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Battery arc flash and class

Battery DVC, hazard class, arc flash energy and PPE level.

AS/NZS 5139

Reads AS/NZS 5139:2019. Tables checked 1 Oct 2026.

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Each job fills in example values. Replace them with your values.

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

  1. Decisive voltage classA

    AS/NZS 5139:2019 Table 3.2

  2. Fire hazard levelLevel 1

    AS/NZS 5139:2019 Table 3.1

  3. Hazards namedElectrical, energy, mechanical, explosive gas and toxic fume

    AS/NZS 5139:2019 Table 3.1

  4. Arcing current, half the bolted fault current3kA

    AS/NZS 5139:2019 Eq 3.2.4(2)

  5. Multiplying factor3

    AS/NZS 5139:2019 Cl 3.2.4.3

  6. Arc flash incident energyResult4.55cal/cm²

    AS/NZS 5139:2019 Eq 3.2.4(1)

  7. Arc flash boundary876mm

    AS/NZS 5139:2019 Eq F.4

  8. PPE levelLevel 2

    AS/NZS 5139:2019 Table 3.3

  9. 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.

StepTable or clauseWhat it decides
Hazards and fire hazard levelAS/NZS 5139 Table 3.1What the chemistry carries
Decisive voltage classAS/NZS 5139 Table 3.2DVC-A, B or C from the d.c. voltage
Arcing current and energyAS/NZS 5139 Cl 3.2.4The incident energy at the working distance
Arc flash boundaryAS/NZS 5139 Equation F.4Where the energy falls to the boundary level
PPE levelAS/NZS 5139 Table 3.3The arc-rated clothing level
Consequence levelAS/NZS 5139 Table 6.1The consequence for the risk assessment
Home and outdoor limitsAS/NZS 5139 Cl 6.3.2.3Where the system may go at that energy

Worked examples

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

Every clause and table, with how each was verified

Tables last checked on 1 Oct 2026.

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