Where You Can't Put a Battery: AS/NZS 5139:2019 Location Rules for Commercial BESS
Battery energy storage systems are treated as sources of ignition under AS/NZS 5139:2019. The standard sets out specific locations where a BESS cannot be placed and those restrictions carry real consequences for commercial fitouts and rooftop solar upgrades.
A commercial tenant wants to add battery storage to an existing rooftop solar system. The obvious location a plant room off the main corridor, or a cupboard space in the ceiling seems practical and out of the way. But under AS/NZS 5139:2019, both of those locations may be prohibited. The standard was not written to be inconvenient; it was written because the consequences of a battery fire in the wrong location are severe.
Building and Energy's Electrical Focus Issue 4 (February 2021) sets out the reasoning directly: "As the BESS is considered to be a source of ignition, the requirements within this standard ensure that the unit is adequately protected from external influences that may cause damage to the BESS and to ensure that external ignition sources do not pose a risk to the BESS."
AS/NZS 5139:2019 was published on 11 October 2020 and sets out general installation and safety requirements for BESS. For anyone planning commercial battery storage in Western Australia, understanding its location restrictions is not optional.
Passageways, Exits, and Escape Routes
The prohibition most likely to affect commercial fitout planning concerns escape routes. The standard prohibits installation within a passageway, walkway, exit, or escape or evacuation route. It also prohibits installation underneath or below entrance and exit walkways, staircases, evacuation and escape routes and passageways, whether external or internal to the building.
The notes in the standard explain the logic: smoke generated from a burning BESS may be noxious and therefore impede a person from utilising an escape route directly above the BESS. In timber framed structures, structural damage will occur initially above a fire and may affect the structural integrity of the escape route above. These requirements apply to all structures regardless of the construction method or materials.
The restriction also extends to proximity to exits: a BESS cannot be installed within 600mm from an exit that has an opening 900mm or less.
Roofs, Ceiling Spaces, and Wall Cavities
Three building locations that might seem attractive for concealing or weather-protecting a BESS are specifically restricted. The standard prohibits installation on roofs, unless the roof is accessible via a permanently installed or fixed staircase or access ladder. It prohibits installation within ceiling spaces. It prohibits installation set into wall cavities, with a narrow exception: a BESS installed within a separate non-combustible enclosure or housing that is recessed into and entirely sealed to the wall cavity is not considered recessed into the wall cavity.
For a standard commercial building where wall cavities are not accessible as enclosed fire-rated compartments, these three locations are effectively unavailable for BESS placement.
Windows, Vents, and Airflow Openings
The standard also sets exclusion zones around openings to habitable rooms. A BESS must not be installed within 600mm horizontally and 900mm below an opening window to a habitable room, or vents including mechanical, electrical or other ventilation openings to habitable rooms. In commercial buildings where office spaces, meeting rooms, or occupied areas adjoin plant spaces, this requirement can significantly restrict the available footprint for battery installation.
The Restricted Zone Around the BESS Itself
Beyond where a BESS may not be placed, the standard creates a restricted zone surrounding an installed unit. Electrical appliances not associated with the BESS may not be located closer than 600mm horizontally nor 900mm above the BESS. This includes heat pumps, air-conditioning equipment and associated control gear, hot water cylinders, motors and control gear, stoves and hotplates, and stationary appliances as defined by AS/NZS 3000. Solar inverters supplying the BESS are excluded from this restriction.
What This Means for Commercial Projects
The practical consequence of these restrictions is that BESS location cannot be treated as an afterthought in commercial building design or fitout. A position that works architecturally and mechanically may still be non-compliant under AS/NZS 5139:2019 if it sits above an escape route, in a ceiling void, or too close to an exit door or ventilation opening.
For builders and facility managers planning commercial solar and battery installations in Western Australia, reviewing the AS/NZS 5139:2019 location requirements before committing to a placement is far more efficient than discovering a prohibited location during inspection. Leemont works through these requirements as part of the design and installation process for commercial BESS projects get in touch if you would like to discuss a specific site.
