Ganged devices mean multiple inverter energy system supplies that are isolated together by a single switching mechanism. The supplies may be mechanically or electrically arranged such that a single action can isolate them all simultaneously instead of each inverter having completely separate and independently operated main switches.

The 2024 edition acknowledges that such philosophy has shifted, whereby modern systems operate as unified energy generation groups rather than duplicating hardware for each inverter; hence, for isolation purposes, such effectively interconnected inverter supplies may be treated as a single device.

This change does not relieve any of the safety obligations; it only helps define how several inverters shall be isolated in such a way that confusion is reduced and the clarity of the system improves.

Why the Standard Introduced This Change

The Australian market has witnessed rapid growth rates for distributed energy resources. For residential dwellings, solar, storage, or smart energy management systems are becoming commonplace. Commercial sites use multiple devices running in parallel to achieve higher capacities, ensuring redundancy.

Based on the previous interpretation, this will result in switchboards being filled with multiple inverter main switches, with each inverter having its separate switch. It is not clear what operating switches in an emergency situation would be required to sectionalize off all of the generation.

This issue is addressed in AS/NZS 4777.1:2024 through the incorporation of consolidation. Where inverters are fed together and are arranged to operate in isolation, it simplifies the understanding of the systems, making them easier to operate and safer under emergency situations.

Main Switch for Inverter Supply – A More Structured Approach

One of the most significant impacts of the ganged device clarification is on the main switch for supply to inverters. The 2024 edition imposes some common sense restrictions on how supply to inverters is arranged on a switchboard also supplying normal loads such as lighting and socket outlets.

Instead of allowing multiple independent inverter main switches to be dispersed on a board, the standard recommends that structured grouping be used. In cases where multiple inverters are used, designers are encouraged to use these multiple inverters in a coordinated isolation arrangement.

If two inverters are installed, their supplies can be ganged to switch together. This means they can be thought of as one supply for switching purposes. This improves the clarity of switchboards quite fundamentally, eliminating any unnecessary duplication of devices.

The main point is simultaneous isolation. If the operation of one switch is effective in disconnecting all the connected inverter energy systems, then it meets the intent of the standard.

Managing Multiple Inverters on One Switchboard

The 2024 version also adds constraints based on the number of inverter main switch components that are permitted on the switchboard during installation for other loads. This is important in domestic installations since we are adding multiple forms of energy.

Therefore, if the quantities of inverter supplies are rising beyond what is deemed satisfactory for the general switchboard, the configuration needs to be rethinked. At such a point, the idea of aggregation comes into play.

Instead of continuing to use separate inverter main switches, it is recommended that inverters be provided in a separate package with a single controlled output fed into a main switch. This maintains a clear and well-structured isolation.

Ganged devices are what make it possible by having several outputs of their inverters treated as one unit.

The Role of Aggregation Boards

For more complex installations, especially commercial systems, aggregation boards are increasingly relevant. These are enclosures containing multiple inverter outputs under coordinated switching and protection before feeding into a single supply into the main switchboard.

This is a perfect setup with regard to the philosophy of ganged devices. Instead of providing multiple independent inverter supplies to a main board, these are organized upstream and provided as a controlled, structured generation source.

The benefit is not just one of compliance. It improves maintainability, it makes fault finding easy, and it ensures that emergency isolation is straightforward. In commercial sites where there is high inverter capacity, this structured approach is far cleaner than attempting to manage a multitude of inverter switches within a general distribution board.

The Three Metre Visibility Rule

Another key clarification provided in the latest edition of AS/NZS 4777.1:2024 is regarding local AC isolation at the inverter. The revised edition has made specific changes to the addition of required AC isolators if the switchboard is placed near the inverter.

However, if the inverter is within three meters of the switchboard and can be seen from there, it might not be necessary for there to be an AC isolator at the inverter. This change recognizes that it is not necessarily beneficial for safety if there are redundant switching devices but the original one can be easily accessed.

If multiple inverters are ganged and isolated together at a nearby switchboard, this may simplify the installation. The visibility and access must, however, be real, and the switch must be easily identifiable and accessible without obstruction.

This is not the same as the removal of isolators. This is a simplification based on proximity and line of sight.

Emergency Isolation and First Responder Clarity

One of the strongest driving forces for the ganged device update is emergency clarity. An emergency situation, such as a fire or electrical shock, demands a clear ability to isolate generation.

When there are multiple inverter main switches without clear coordination, it can be a source of risk if all the generation sources are not disconnected. However, by allowing the inverter supplies to be ganged together as one source for disconnection, the risk is minimized as per the standard.

A clearly designated main switch for inverter supply which disconnects all inverter energy systems can be beneficial. This is true, especially in residential areas where individuals, including emergency response teams, may not necessarily be technically equipped.

A clear isolation hierarchy is a safety feature on its own.

Phase Balance and System Performance

Although ganged devices mainly affect the isolation characteristic, designers must ensure compliance with the phase balance requirement and DNSP export limits. Consolidating the inverter supplies will not eliminate the requirement to properly manage the distribution of loads.

In the case of a three-phase system, particularly one with multiple single-phase inverters, the allocation of the phases should still be taken into consideration. Consolidating the isolation should be the complement to good electrical design.

Grouping the inverter supplies often clarifies the phase management in a better way since it treats the system of generation as an entire entity rather than discrete components.

Labelling and Documentation

When using ganged devices, proper labeling is even more important. For main switches controlling inverter supply, it is critical that they are labelled as isolating multiple inverter energy systems.

Any application schedule, switchboard schedule, and single-line diagrams or ratings must be properly coordinated to show the consolidated approach. It must be clearly indicated that there is only one isolating device controlling several inverters if the physical layout shows this to be the case.

Inspectors use drawings and labelling to ensure compliance. Any discrepancies that exist between the actual site and drawings can mean avoidable problems.

Proper documentation is included as part of compliance with AS/NZS 4777.1

Residential Installations in Practice

In any Australian home, it is becoming more and more common that a PV inverter and a battery inverter are installed. In the previous way of installation, each would have had a separate inverter main switch and a corresponding AC isolator arrangement.

According to the 2024 edition, if properly designed, these systems can often be combined so that a single inverter main switch provides isolation for both systems. If the switchboard is within three metres of these systems and is easily visible, isolation on each of the AC systems is not necessarily required.

This leaves us with a cleaner board, less hardware, and a better shut down. It also makes future upgrades easier since the structure of the isolator is already in place.

However, it is important for the installers to ensure that the mechanism does, in fact, disconnect all the connected inverter energy systems simultaneously. This is a deliberate design.

Commercial Installations and Larger Systems

The effect of ganged devices is even more significant for commercial installations. Systems with many parallel inverters, large batteries, and sophisticated export controls have a high degree of benefit from such organization.

Instead of connecting multiple autonomous inverter main switches to a main switchboard, multiple supplies can be aggregated and coordinated to achieve a unified supply.

This improves clarity for facility managers and maintenance contractors. It also makes it easier to prove compliance with AS/NZS 4777.1:2024 for inspection purposes.

Large systems require the discipline of design. The new edition promotes that approach.

Aligning with DNSP Requirements

While the standard provides the installation framework, local Distribution Network Service Provider requirements still apply. Export limits, protection requirements, and metering arrangements must all remain compliant.

Ganging inverter supplies does not override DNSP conditions. Instead, it should complement them by providing a structured and easily understood isolation arrangement.

Designers must ensure that protection settings, export controls, and connection agreements remain aligned with the consolidated switching configuration.