The Discussion


Questions and Answers from the webinar:

Q: What is the table number of the table specifier's guide in AS61439?
A: Table C.1 & C.2 of Annex C in SA SNZ TR 61439.0

Q: Is IEC 61439 applicable in US and Canada?
A: Thanks for the question. North America Switchboards are manufactured to UL and CSA standards. The main UL switchboard standards are UL 67, UL 508 A, UL 845 and UL 891. CSA Standards are largely aligned with UL Standards. The NHP CUBIC Modular Switchboard System has also been tested to these standards. Please see Page 4 of the or contact NHP for further information CUBIC 'Your Guarantee’ or contact NHP for further information.

Q: Does the switchboard design need to be tested by a 3rd party each time that an alternative brand of switch gear is used? This could get very expensive.
A: Table 13 of AS/NZS 61439.1 can be utilised to allow for substitution of components up to 3150A. Basically, the item to be used has to be equal or better in characteristics to a tested referenced design. Be aware that the variation notes in AS/NZS 61439.1 add criteria to meet other than just the 10 shown in the table. This may be difficult to achieve due the criteria that must be met and documented.
Note: The IEC standard does not allow substitution between brands as the AS/NZS version does.

Q: What is required with the new rules building a custom aluminium board using NHP products and who is responsible for compliance.
A: As per the standard, the Assembly Manufacture (Switchboard builder) is responsible to compile the Design Verification for any switchboard regardless of what equipment is being used within the enclosure. The board will still need to adhere to all 13 points in Annex D1 in AS/NZS 61439.1

Q: Orange boards are for LV?
A: In some parts of Australia this is what people are accustomed to and can be a site-specific specification, however there is no mandated requirement for LV Switchboards to be orange.


Q: If I have got quoted Switchboard that is type tested according to AS3439 and site specs have reflected to be compliant against AS/NZS 61439 what extra documentation do I need to request from OEM.
A: As you are only at the quotation phase it would be advisable to ask the Assembly Manufacturer (Switchboard Builder) to supply complete verification to AS/NZS61349.1 Table D1.

Q: Does the Form of Segregation come into the Annex D specification list? Should it be added?
A: Form of Separation is an electrical characteristic of the switchboard design and does not form part of the design verification requirements to Annex D, however the materials that make up the form of separation are subject to verification. It should be noted that Form of Separation is a selectable characteristic within Annex C of AS/NZS61439.0 which is an agreement between specifier and assembly manufacturer. It should also be noted that AS/NZS 3000 makes reference to forms of separation requirements with regard to designs above 800A and mitigation of arcing faults. Should it be added? It should certainly be confirmed to be correct as part of the inspection of the switchboard.

Q: What are the impacts, if any, on MSB sizing based on the latest standard
A: Regarding the physical difference between Two Main Switchboards constructed to AS/NZS 3439 or AS/NZS 61439, fundamentally there shouldn't be any difference in the physical size between the switchboards correctly constructed to either standard. It should be noted that as a trend the Technology Specialists that assist switchboard builders in the design of compliant AS/NZS 61439 Switchboards see a general increase in the physical sizing of Main Switchboards. This trend is partly due to the requirement for Switchboards to be design verified. This ensures that factors such as, the Ingress Protection Rating, Derating of ACB's and MCCB's, Current ratings of Busbars, Forms of separation, along with the physical space and volume that components are accommodated in within a switchboard are all considered especially with regards to temperature rise requirements.

Q: Supply Authority CT section. Does this also need to be tested for smaller MSB such as 200amp & 400 amp.
A: It would need to have Design Verification for relevant characteristics of Annex D in AS/NZS61439.1, e.g. short circuit withstand strength, temperature rise, etc. Dependant on the criteria this may not require a test, it maybe possible to verify by "Comparison with a reference design" or "Assessment". The switchboard may be exempt from verification of Short Circuit withstand strength if the board meets the criteria in AS/NZS61439.1 Clause 10.11.2.

Q: How does the standard propose to verify temperature rise within the switchboard assembly, particularly where the switchboard has multiple compartments? More specifically, how does one verify the busbar temperature rise and individual compartment / enclosure temperature rise based on an external ambient temperature of say 35 degrees C?
A: Section 10.10 of AS/NZS 61439.1 states the methods for determining temperature rise within a switchboard. Temperature rise can be verified by either Testing, Comparison to a reference design, or calculation (limitations apply).

Q: What standard applies to outdoor Switchboards if this one does not apply?
A: There is no specific standard that covers the installation of a AS/NZS 61439 switchboards within outdoor enclosures. It is imperative that all the installation parameters are taken into consideration when designing the switchboard. These include but not limited to, the IP rating, emissivity factor, physical volume of the enclosure and the solar gain heating effect, ambient temperatures. It should be remembered that AS/NZS 61439 is based on agreement between the original equipment manufacturer, the component suppliers, the switchboard builders, and the end users/consultants. The Switchboard needs to be suitably de-rated to ensure that temperature rise limits within the switchboard are not exceeded when installed in an outdoor enclosure.

Q: Please explain changes in 61439 with Arc Fault protection.
A: Annex ZC & ZD have been copied to AS/NZS61439.1 from AS/NZS3439, so nothing has changed from that perspective. However, AS/NZS3000:2018 now stated that either Annex ZD or IEC TR61641 can be utilised for Arc fault containment requirements.

Q: If a switchboard is under 250A but is not intended to be operated by an ordinary person (i.e. not domestic installation), does Part 3 comply or does it live under Part 1 for boards under 630A?
A: If the switchboard does not meet the criteria as determined by AS/NZS 61439.3, then it would need to be verified to AS/NZS 61439.2 requirements.

Q: If the board is rated at IP54 and above, does it still have to be compliant to AS61439?
A: Yes, no matter what IP rating the board is, it will still need to comply to AS/NZS 61439.

Q: If I were to specify testing for (a) power frequency withstand voltage, (b) impulse withstand voltage; etc what sort of cost am I imposing on the switchboard manufacture cost?
A: This would be determined by the assembly manufacturer, i.e. Do they have the equipment for in-house testing, or if an external test laboratory is utilised. Any specific testing requirements above those set out in AS/NZS 61439.1 would attract additional costs.


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