Switchboards and the Implementation of AS/nZS 61439

SWITCHBOARDS

AND THE IMPLEMENTATION OF AS/NZS 61439

In MAY 2021, THe neW AS/nZS 61439 SeRIeS OF STAnDARDS BeCAMe THe OnLY ACCePTABLe STAnDARD FOR SWITCHBOARD SPeCIFICATIOn. TO SuPPORT MeMBeRS WITH ITS IMPLeMenTATIOn, neCA ReCenTLY RAn A WeBInAR, WHICH InCLuDeD A DeTAILeD Q&A DISCuSSIOn. HeRe ARe SOMe OF THe KeY QueSTIOnS OuR PAneL ADDReSSeD.

Do the new requirements apply to all switchboards or is there a minimum current limit?

AS/nZS 61439 compliance is mandated in Amendment 2 for assemblies rated greater than 10kA and above, or for assemblies having more than 125A of connected load per phase. This applies regardless of whether or not AS/nZS 61439 is specified by the client/consultant.

If a tender was submitted prior to May 2021, can the switchboard still be manufactured to AS/NZS 3439?

no. The new standard applies to switchboards that are being energised from May 2021 onwards, regardless of the tender date. This may vary in certain jurisdictions.

If you add a Circuit Breaker (CB) to an existing switchboard, how can it be verified?

Verification of the alteration includes the following:  Is the new CB installed as per the original manufacturer’s instructions, using verified means (busbars, support, size of enclosure etc). This is expected to require consultation with the switchboard builder.  Will the new load corresponding to the additional breaker overload the existing busbars? This can be verified by understanding the existing maximum demand on the switchboard section busbars, and seeing if the proposed additional load will exceed the rating of these busbars (as documented by the switchboard builder).  Will the additional load overload the main incoming breaker and/ or distribution breakers? As per the previous step, the existing load is required, and it must be verified that the additional load does not exceed the maximum rating of the supply breaker and/ or distribution breakers feeding the additional load (as documented by the switchboard builder).

What about repairs to existing switchboards?

If it’s an alteration, for example adding additional circuits or a new breaker, then it needs to be certified to AS/nZS 61439. The previous question addresses the verification process. If it’s a repair, then it is not required to comply with AS/nZS 61439.

Are there certified parties that can validate compliance?

Contractors are required to take responsibility for the compliance of their work. In the event of an installation’s failure, contractors may be found responsible if the installation was deemed non-compliant by the forensic inspector (who is expected to have access to qualified persons to assess the installation’s compliance). Parties that can validate compliance include supply authority and electrical inspectors, test stations and individual companies.

Does the testing have to be done at a test station?

no. It can be done on your own premises if you have the equipment to run the test. Then you will need to prepare a suitable report of the test, including evidence of the results achieved so they can be reviewed at a later stage, should any failure occur on site. note: Some consultants may choose to specify where verification tests are performed, for example a “nATA approved laboratory”. If testing is done outside the test station, calibration/verification of the test equipment is required. Also, an impartial third party should witness/verify the test.

We’ve been advised that a mechanical service switchboard (less than 250A/10kA) located in a plant room is classified as a DBO. Is this correct?

no. DBOs are assemblies intended to be used by “ordinary people”. AS/nZS 3000 clause K3.2 confirms the definition of ‘ordinary’ as being: “neither skilled nor instructed”.

It is assumed that on WORK premises, anyone using plant equipment is either skilled or instructed, otherwise they should nOT be using equipment that they have not been trained to use.

Can you expand on the electrician as the ‘assembly manufacturer’ for off-the-shelf/over-the-counter switchboards when there is no switchboard builder involved? Do marine grade aluminium and stainless steel switchboards comply with the corrosion test without actually being tested?

As per AS/nZS 10.2.2, the corrosion resistance test is only required for ferrous material/parts.

The electrician becomes the assembly manufacturer and takes on that responsibility in the interpretation of AS/nZS 61439. They become responsible for the design. They can follow instructions from the original manufacturer or do their own thing, in which case they are responsible for providing design verification evidence to support a potential compliance claim.

Following the question on buying overthe-counter, for the everyday Joe doing small jobs, this could potentially be a major cost expense to the end user/ customer. It will also take away from a simple solution for a fix to become a longer completion time on the job.

Only if the instructions are complex. It is expected simple instructions will be provided. The alternative is far more serious. Overloading a Distribution Board (DB) can start a fire, posing a risk to people on site.

Can a switchboard (MCC) be relocated with its corresponding equipment?

If the environmental conditions (e.g. ambient indoor/outdoor temperature) and installation conditions (e.g. prospective fault levels) at the new location are the same or better, this may be possible. However, a proper study would need to be done to confirm this.

If we make cut-outs in the switchboard doors/panels will this affect the arc fault containment ability. Is there a minimum size of cut-out which would be acceptable?

Cut-outs will affect the internal arc fault performance of the assembly. The term ‘containment’ is not used in AS/nZS 61439 and it should not be used in this context since arc events can be expelled from the board in safe directions.

Can you put an IP55 switchboard within an outer enclosure to raise the Ingress Protection (IP) rating? Or will that affect how the switchboard is designed?

The IP rating of a switchboard is not raised when fitted inside an outer shell. The outer shell has one IP and the inner enclosure has another. This will affect the switchboard’s performance based on airflow, temperature inside the enclosure etc.

View the full webinar

To find out more about AS/nZS 61439, including the key changes, definitions, documentation requirements and contractors’ responsibilities, view the full webinar: www.bit.ly/asnzs61439