Battery arc flash and class
Battery DVC, hazard class, arc flash energy and PPE level.
Reads AS/NZS 5139:2019. Tables checked 1 Oct 2026.
Try a job 4
Each job fills in example values. Replace them with your values.
- Check a 48 V home battery's arc flashThe energy, PPE level and home limit for a 48 V lithium battery.
- See what inter-string fuses saveThe same 48 V battery with the arc cleared in a tenth of a second.
- Class a lead acid bank in a shedA 24 V lead acid bank in a battery room away from the house.
- Class a high voltage home batteryThe decisive voltage class and energy of a pre-assembled lithium battery.
Inputs
Worked example with the default inputs. The live calculator replaces it when the page loads.
- Chemistry
- Lithium ion
- Pre-assembled to the Best Practice Guide, or a V0-rated case
- No
- Battery voltage, highest d.c.
- 51.2 V
- Bolted fault current at the work
- 6 kA
- Arcing time
- 2 s
- Working distance
- 45 cm
- Housing
- Battery enclosure or cabinet (factor 3)
- Location
- In or at a home
Arc flash incident energy
4.55cal/cm²
- PPE level
- Level 2
- Consequence level
- Moderate
- Arc flash boundary
- 876mm
- Decisive voltage class
- A
- Fire hazard level
- Level 1
This result is a design aid. Verify it against the current standard.
Calculation steps
- Decisive voltage classA
AS/NZS 5139:2019 Table 3.2
- Fire hazard levelLevel 1
AS/NZS 5139:2019 Table 3.1
- Hazards namedElectrical, energy, mechanical, explosive gas and toxic fume
AS/NZS 5139:2019 Table 3.1
- Arcing current, half the bolted fault current3kA
AS/NZS 5139:2019 Eq 3.2.4(2)
- Multiplying factor3
AS/NZS 5139:2019 Cl 3.2.4.3
- Arc flash incident energyResult4.55cal/cm²
AS/NZS 5139:2019 Eq 3.2.4(1)
- Arc flash boundary876mm
AS/NZS 5139:2019 Eq F.4
- PPE levelLevel 2
AS/NZS 5139:2019 Table 3.3
- Consequence levelModerate
AS/NZS 5139:2019 Table 6.1
About this calculator
How this is calculated
AS/NZS 5139 asks for a battery system to be classed before it is installed: which hazards its chemistry carries, which voltage class it is in, and how much energy an arc at its terminals would release. This tool works all three from a few inputs and reads the tables that follow from them.
The hazards and the fire hazard level come from the chemistry. Lithium ion is fire hazard level 1, lead acid and nickel alkaline level 2. A note to the table lifts the level for pre-assembled lithium equipment that meets the industry Best Practice Guide, and for lead acid or nickel alkaline in cases rated V0. The decisive voltage class comes from the battery's highest d.c. voltage.
The arc flash energy uses the standard's equation. It multiplies the battery voltage, the arcing current, the arcing time divided by the working distance squared, and a factor for where the arc is: at least 3 in an enclosure and 1.5 in a room. The arcing current is half the bolted fault current. The working distance is 45 cm at most. The arcing time is 2 s where the protective device's time is not known, or where the work is on its battery side. The boundary is the distance where the energy falls to 1.2 cal/cm². The appendix tables are this equation at 45 cm and a factor of 3, and a test runs every printed row through it.
The energy then sets the PPE level, the consequence level for the risk assessment, and, in a home or outside one, the limits on where the system may go.
| Step | Table or clause | What it decides |
|---|---|---|
| Hazards and fire hazard level | AS/NZS 5139 Table 3.1 | What the chemistry carries |
| Decisive voltage class | AS/NZS 5139 Table 3.2 | DVC-A, B or C from the d.c. voltage |
| Arcing current and energy | AS/NZS 5139 Cl 3.2.4 | The incident energy at the working distance |
| Arc flash boundary | AS/NZS 5139 Equation F.4 | Where the energy falls to the boundary level |
| PPE level | AS/NZS 5139 Table 3.3 | The arc-rated clothing level |
| Consequence level | AS/NZS 5139 Table 6.1 | The consequence for the risk assessment |
| Home and outdoor limits | AS/NZS 5139 Cl 6.3.2.3 | Where the system may go at that energy |
Worked examples
- A 48 V lithium home battery with 6 kA at its terminals releases 4.27 cal/cm² over 2 s, PPE Level 2. Above 4 cal/cm² in a home it needs a dedicated room or fire hazard level 1.
- The same battery with inter-string fuses clearing in 0.1 s releases 0.21 cal/cm², PPE Level 1.
- A 24 V lead acid bank in a battery room away from the house releases 2.13 cal/cm² at a factor of 1.5, PPE Level 1.
- A 204.8 V pre-assembled lithium home battery with 9 kA is DVC-C and releases 27.31 cal/cm², PPE Level 4.
- A 350 V system with 15 kA in a plant room releases 77.78 cal/cm², so it fails: no PPE level applies above 40.
Limits
The tool works the energy at one point with one arcing time. It does not find the bolted fault current, which comes from the battery maker or the home battery tool, or a fuse's clearing time at that current, which comes from its curve. It does not grade the likelihood side of the risk matrix.
The tool reads the 2019 edition as published. Amendment 1 (2025) is not on hand, so check any change it makes before relying on a figure.
See also: Home battery, Arc flash and Battery.
Questions
Each answer describes what this tool calculates. The result is a design aid. Verify against the current standard.
How is battery arc flash energy worked out?
AS/NZS 5139 Cl 3.2.4 multiplies the battery voltage, the arcing current, the arcing time over the working distance squared, and a factor for the enclosure. The arcing current is half the bolted fault current.
What arcing time should I use?
Use 2 s where the protective device's operating time is not known, or where the work is on the battery side of it. On the other side, use the device's time at that fault current. A fuse between strings cuts the time and the energy.
What is the decisive voltage class of a battery?
AS/NZS 5139 Table 3.2 classes a d.c. battery as DVC-A up to 60 V, DVC-B up to 120 V, and DVC-C above. A DVC-B or DVC-C system is a low voltage installation under AS/NZS 3000.
Can a home battery be over 4 cal/cm²?
Yes, below 40 cal/cm². Above 4 it goes in a dedicated room or enclosure not attached to a building with habitable rooms, or meets fire hazard level 1, and not inside or against such a building. Inter-string protection can bring it down.
Which PPE level do I need?
AS/NZS 5139 Table 3.3 sets the PPE level by the energy: level 1 up to 4 cal/cm², level 2 up to 8, level 3 up to 25 and level 4 up to 40. Above 40 no PPE level applies.
Clauses and tables this tool reads
- AS/NZS 5139:2019 Cl 3.2.4Battery arc flash energy
- AS/NZS 5139:2019 Cl 3.2.4.2.3Arc duration for a battery
- AS/NZS 5139:2019 Cl 3.2.4.3Arc flash multiplying factor
- AS/NZS 5139:2019 Cl 6.3.2.3Arc flash limits for a home battery
- AS/NZS 5139:2019 Eq 3.2.4(1)Battery arc flash incident energy
- AS/NZS 5139:2019 Eq 3.2.4(2)Battery arcing current
- AS/NZS 5139:2019 Eq F.4Battery arc flash boundary
- AS/NZS 5139:2019 Tables 3.1 to 3.3, 6.1 and F.1 to F.4Battery system hazard classes, decisive voltage class, arc flash energy, PPE level and consequence level
Every clause and table, with how each was verified
Tables last checked on 1 Oct 2026.
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