AS/NZS 61439 is in full effect and the switchboard and electrotechnology industry is fine-tuning their practices. Peter Vandenheuvel looks at what has gone well and what hasn’t.

With the adoption of the new switchboard Standard, there has been considerable difference of opinion on how often these occur.

There is a perception by some that switchboard failures are widespread whereas others are not that convinced, with considerable repercussions if we don’t get it right.

As part of this debate, the switchboard manufacturing industry has had doubts cast on its reputation which in itself is disappointing and could significantly affect how switchboards already in existence will be dealt with.

Moreover, it will be of much greater concern to every prudent existing switchboard owner and also to those companies they use when needing alterations involving existing switchboards, as well as switchboard builders who rely on previously done testing to past standards.

The main concern

The main concern is the interpretation of the Wiring Rules wording. If this requires the entire assembly to be upgraded and verified to the latest requirements, that – apart from being totally impractical – would place a huge and entirely unreasonable burden on the owner, the operator and the company doing the works.

Also, it will be breaking the fundamental precedent that – whenever a new edition of a standard is published – by virtue of having been placed in service prior, to have been deemed to comply with the requirements applicable at the time, so not to require any upgrading.

This is further supported by AS/NZS 61439 Part 1 ‘Preface’. That, paraphrased here, notes verification tests conducted to preceding standards as listed that fulfil its requirements need not be repeated.

Many failures?

That is extremely hard to pin down. There seems to be no openly accessible published data. Most surprising given the concern on switchboard failures.

A cursory desktop search for each of the jurisdictions for ‘electric safety shock incidents reports’ in each state and territory shows plenty of links drawing attention to the mandated requirement to report but no links to actual reports in the first two or three summary search pages.

Searches for statistics on the occurrence of switchboard failures in Australia also came up empty-handed.

So, using the adage ‘you can’t manage what you don’t measure’, it’s not unreasonable to assume this issue is not sufficiently high on the radar to require managing?

As there is no confirmed data for switchboard failures, the only thing we can do is look at overall electrical injury data.

Scarce data

An Electrical Regulatory Authorities Council (ERAC) ‘Electrical Fatal Incident Data’ report for the FY2020 – the latest year found – was somewhat more helpful. It listed eight deaths Australia wide but with six related to the distribution network. This only leaves two non-network-related incidents and as that also includes a Pandora’s Box of other causes, there is almost no chance it includes even one incident related to switchboards, let alone the failure of an actual switchboard.

A Flinders University study for the Australian Government entitled ‘Electrical injuries: hospitalisations and deaths’ covering FY2015 and 2016 – also the latest found – although difficult to analyse, gives some support to there being a lower than perceived occurrence. A total of 1,100 cases were hospitalised in the two years.

There were 112 attributed to electrical transmission lines, 58 to lightning, 803 in domestic situations and 39 due to other external causes. This leaves 146 ‘others’ of which it can be assumed 47% (or approx. 68) were persons working for ‘an income’. That would average out to 34 paid workers hospitalised spread across the whole of Australia each year for any reason whatsoever, which is again unlikely to be many, if any, switchboard failures.

As this report also included fatal electrical industries, it was noted that 55 deaths were found listed in the National Mortality Database. This included seven deaths while the person was working for an income.

Again, unlikely to be many, if any, due to switchboard failures.

This number of fatalities aligns with other anecdotal desktop researched information which suggests there are approx. 20 to 22 deaths from electrocution in Australia each year with more than half occurring in the home with appliances being a major cause. Hence, although none of the above is other than anecdotal, it at least confirms that there are likely to be very few serious switchboard related incidents.

A double-check

Double-checking from the only state-based ‘shock instance’ information found – the SA Regulator’s  ‘Regulation Roundup’ shock reports –  for the past three years, there were just four total shock incidents involving switchboards listed in three years, with the cause for all listed as ‘failures to properly isolate’.  So, all were human error with none caused by the switchboards themselves.

Even based on SA having only about 7% of the Australian population, it is still not unreasonable to assume that, like in SA, switchboards elsewhere are not as hazardous as some may think.

Now, some who perceive switchboard failures to be much more prevalent may believe there is an unwillingness to report these incidents. However, because all electrical shock incidents, regardless of their severity, must be reported in most states and territories, there would have to be a major failure in observance of the system for these to make any material difference.

Getting back to existing switchboards. Are these being unfairly judged? You be the judge. The only data reasonably available tends to suggest the contrary; they are both safe and performing satisfactorily.

Some praise for our industry

Having inspected a considerable number of switchboards first installed 30-to-50 years ago only recently, most of the properly designed, constructed and maintained were found in sound condition, all still fit for purpose. Also, there were very few devices replaced and those that had passed their ‘best before’ date.

My personal observation; looking at the low level of electrically-related unintentional accidental shock incidents and fatalities; every person in any way involved in our industry in any way, be it the regulators, engineers, inspectors, contractors, tradies, apprentices etc., should be very pleased for the excellent result of their efforts!

The early switchboards

For those still not convinced about the quality and reliability of most existing switchboards, it may be interesting to see how these came to perform that well, so it’s worth looking at how they developed.

When AS 3000, the wiring rules, was first published in 1923, switchboard technology was in its infancy with low fault currents and low circuit ratings. Most switchboards were ‘open panel’ with the equipment on the front and busbars and wiring at the back, ’built on the job’ and live at the front and the back.

The switching technology then was ‘knife’ switches and porcelain ‘rewireable’ fuses. And that changed little, apart from the switches getting spring assisted opening and being less reliant on operator skill and fuses upgraded to cartridge fuse elements in the 40s and 50s.

The main interconnections between devices were cables with clamps or soldered-on lugs, like for the remainder of the installation. So, electricians only needed the wiring rules for fabricating the typical switchboard of the day.

Safe access was a low priority

When the wiring rules was the only guide to their construction, there was little or no consideration for preventing accessibility to live parts; much like in the switchboards in some of the Frankenstein movies. In fact, access to these open panel switchboards in workshops, factories, high-rise hospital basements and the like was often only ‘regulated’ by a single tube horizontal handrail or a fence and gate.

But this all changed when our ‘homegrown’ switchboard industry started to gain momentum in the 1950s. Enclosed types fabricated in workshops certainly started becoming the norm in the late 1960s with open panel ‘Zelemite’ and ‘Ausbestos’ asbestos-based arrangements quickly falling out of fashion.

Hopefully, all these death traps are either now replaced or at least securely enclosed to prevent unauthorised access!

Switchboard standards history

As maximum demands and the resulting higher fault currents increased, they brought about the use of busbars and higher rated devices in the larger switchboards. This led to more guidance on switchboards in the wiring rules, including Appendix C ‘Current Carrying Capacity of Copper and Aluminium Busbars’.

It is worth noting here that prior to the inclusion of Appendix C, guidance for busbar design was generally based on the Copper Development Association of the UK (CDA) publication 22 entitled ‘Copper For Busbars’, first published in 1936 (still available today). It was and still is regarded as the go-to reference work, especially for busbar current carrying capacity and short-circuit withstand strength, which was then and remain, two of the most critical switchboard design issues.

Guidance on the key aspects of switchboard design has been in place since the late 1930s.

Prior to the publication of our own Standard, the fall-back position for professional manufacturers and users was British standard BS 4070.

Following that, the Australia-only Standard AS 1136 – published in 1974 – became the recognised standard.

It was then superseded by the joint Australian – New Zealand standard AS/NZS 3439 – Published in 1993 and based on IEC 60439.

Now, of course, the latest standard AS/NZS 61439 – based on the IEC standard IEC 61439 – was introduced through AS/NZS 3000:2018. This is for new assemblies now the only switchboard standard complying with the current wiring rules.

Many changes?

In the fundamentals? Not really. Why?  Because most of the underlying switchboard support data for designing for both temperature rise and fault withstand haven’t changed very much since the late 1930s.

It started with the CDA publication (then BS 4070), then since 1974 with AS 1136, since 1993 with AS/NZS 3439 and now AS/NZS 61439. And the fundamentals from the CDA publication have been carried through to the present day.

So, most of the important fundamental underlying principles have not changed. Even many of the other’s aspects have only been tweaked in a minor way.

And the little change is not surprising, after all, the underlying scientific principles they are based on were set in place at the time of the big bang 14 billion years ago and will continue to hold true for eternity; or at least until someone invents a room-temperature superconductor.

Therefore, for almost the last 50 years, switchboards built to the standards applicable at their time of manufacture have performed well – as confirmed by what appears to be the very low level of switchboard-related electrical incidents overall.

But even more importantly, surprise, surprise – with the absence of information to the contrary – it could be said that since the adoption of AS 1136 in the 1970s, switchboards of themselves were not the major cause of failure.

In fact, it could be argued they served the industry very well, as even some of those who previously considered switchboard failures more prevalent are now starting to agree

• There is little fundamental difference with the ‘1136’ and ‘3439’ switchboards already installed and these will continue to perform satisfactorily equal to ‘61439’.
• That only an extremely small proportion of the failures are caused by the switchboards of themselves.

Was AS/NZS 61439 the right way to go?

In my opinion, yes, albeit not for the reason of switchboard failures or that it is a quantum leap improvement (which it is not). However, in the bigger picture, because of technological advances, greater offshore market potential and worldwide harmonisation of standards, there was a need for a major revision of AS/NZS 3439.

And there were, in my opinion, compelling reasons for making the change, including;

• IEC moving to IEC 61439 made it sense for Australia to adopt the new standard.
• The fundamental requirements between 3439 and 61439 were similar.
• The resource within the Australian user base for revising 3439 was limited.
• Emphasis on compliance with 3439 was somewhat hit and miss
• Buyer emphasis on short circuit strength whilst overlooking temperature rise.
• It presented an opportunity to ‘reboot’ the compliance issues.

Do I think the move to AS/NZS 61439 has been a success? In part yes; it has made the playing field both in Australia and the IEC world a more level one. However, from a user-friendly perspective, I can only give it a ‘five out of ten’.

And don’t be lulled into thinking ‘613439’ is magically going to fix all your compliance problems and create a whole new ‘perfect world’, because it is now a world where the switchboard builders verify their own assemblies; the police policing the police.

Having said that, with all the background industry noise and obfuscation during the transition, the general lack of understanding and misunderstanding of the minimal differences between 3439 and 61439 (especially by some switchboard buyers), it has caused many switchboard builders to spend more money on repeating tests they had already done and didn’t need to pay for or do again.

Hopefully, all these costs will, one way or another, be recouped, from those who insisted on that excessive testing, if not already, then over time.

And remember; there is no single one-page certificate that will guarantee your purchases end-to-end. You, if the buyer or specifier, will need to still be very much on top of the standard in detail and be prepared to look at several documents or test reports before sign-off.

Also, as you, if the installer, will be the entity that signs off the entire installation, regardless of all the certifications you might be provided with. It is you they will come looking for to remedy the non-compliance and the responsibility if things go wrong.

Oh, and don’t bother to call for the ‘61439’ police; there are none.

Do, however, get advice from someone who can give you independent advice if you have an issue.