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Wiring Rules 2018, Chapter Four: removing the uncertainty from safety

“Legrand Technical Director and Australian Industries Group representative of the EL-001 committee responsible for the changes to AS/NZ3000 Wiring Rules, Dennis Galvin, discusses the most important changes to Chapter Four of the 2018 Edition that will come into effect in November 2018.”

Chapter Four of the AS/NZ3000 Wiring Rules details the selection and installation of electrical equipment to ensure safety. The 2018 Edition represents incremental changes, compared with the last update to the Wiring Rules published in 2007, and can be considered a case of evolution rather than revolution.

Interestingly, the style of the latest Edition harks back to the way the Wiring Rules used to be presented 30 years ago. At that time, the rules were very prescriptive, clearly stating what needed to be done—and how—with little scope for misinterpretation or confusion. However, in time the language has softened along the lines of requiring an installer to make ‘a safe installation’ or provide ‘adequate protection’ without clearly defining what constitutes a safe installation or adequate protection. In practice, this meant that electricians would believe that their own way of doing things was ‘safe’ and ‘adequate’, but in practice there was a huge difference in the possible interpretation of these terms based on individual experience.

The 2018 Wiring Rules have now reverted to more precise instructions, leaving less possibility for an incorrect interpretation and providing a more standardised approach across the industry. Most electricians will welcome this approach, as they will have a more certain understanding of exactly what is required to meet code with fewer grey areas to consider. It also means that when an electrician is working on an existing electrical infrastructure, he/she will have a great sense of surety that the original installer worked to the same understanding of the Rules.

Arguably, the potential drawback to the more prescriptive approach is less flexibility in non-standard situations, although the style of the new Rules strikes a good balance in my opinion between clarity of requirements to meet code, while still providing the necessary ‘wiggle room’ where necessary. For instance, the Rules allow an engineer to sign off on a proposed variation as complying with Code if this can be demonstrated to be equal in safety to the standard approach as described by the Wiring Rules.

Overseas outlets

Unlike many European nations, Australia and New Zealand have been blessed with a single plug-socket system throughout the countries’ respective histories. This has meant that appliances are typically sold in Australia and New Zealand with factory-fitted plugs. This is undoubtedly a safer approach than in the UK, for example, where the existence of legacy socket systems in older properties meant that until quite recently appliances were often sold without plugs, necessitating the consumer to fit their own.

However, one of the downsides to the ‘single socket’ scenario is that the Wiring Rules have made little provision to date for meeting the plug socket needs of international travellers. There has previously been a move to install universal sockets or multi-outlet sockets—with large enough apertures to accept virtually any kind of plug pins—for hotel, hospitality and travel industry applications, but these electrical accessories have been banned as they didn’t confirm to the Wiring Rules’ requirements for the pin aperture. Equally, it wasn’t hitherto possible to simply install foreign plug sockets into an Australian or New Zealand building, as these would fail to comply with AS/NZ3000 standards.

Finally, the issue has been resolved in the 2018 revision to the Wiring Rules, which allows the installation of UK, US, French and German outlets, provide they conform to the International Electrotechnical Commission (IEC) standard for apertures and as long as they can accept only one type of plug. This move is intended to allow hotels and airports to legally install socket outlets in guest or public areas and will finally provide a safe workable solution to a problem that has plagued the industry for many years.

The new Wiring Rules for 2018 also deliver much clearer guidelines for recessed luminaires. In Australia, recessed luminaires can only be installed if they meet the minimum CA90 rating, which specifies that the casing will not exceed 90 degrees Celsius. Interestingly, New Zealand permits CA135 rated luminaires—designed not to exceed 135 degrees C—which is a somewhat counter-intuitive decision given that many of these luminaires will be installed in wood-frame buildings and the pyrolytic ignition temperature for wood is just 105 degrees C.

Aside from this, the Chapter Four section on recessed luminaires is more comprehensive than ever before, providing more stringent requirements and easier-to-understand guidelines especially with regard to installation in proximity to insulation material. Given the number of fires caused by downlights in recent years, this guide provides a timely revision.

Isolation issues

The 2018 Wiring Rules also introduce significant rules that require isolation switches on gas appliances—including gas heaters—stipulating that they need to be double-pole. This addresses the hazard associated with single-pole connections where it is possible to generate a voltage between neutral and earth during switching, thereby providing the potential to ignite gas.

While this inclusion makes sense from a safety standpoint, EL-001 committee members are hoping to amend it to avoid the necessity for large industrial-type switches in people’s lounge rooms. One option is to provide a socket for the appliance to enable it to be unplugged in order to circumvent the need for an unwieldy switch. This isolating switch section in Chapter Four is a major amendment to the 2018 Wiring Rules, with the more stringent requirements arising in direct response to numerous reported incidents, especially involving gas fitters.

Overall, the revisions to Chapter Four of the Wiring Rules are well thought through and intelligently presented, providing incremental improvements to safety in a number of key areas, and delivering clearer guidance through easier-to-understand instructions.

For example, the designation of IP zones for the outside installation of electrical equipment is much clearer than before. The Rules now state that if a line is drawn down at an angle of 30 degrees from the eaves—or any similar balcony or overhang—then above the point that this line intersects the wall, IP33 equipment can be used, whereas below this level IP55-rated equipment is required.

The presentation of sensible recommendations, such as this, that provide increased levels of protection against known hazards, and which are stated clearly and concisely, will help promote best installation practices throughout the industry and serve to remove much of the uncertainty from safety.

Tags: AFDD, circuit, compliance, legrand, legrand australia, Legrand New Zealand, RCDs, regulation, safety, Wiring Rules