It’s about time to update the Wiring Rules. Lucy Finlay looks at what has happened since 2018 and what might be changing in AS/NZS 3000.

The current edition of AS/NZS 3000, the Wiring Rules, was first published in 2018. In the intervening years, there have been three amendments and one ruling published.

At the same time, Australia has embarked on an energy transition that is changing the way we generate, store, transmit and use electricity. Federal and state policies continue to evolve at an ever-increasing rate, as do associated regulatory instruments such as the Integrated System Plan published by the Australian Energy Market Operator (AEMO) and National Construction Code (NCC).

It’s time for a new edition of AS/NZS 3000 that will meet these new challenges whilst also continually improving the standard for all readers.

Standards Australia technical committee EL-001 is responsible for the maintenance of AS/NZS 3000. Earlier this year the committee began the journey of preparing for the next edition. Early on it was identified that three emerging areas needed specific attention: earthing, energy systems and electric vehicle charging.

One of the biggest changes relating to energy systems has been the publication of the latest edition of AS/NZS 4777.1 Grid connection of energy systems via inverters. The next edition of AS/NZS 3000 needs to ensure that the core tenants of both AS/NZS 3000 and AS/NZS 4777.1 are aligned.

In response to end user requirements and advancing technology, AS/NZS 4777.1 has introduced two new supply types, substitute supply and independent supply. The new edition, in particular section five has been organised based on supply types. Hopefully, this will make it easier for all readers to get straight to the relevant requirements for the job at hand.

Another key change in the latest edition of AS/NZS 4777.1 is the provision for the future of vehicle-to-grid (V2G) by including provisions for electrical vehicle (EV) supply equipment that can supply power to the electrical installation.

It’s recognised that AS/NZS 3000 must remain the lead standard for safety requirements of low-voltage electrical installations. In both scenarios described above, some requirements are unique to each scenario, yet there are also common requirements that must remain aligned with Part 1 and Part 2 requirements of AS/NZS 3000. A dedicated working group that brings experts from technical committees EL-001 and EL-042, responsible for AS/NZS 4777.1, together have been established to make recommendations that will ensure that this alignment occurs. It’s likely that Section 7.3 of the AS/NZS 3000 will undergo significant structural changes that will provide direction on all supply types including those within the scope of AS/NZS 4777.1.

While AS/NZS 4777.1 addresses the installation requirements of V2G EV chargers, there is a need for AS/NZS 3000 to provide installation requirements for unidirectional Mode 3 and Mode 4 EV chargers. AS/NZS 3000 Appendix P is currently informative which restricts the usefulness of the appendix to be a source of information only. Once again, a dedicated working group has been established to make recommendations on what needs to change in the next edition of AS/NZS 3000.

Assessing the maximum demand for EV chargers has been a challenging issue for the industry in recent years. This is exacerbated in installations with multiple EV chargers. The current guidance in Appendix P is that every single connecting point is considered to be used at its full rated current. Based on this guidance it doesn’t take too long before the required size of consumer mains and sub mains become unachievable. The 2025 edition of the NCC will likely need to provide interim guidance on the calculation of maximum demand for EV chargers until the next edition of AS/NZS 3000 is published.

Load management systems (LMS) have a role to play in addressing the challenge of maximum demand. An LMS manages the charging across multiple EV chargers. This can be done via static limits, dynamic limits and even time of use control. Some LMS can even look after phase balancing automatically when connected vehicles only use one phase.

However, the use of digitisation to achieve safety outcomes does raise an important consideration: How can we ensure that we create effective safety requirements that consider the role that digitisation will play in the increasing electrification of buildings? There is a lot of work occurring internationally, particularly at the International Electrotechnical Commission (IEC) at the intersection of digitisation and electrification. Many local standardisation committees, including EL-001 actively participate in some of this international work. As EL-001 progress their work in producing the next edition of AS/NZS 3000, many international learnings will be considered for inclusion.

Discussions are also occurring at an international and local level on the applicability of various earthing systems for EV charging. The MEN earthing system that we use in Australia and New Zealand is described in IEC 60364 (the international equivalent of AS/NZS 3000) as a TN-C-S system. The TN-C-S system is unique to Australia, New Zealand, the UK and Ireland. The TN-C-S system is a combination of TN-C and TN-S systems. Other standardised earthing systems are TT (earthed neutral) and IT (isolated neutral).

As an earlier adopter of EVs, the UK have already made some amendments to earthing requirements for EV charging in their Wiring Rules, BS 7671. There is still a lot of work to be completed to understand the relevance of these changes to the Australian and New Zealand electrical installations. Examples such as this one highlight the depth of technical investigation and debate that is occurring within EL-001 to ensure the next edition of AS/NZS 3000 will meet the challenges of the energy transition and the expectations of the electrical industry.

A key outcome of the work completed this year to date has been creating the right structures that enable EL-001 to bring some of the best technical minds to help address these challenges. We can expect that the pace of policy and regulatory instrument evolution will not slow down any time soon. The challenge for EL-001 will be to deliver the next edition of AS/NZS 3000 within a time frame that will enable the electrical industry to deliver on the bold policy ambitions.