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Switchboard compliance explained: a plain-English guide to AS/NZS 61439
What the standard requires, what a compliant board actually means, and what to ask for when you buy a switchboard, MCC or control panel.
A switchboard is only as safe as the design and build behind it. In Australia, low-voltage switchboards, MCCs and control panels are built to AS/NZS 61439. This guide explains what that standard requires, what compliant actually means, and what to ask for when you buy a board.
What AS/NZS 61439 covers
AS/NZS 61439 applies to low-voltage assemblies: main switchboards, distribution boards, motor control centres and control panels. Part 1 sets the general rules and Part 2 covers power switchgear and controlgear assemblies, with other parts for specific board types.
It replaced AS/NZS 3439 and its "type-tested" and "partially type-tested" categories. Instead, every board must have design verification (proof the design works) and routine verification (proof this particular board was built correctly).
Who is responsible
- Original manufacturer: the company whose system or enclosure design was originally developed and verified, often by testing
- Assembly manufacturer: the switchboard builder who designs or adapts the board, completes the assembly and carries out routine verification. They take responsibility for the finished board.
In practice, when you buy a board, your switchboard builder is the one who has to show it complies.
Design verification in plain English
Design verification proves the board's design will do its job safely for its whole life. AS/NZS 61439.1 lists the characteristics that must be verified, including:
- Temperature rise: the board can carry its rated current without overheating, verified by test, by comparison with a tested design, or by calculation within strict limits
- Short-circuit withstand: busbars, supports and devices survive the fault current available on site. This can't be verified by assessment alone.
- Dielectric properties: insulation and clearances withstand the voltages the board will see
- Protective circuit: earthing and the protective conductor can carry fault current
- Construction: enclosure strength, IP rating, mechanical operation, and resistance to heat and corrosion
Verification can be done by testing, by comparison with a tested reference design, or by assessment (calculation and design rules), depending on the characteristic.
Routine verification
Every individual board is checked before it leaves the workshop: wiring and terminations, torque on connections, clearances, operation of devices and interlocks, insulation and protective circuit checks. The results are recorded and supplied with the board.
Larger boards: extra requirements
AS/NZS 3000 adds requirements for larger switchboards, generally from 800 A per phase upwards, including forms of separation (internal segregation between busbars and functional units) and arc fault mitigation. For main switchboards connected to the network, the local distributor's service and installation rules also apply to metering, isolation and the main switch.
What to ask for when you buy a board
- Compliance stated in writing: supplied compliant with AS/NZS 61439, not "built to" an older standard.
- Ratings on the drawings: rated current, rated short-time or conditional short-circuit current, IP rating and form of separation.
- Design verification records against Annex D of AS/NZS 61439.1, or confirmation of the verified system the board is built on.
- A routine verification record for your specific board.
- As-built drawings and a labelled, documented board, ready for future maintenance and changes.
Common problems we find
- Old boards modified over the years with no one checking the busbar or enclosure ratings
- Breakers or contactors substituted with a different brand without checking the verified design
- Boards with no stated short-circuit rating, installed where the fault level is higher than they can handle
- Overcrowded enclosures that run hot in summer
- No drawings, labels or verification records
How AMC helps
AMC designs and builds main switchboards, distribution boards, MCCs and control panels in our Griffith workshop, from small control boards to 1000 A main distribution boards. Every board is verified and tested before it leaves, supplied with drawings and records, and installed by our own crew if you need it. We deliver across the Riverina and Australia-wide.
This guide is general information to help you understand the standard. It is not legal advice, and requirements for a specific board depend on its design and installation.
FAQs
Common questions about switchboard compliance
What is AS/NZS 61439?
It is the Australian and New Zealand standard for low-voltage switchgear and controlgear assemblies, which covers switchboards, MCCs, distribution boards and control panels. It replaced the old AS/NZS 3439 type-tested and partially type-tested approach with design verification and routine verification.
Is my switchboard builder responsible for compliance?
Yes. Under AS/NZS 61439 the assembly manufacturer, the business that builds and finishes the board, takes responsibility for the completed assembly, including its design verification and the routine verification of each board.
What should I ask for when I buy a switchboard?
Ask for the board to be supplied compliant with AS/NZS 61439, with design verification records against Annex D of AS/NZS 61439.1, a routine verification record for your board, and the rated current, short-circuit rating, IP rating and form of separation stated in writing.
Does IP rating or size change whether 61439 applies?
No. Every low-voltage assembly needs to comply, whatever its size or IP rating. Larger boards also pick up extra requirements under AS/NZS 3000, such as forms of separation and arc fault mitigation.
Can components be swapped for another brand?
Only within the rules. A substituted device has to be equal to or better than the one in the verified design, and the substitution has to be covered by the design verification. Swapping breakers on the fly without checking can invalidate a board's verification.
Do you build and test boards in-house?
Yes. AMC designs, builds and tests switchboards, MCCs and control panels in our Griffith workshop, and supplies the verification records with the board.
Next step
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