AS/NZS 61439.2 is titled “Low-voltage switchgear and controlgear assemblies – Part 2: Power switchgear and controlgear assemblies.”

In simple terms, it sets out the rules for switchboards and control panels used in industrial and commercial environments. These aren’t the small distribution boards you see in a typical home. Instead, Part 2 covers:

• – Large commercial switchboards
• – Industrial motor control centres (MCCs)
• – Plant and facility main switchboards
• – Specialised assemblies used in infrastructure projects

If a switchboard is too big or complex to fall under the rules of Part 3 (which is for domestic and small commercial boards), then it defaults to Part 2.

Scope of the Standard

Part 2 applies to assemblies with:

• – Rated voltage up to 1,000 V AC
• – Rated voltage up to 1,500 V DC

It covers assemblies that may be:

• – Stationary or movable
• – With or without enclosures
• – For distribution, control, or conversion of electricity

What’s not included? Individual devices like motor starters or circuit breakers themselves. Those components have their own product standards. AS/NZS 61439.2 only applies to the complete assembly.

Why Was It Introduced?

The old AS/NZS 3439 standard was used for many years, but it had a few problems:

• – It wasn’t clear who was responsible for compliance – was it the switchboard builder, the component supplier, or the designer?
• – Testing requirements weren’t always standardised, which meant one builder might do things differently from another.
• – There was often confusion in project specifications.

AS/NZS 61439.2, together with Part 1, fixed those issues by:

• – Clearly defining roles and responsibilities
• – Introducing standardised verification methods
• – Aligning Australia and New Zealand with IEC international practices
• – Ensuring greater safety and reliability in switchboard manufacturing

Since May 2021, compliance with AS/NZS 61439 has been mandatory. The transition period is over—AS/NZS 3439 can no longer be used.

The Link Between Part 1 and Part 2

It’s important to understand that Part 1 (General Rules) always applies. Part 2 doesn’t stand alone—it works hand-in-hand with Part 1.

Think of it like this:

• – Part 1 = the foundation. It sets the general requirements that apply to all assemblies.
• – Part 2 = the specific rules for power switchgear and controlgear assemblies.

So if you’re building or specifying an industrial switchboard, you must comply with both Part 1 and Part 2.

Key Requirements in AS/NZS 61439.2

1. Design Verification (Clause 10)

One of the biggest changes in the 61439 series is design verification. Clause 10 of Part 2 lists 13 characteristics that must be verified for every design, including:

• – Strength of materials and parts – resistance to heat, corrosion, and impact
• – Degree of protection (IP rating) – meeting dust and water ingress claims
• – Clearances and creepage distances – preventing flashover and arcing
• – Temperature-rise limits – ensuring the board doesn’t overheat under full load
• – Short-circuit withstand strength – proving the assembly can handle fault currents
• – Mechanical operation – reliability of doors, interlocks, and moving parts

Verification can be done by test, calculation, or comparison with a previously verified design.

2. Routine Verification

While design verification proves that the design is compliant, routine verification ensures each individual assembly is built correctly.

This includes:

• – Inspecting materials and construction
• – Checking wiring and connections
• – Verifying markings and labels
• – Testing functions and interlocks

Every single switchboard must undergo routine verification before it leaves the workshop.

Arc Fault Containment – Annex ZD

A unique feature of AS/NZS 61439.2 is Annex ZD, which deals with internal arc fault containment.

While not mandatory, many utilities, mining companies, and data centres require arc fault testing. This involves deliberately creating an arc fault inside a switchboard and checking that:

• – Doors stay shut
• – No parts are ejected dangerously
• – Flames don’t spread outside the enclosure
• – Operators standing in front remain safe

Arc fault containment has become a hot topic in recent years, especially in high-energy installations. Annex ZD gives clear guidance for testing to IEC TR 61641.

Part 2 vs Part 3

Here’s a quick way to remember the difference:

• – Part 3 = small distribution boards for “ordinary persons” (like domestic switchboards). Max current 250 A, outgoing circuits ≤ 125 A.
• – Part 2 = everything else. If it doesn’t meet the limits of Part 3, it falls under Part 2.

That means most commercial, industrial, and infrastructure switchboards must comply with Part 2.

Who Needs to Care About AS/NZS 61439.2?

This standard affects almost everyone in the electrical industry:

• – Consultants and specifiers – need to ensure tender documents call up compliance with AS/NZS 61439.2.
• – strong>Switchboard builders – must keep design verification records and carry out routine verification.
• – Contractors and electricians – need to understand the differences when ordering or installing switchboards.
• – Asset owners – benefit from safer, more reliable switchboards that meet international best practice.

Benefits of AS/NZS 61439.2

So, what’s in it for you? Here are the key benefits:

• – Improved safety – switchboards are proven to withstand faults and heat.
• – Consistency – standardised testing means less variation between manufacturers.
• – Clear responsibilities – the standard defines who is responsible for what.
• – Future-proofing – aligns with global IEC standards, keeping Australia and New Zealand in step with international practice.