As most solar installers should be aware, the new battery standard AS/NZS 5139: Safety of battery systems for use with power conversion equipment is now published. As this standard is different to most other electrical standards, it might be a challenge to get your head around. Here are some thoughts to help you get started.

Why is AS/NZS 5139 different to other standards?

We all know electricity can be dangerous, with the potential to cause death to people and animals and damage property if not properly handled. Most electrical standards are about mitigating the risk of electricity to an acceptable level. AS/NZS 5139 is more complex because batteries have a diversity of risks (depending on the chemistry of the battery) that may include chemical, fire, explosive, toxic fumes and mechanical hazards.

While these risks are generally low, dealing with the hazards associated with battery chemistries is new to most sparkies, and this is the first reason why AS/NZS 5139 will take some getting used to.

The second reason is that the hazards of one battery chemistry can be very different to another. For example, many experienced off-grid installers will know that both gel and flooded lead-acid batteries produce hydrogen in normal operation and under fault condition. Hydrogen is an explosive gas, so sources of ignition (like switches and inverters) are not permitted where the hydrogen could vent.

But as only some batteries have explosive gas hazards, it would be very restrictive if AS/NZS 5139 made all battery installations protect against this risk. As a workaround, AS/NZS 5139 directs installers to refer to the battery manufacturer’s instruction manual for information on the hazards associated with the brand of battery they are installing. While this approach makes sense, it means that installers will need to be across the standard as well as the fine print of the products they are installing.

This structure of AS/NZS 5139 is also a little different to many of the other standards we work with and a potential cause of confusion. I find it helps to think of AS/NZS 5139 as basically three standards in one. There are seven sections: sections 1, 2, 3 and 7 are generic to all batteries, while you follow either section 4, 5 or 6 depending on whether or not the battery conforms to the Best Practice Guide: Battery Storage Equipment (BPG).

What is the Best Practice Guide?

From the perspective of an electrician following AS/NZS 5139, the BPG can be thought of as if it were a product standard. Batteries that conform to the BPG have proven levels of safety during the manufacturing processes and so require less onerous installation standards.

If you are installing a battery with an in-built inverter that conforms with the BPG – such as a Tesla, Sonnen or Enphase battery – you need to follow Section 4, along with the other generic sections. If you are installing a battery without an in-built inverter but which still conforms with the BPG – such as a LG Chem or BYD battery – you can ignore section 4 and 6 and pay attention to Section 5.

I know some off-grid installers who still recommend the tried and tested lead-acid technology. If this is you, or you sell anything else not conforming to the BPG, Section 6 is what you need to be across.

If you are new to installing batteries, I would suggest a good place to start is with a battery that conforms with the BPG, because sections 4 and 5 are much easier to follow than Section 6. To view a list of batteries that conform with the BPG, go to the Products section of the CEC’s website.

Blanket rules versus variable rules

The consensus of the committee that wrote AS/NZS 5139 was that there needs to be a set of blanket rules, regardless of which battery chemistry is being installed. Whether your battery falls into section 4, 5 or 6, these rules are the bare minimum that electricians need to follow.

The clauses that require a fire-proof barrier between a battery and a wall adjoining a habitable room in certain circumstances is an example of one of the blanket rules. For more information on this rule, I would recommend watching the CEC Toolbox Talk AS/NZS 5139: The cement sheet rule.

There are other rules that are variable depending on the type, brand and model of battery being installed. If the battery you have chosen has no extra hazards, there may be no other variable rules beyond the blanket rules. For example, if you were considering installing a lithium battery that conforms with the BPG, there are no extra fire protection rules you need to follow other than the cement sheet rule. However, if you were to choose a lithium battery that doesn’t conform with the BPG, you would need to follow both the blanket rules and the variable rules for that chemistry.

In practice, working with batteries that are on the CEC’s approved battery list is more straightforward, and this provides an additional layer of protection to help keep low-quality products out of the market.

When is AS/NZS 5139 mandatory?

AS/NZS 5139 will not become mandatory until the Wiring Rules (AS/NZS 3000) reference it or individual jurisdictions choose to amend their regulations. The Wiring Rules are currently going through an amendment process and are expected to be published in the first half of 2020.

The CEC’s Battery Installation Guidelines were developed to plug a gap while the industry waited for an up-to-date battery standard. Once AS/NZS 5139 is made mandatory, the CEC’s current Battery Installation Guidelines will be superseded by the standard.

James Patterson is the technical support leader at the Clean Energy Council.