Dennis Galvin reviews changes to Chapter 4 of the Standard that are designed to improve safety and clarify interpretation.

The style of the latest edition harks back to the way the Wiring Rules were 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 either. Electricians believed that their way of doing things was ‘safe’ and ‘adequate’, but in practice there was a huge range of possible interpretations based on individual experience.

The 2018 Wiring Rules have reverted to more precise instructions, leaving less potential 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 what is required for compliance with fewer grey areas to consider. It will also mean that when electricians are working on existing electrical circuitry in future they will have a great sense of surety that the original installer worked to the same understanding of the Wiring Rules.

A potential drawback of the more prescriptive approach is reduced flexibility in non-standard situations. However, the style of the new Wiring Rules strikes a good balance between the clarity of requirements for meeting the code and some ‘wriggle room’ where necessary.

For instance, an engineer can sign off a proposed variation as complying if this can be demonstrated to be equal in safety to the approach described by the Standard.

Overseas outlets

Unlike many European nations, Australia and New Zealand have been blessed with a single plug-socket system throughout the countries’ histories.

Appliances are typically sold in Australia and New Zealand with factory-fitted plugs – a safer approach than in the UK, for example. The existence of legacy socket systems in older British properties meant that until quite recently appliances were often sold without plugs, and consumers fitted 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 had 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 such accessories were banned because they didn’t conform to Wiring Rules requirements for the pin aperture.

Equally, it wasn’t hitherto possible to install foreign plug sockets in an Australian or New Zealand building, as these would fail to comply with AS/NZ3000 Standards.

Finally, the issue is resolved in the 2018 edition of 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 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. It will provide a safe, workable solution to a problem that has plagued the industry for many years.

The new Wiring Rules also offer much clearer guidelines for recessed luminaires.

In Australia, recessed luminaires can be installed only if they meet the minimum CA90 rating, which specifies that the casing will not exceed 90°C.

Interestingly, New Zealand permits CA135 rated luminaires, designed to not exceed 135°C. It 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°C.

Apart from this, the Chapter 4 section on recessed luminaires is more comprehensive than before. It contains more stringent requirements and more easily understood guidelines, especially with regard to installation near insulation material. Given the number of fires caused by downlights in recent years, this guide is a timely revision.

Isolation issues

The 2018 edition also introduces rules that require isolation switches on gas appliances – including gas heaters – stipulating that they 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 creating the potential to ignite gas.

Although this inclusion makes sense from a safety standpoint, EL-001 committee members hope 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, allowing it to be unplugged to obviate the need for an unwieldy switch. This isolating switch section in Chapter 4 is a major amendment to the Wiring Rules, its more stringent requirements arising in direct response to numerous reported incidents, especially those involving gas fitters.

Overall, the revisions to Chapter 4 are well thought through and intelligently presented, providing incremental improvements to safety in several key areas, and clearer guidance.

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

Sensible recommendations such as this will help promote best-practice installation throughout the industry and remove much of the uncertainty from safety concerns.

Legrand technical director Dennis Galvin is an Australian Industries Group representative of the EL-001 committee responsible for changes to the Standards covering installation requirements.