AS4836:2011 has been superseded by AS4836:2023 and here's what you need to know....
AS/NZS 4836 was revised in 2023 and one of the big changes to the Standard was how it addresses arc flash. This article assumes a basic understanding of the term, Arc Flash. An introduction to arc flash will be the topic of a future article but for now, if you are unsure what arc flash is, a good place to start is here Arc Flash Tutorial (energycouncil.com.au).
Australia and New Zealand do not have their own standards dedicated to determination of arc flash risk and calculation of incident energies. However, by pulling together the pieces from a few standards as well as industry body publications, we can come pretty close to the complete picture.
So let’s start by taking a look at the main Australian and New Zealand Standards that point us in the right direction.
AS/NZS 3000 (The Wiring Rules) has a requirement that circuits greater than or equal to 800A consider arcing faults and protection against them. The Wiring Rules are a mandatory standard in that they are referred to within legislation.
AS/NZS 4836, whilst not a mandatory standard, provides some guidance around arc flash and selection of PPE. The previous version of AS/NZS 4836 was quite vague around the selection of PPE and fell well short of its international standard equivalents. The most recent release aimed to improve this and we’ll take a look at the outcome of that shortly.
ENA NENS 09 released by Energy Networks Association in 2006 and later updated in 2014 was intended to be a guideline for selection of PPE and calculation of incident energy. NENS 09 was somewhat ahead of its time in the way that it considered the propagation of the arc and this caused confusion with many unsure whether to apply recognised international standards or the Australian guideline.
From an international perspective, the main standards considered by this article include IEEE 1584, NFPA 70E and CSA Z462. The IEEE standard is widely accepted as the calculation methodology with the NFPA and CSA standards focussing more on risk assessment and application of suitable PPE. Note, the most recent version of the IEEE 1584 standard (2018) introduced configuration of the conductors into the calculation which brought the calculation more into alignment with NENS 09. Comparing calculation techniques could easily be a topic of its own so we will leave it at this for now and continue to the crux of this article which is to outline the changes in AS/NZS 4836.
Changes to AS/NZS 4836 can be characterized as either minor formatting and informational updates or functional changes. Key context to understanding this standard is knowing the target audience which is PCBUs and workers (generally electricians) exposed to working on or near live electrical equipment. Generally, larger corporations that have a whole suite of policies and procedures will have more onerous requirements or will have specifically tailored their procedures to their organisation and so the guidance presented in the standard will not apply. The standard is intended to act as a supplement where a particular policy doesn’t exist. For example, if a company does not have their own arc flash policy, they should opt to either follow the guidance presented in the standard or develop their own policy.
The informational changes from 2023 include:
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Arc flash related definitions in Section 1.4 (previously 1.4) updated to align with other published standards.
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Risk assessment. Section 2.3 talks about identifying risks. 2.3.4 (previously 2.3.3) aims to help the reader identify when there may be an arc flash related hazard. A key new point made in this section is the requirement for PCBUs to conduct an arc flash study where they are in control of equipment with a rated capacity of 800A or greater. What could this mean for you?
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Batteries. With batteries becoming more and more prevalent in industry, the standard has expanded on the section relating to batteries and d.c. supplies in 4.3.7 (previously 3.9.4). The standard doesn’t intend to provide prescriptive direction on battery design but it does provide very high-level guidance for readers on how to control risk and highlights d.c. arc flash as a hazard associated with them.
The functional changes include:
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Personal Protective Equipment (PPE), Section 12 (formerly 9).
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Previously, the standard was directed at “electrical workers” only. This language has been removed as it is well known that not only electrical workers are required to work near live electrical equipment.
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A key statement is made that reaffirms that this standard is only presenting guidance in the absence of something better. The example provided is that if an arc fault study has been carried out, this will likely supersede any PPE guidance provided in the standard.
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Table 11.1 (formerly 9.1):
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Language updated to align with other standards – “arc rated” versus “flame retardant”
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Table 11.2 (formerly 9.2) is where some significant change has taken place.
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The old table confused many for a number of reasons. Current ranges in the columns did not appear to have any basis, many of the PPE items were listed as “if required” by risk assessment leaving readers with little guidance on when these should be applied. Furthermore, the 3 columns with different current ranges effectively all contained the same information.
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The new table aims to simplify the PPE selection process for the reader.
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Current ranges are selected in an attempt to align with standard circuit breaker sizes but also to try and draw a line in the sand between domestic and industrial installations. In general, domestic installations will be rated to less than or equal to 63A and these types of installations typically would not require arc rated PPE.
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Colour coding of the table now aligns to the level of severity of the arc flash and hence, the required arc rating of the PPE. E.g. green suggests no specific arc flash PPE, yellow suggests low level of arc rated PPE, orange would indicate a medium level of arc rated PPE is required and red indicates the highest levels of arc rated PPE are required (often referred to as a “bomb suit” in the industry).
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Whist PPE is not shown in “categories”, an effort has been made to align with the category system that readers may be familiar with from international standards such as NFPA 70E.
Category 1: up to 4 cal/cm2
Category 2: up to 8 cal/cm2
Category 3: up to 25 cal/cm2 - this has been omitted from the table as many industries prefer to own just one bomb suit and have it rated to cover both Category 3 and 4
Category 4: up to 40 cal/cm2
Category 5: up to 75 cal/cm2 – this additional category was introduced to align with the Canadian CSA Z462 standard
Note: previously, it was considered that an incident energy beyond 40 cal/cm2 would have an associated blast that is to significant too protect against with PPE however there is increasing evidence to suggest that even though the energy level increases, the blast force can remain low enough that adequately rated PPE can still provide protection.
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Appendix B. This appendix previously contained information about electrical incident case studies. In the latest revision, this content has been replaced by additional supporting arc flash information in the form of guidelines. Much of the content is reproduced from the energy council guidelines (linked at the start of this article).
The appendix also contains some example arc flash labelling which readers may adopt in the absence of their own labelling scheme.
The final piece of information presented in the appendix is a lookup table (similar to those used in NFPA 70E and CSA Z462) which readers can apply in the absence of an arc flash study. It should be noted that if the table is used for determination of PPE and arc flash boundaries, the result will typically be more onerous than if a specific arc flash study is performed.
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