery systems - Installation, commissioning and documentation |
| 6.3.6.4 | Additional requirements for enclosures and rooms | 6. Battery systems and BESSs not covered by Sections 4 and 5 - Installation, commissioning and documentation |
| 7.2 | Requirements for signs and labels | 7. Labels and safety signage |
| 7.7 | Safety data sheet (SDS) | 7. Labels and safety signage |
| 7.8 | Explosive gas hazard | 7. Labels and safety signage |
| 7.9 | Toxic fume hazard | 7. Labels and safety signage |
| 7.10 | Chemical hazard | 7. Labels and safety signage |
| 7.11 | Arc flash | 7. Labels and safety signage |
Updated or new figures
| Figure | Description |
|---|---|
| 2.11 | Typical BESS installation diagram: multiple BESSs each with single battery system connected to single PCEs |
| 2.12 | Typical BESS installation diagram: multiple BESSs each with single battery system connected to multiple PCEs |
| 4.1A | BESS egress clearance in a corridor, hallway or lobby |
| 4.1B | BESS clearance to doors and openings |
| 4.1C | Clearance from restricted locations – front view |
| 4.1D | Clearance from restricted locations – side view |
| 4.2A | Minimum unimpeded access to a pre-assembled integrated BESS within a room |
New appendix
| Appendix | Description |
|---|---|
| Appendix I | Calculation of cell short circuit current |
Updated bibliography
| Standard | Title |
|---|---|
| AS 1319 | Safety signs for the occupational environment |
| AS 2676.1 | Installation, maintenance, testing and replacement of secondary batteries in buildings – Part 1: Vented cells |
| AS 2676.2 | Installation, maintenance, testing and replacement of secondary batteries in buildings – Part 2: Sealed cells |
Contact Electrical Compliance Team
This advisory note has been approved for issue by the Electrical Compliance Team.
Information contained within this document is current at the time it was last updated and refers to codes and standards current at the time of writing.
Building Commission NSW disclaims any liability (including for negligence) to any person in respect of anything done, or not done, by that person in whole or partial reliance on any of the information in this advisory note.
For more information, please email: electricalcompliance@customerservice.nsw.gov.au