Technical Articles

GSES communicates factual, up-to-date and evidence-based information for publication. This includes information on the issues surrounding DC circuit breakers, earthing fundamentals, how to sell solar, and information on isolator enclosures.

AS/NZS 5033 amendment drafts out for comments: What are the changes?

The draft of amendments to AS/NZS 5033:2014 Installation and safety requirements for photovoltaic (PV) arrays was released for public comment in early February 2018. The comments period will close on 15th March 2018. The draft amendment 1:2018 and draft amendment 2:2018 are available for download free of charge from SAI Global.

Standards updates and amendments are a necessary hurdle for an industry that is constantly growing in size and experience, and that encounters an ever-broadening range of products. Amendments are introduced to standards to better reflect current PV system installation practices and applications.

The main changes which are of interest to PV system installers and designers would be the changes to DC isolators’ applicable utilisation category and sizing requirement, and installation methods pertaining to wiring systems in junction boxes, combiner boxes and isolator/disconnector boxes. Additional requirements on hardware such as inverters and isolator enclosures have also been introduced, which can affect selection of equipment for PV systems.

To assist the industry with understanding and providing feedback on the draft amendments, this article is produced to describe the key updates to the standard and what they mean for PV system designers and installers. Please note that not all changes are included here; GSES recommends that installers read the standard for themselves to ensure they are aware of all draft changes and have an opportunity to provide comments prior to publication.

Clarifying the definition of ‘disconnector’ (Amendment 1)

Most of the changes described by Amendment 1 is a result of a clarification in the definition of ‘disconnector’, including providing a distinction between disconnectors with and without load-break capacities and noting that a ‘switch-disconnector’ is a disconnector with load break capability. This results in many instances of ‘switch-disconnector’ being replaced with ‘disconnector’. The practical implication of this proposal is that in some instances circuit breakers may be used instead of switch disconnectors.

Figure 1 – Switch symbols. From left to right: disconnector, switch disconnector, and circuit breaker with isolation function

Sealing of cable exiting conduit or ducting (Amendment 1)

Amendment 1 specifies that cable entries and exits of isolator enclosures, whether through conduit or ducting, must be sealed. The amendment also specifies that silicone cannot be used as a primary means of sealing. This requirement has been part of the Clean Energy Council’s PV system install and supervise guideline and therefore would be a familiar requirement to most installers. See draft clause amendments.

Array disconnection from Inverter (Amendment 1)

The allowed methods of array disconnection from inverters has been clarified to ensure that, where applicable, there is separate screening of live parts to remove the risk of electrical hazard when removing or replacing the inverter. See draft clause amendments for more details.

Wiring installations in junction boxes and isolator enclosures (Amendment 1)

Draft amendment 1 specifies additional installation requirements at junction boxes and isolator enclosures with the aim of preventing water ingress into such enclosures. Many of the draft changes, such as bottom entry of conduits into enclosures and the use of cable glands to facilitate cable entry into conduits, have been part of the Clean Energy Council’s PV system install and supervise guideline and therefore would be a familiar requirement to most installers. The amendment also allows the use of purpose made valves to reduce likelihood of moisture build-up within enclosures as a result of condensation. See draft clause amendments for more details.

Changes to isolator selection, installation requirements, and electrical requirement (Amendment 2)

The draft amendment 2 introduces changes to isolator selection, such as an isolator enclosure’s IP rating and utilisation category, introduces installation requirement previously prescribed only in CEC guidelines, and specifies isolator voltage and current requirements based on the isolator’s overall rating as well as make and break rating.

Many of these changes refer to a new Australian Standard, AS 60947.3, which is currently still in the draft phase. This draft Australian Standard, which outlines the testing requirements and labelling requirements of DC isolators for use in Australia, is also available for public comment until March 15th, 2018. It is strongly encouraged that interested PV installers and designers provide comments to this draft Australian Standard to ensure that the regulations applicable to isolators best reflect the needs of the industry.

Isolator enclosure IP rating

Isolator enclosures for outdoor use will require an IP rating of IP56NW. IP56NW, where NW stands for ‘no water’, is a classification specified by draft AS 60947.3.

Utilisation category DC-PV2

DC isolators for use in PV systems will need to have the utilisation category DC-PV2 instead of DC-21B. DC-PV2 is a utilisation category which is specified by the draft AS 60947.3.

Introduction of temperature effect to isolator

Draft amendment 2 requires that the effect of temperature on an isolator’s rating be taken into account when selecting isolators. The amendment specifies the expected ambient temperature depending on if the isolator is located: indoors, outdoors in a fully shaded location, or outdoors exposed to sunlight. For isolators that are located indoors or outdoors in a fully shaded location, the specified ambient temperature applicable is 40 degrees Celsius. For isolators that are located outdoors and exposed to sunlight, which includes isolators installed in enclosures which are shaded fully by a metallic shroud but otherwise exposed to sunlight, the applicable ambient temperature is 60 degrees Celsius.

At the time of writing, it is unclear whether this requirement is in line with the Clean Energy Council’s installation guidelines, which instructs installers to de-rate DC isolator ratings to ambient temperature plus an additional 40 degrees, or if rooftop DC isolators require the specified additional derating to meet Clean Energy Council’s installation guidelines.

Isolator voltage and current requirement

Draft amendment 2 has introduced a major change in the isolator voltage and current requirement. For systems connected to a galvanically isolated (transformer) inverter, the requirement remains unchanged; the isolator’s voltage rating corresponding to the operational current as specified by Table 4.2 (1.25 x Isc in most cases) shall be equal to or greater than the PV array maximum voltage. However, for systems connected to a non-isolated (transformerless) inverter, in addition to the aforementioned requirements, the positive circuit and the negative circuit each have to be rated to the PV array maximum voltage for the make and break rated current, which is also specified by Table 4.2.

To summarise, this means that installers and designers will be referring to the isolator’s make and break current rating to determine the required “per-pole” current rating when connecting to a non-isolated inverter.

Figure 2. Isolator showing the positive circuit in red, and negative circuit in black. The positive circuit is circled. Where the isolator is connected to a non-isolated inverter, the isolator shall be rated to the PV array maximum voltage at the rated make and break current for each of the positive and negative circuit configuration.

Worked examples for selection of isolator

A new informative appendix, Appendix I, has been added as part of draft amendment 2 which steps through the process for selecting the correct isolator such that it meets temperature effect derating factors as well as the required current and voltage rating.

If you identify any content that is unclear, now is the time to let the standards committee know.

Transition period

There is no specified transition period for Amendment 1. That is, amendment 1 would be effective from the publication date. The specified transition period for amendment 2 is 12 months after publication date. The transition period is specified in the draft Preface of Amendment 2.

Have your voice heard

The draft amendment to AS/NZS5033:2014 aims to reflect the changing installation practices in the past 4 years and gives clarification to design and install requirements. The public comment period presents an opportunity to shape the future of the PV industry. To fully benefit from these amendments, industry members should review the documents and make comment in the coming weeks.

Submissions of comments to the draft standards must be made via the Standards Hub Website. The instructions and examples of comment submissions are available on this website.

Please ensure the instructions are followed in the submission of your comments.

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