The new Australian and New Zealand Standard: Electrical Installations "Wiring Rules" (AS/NZS 3000:2018) supersedes all previous versions, including AS/NZS 3000:2007. It is a complete revision of the 2007 edition, with the goal of improving work methods and installation practices to meet the minimum regulatory requirements for a safe electrical installation. For electrical installers and design engineers across the country, updates now reflect new technologies, equipment, and improved installation practices.

The new wiring rules clarify the normative (mandatory) requirements as well as the informative (best practice) guidance standard, with the first section addressing new definitions to improve meaning such as 'Alteration,' 'Repair,' 'Alternative Supply,' 'Arc Fault Detection,' and 'Electrical Installation.' Changes to final sub-circuits (clause 2.6) will affect everyone in the industry, as it is now required for domestic, commercial, and industrial installations that final sub-circuits be protected by a 30mA RCD if you install a new final sub-circuit, make alterations or repairs to circuits or switchboards. There are, of course, exceptions where on RCDs adversely affect performance or disconnection by an RCD could cause a danger greater than earth leakage current, or when repairs are exclusively replaced with equivalent items in the same location.

Switchboard installation requirements (clause 2.10) now call for a 1.0 m minimum distance from all faces of a closed switchboard for non-domestic and unobstructed space of at least 0.6 m around switchboards with switchgear doors in any position or switchgear in a fully racked-out position. There is also expanded coverage for electrical switchboard installations with capacities greater than 800Amps, as well as an improvement in the protection requirements for Arc fault protective devices. As a result of too many brands in the industry failing to perform as their surge diverting claims, surge protection has also been updated to reflect modern arrangements of Surge Protective Devices (SPD).

Unfortunately, because these types of devices are sacrificial in operation and quantifying a lightning strike is nearly impossible, uneducated users are unaware of what constitutes inferior SPDs versus what the bare minimum of SPD protection is required. The wiring rules' Appendix F specifies the proper placement of SPDs to provide adequate protection. That is, for all main and sub switchboards, Metal Oxide Varistors (MOV) must be connected between the active phase and the neutral phase. In the absence of a MEN connection, a Gas Discharge Tube (GDT) between Neutral and Earth is used. It is worth noting that the use of spark gaps is not mentioned and is thought to be less effective due to the high let-through voltage. To coordinate proper protection, the use of circuit breakers and fuses to protect SPDs has been better outlined. The last thing a user wants is for the SPD to blow the main services fuse due to improper sizing.

For a well-protected environment, primary and secondary surge protection is essential, which can include diverters and filters. Further clarification is emphasized for the type of fail-safe alarm used in SPD operation, once again removing inferior SPDs from the market due to their unreliable and unpredictable thermal mechanical flag operation. SPDs with active fail-safe alarms use a properly energized relay to indicate AC power is active and provide the highest reliability due to the predictable indication of highly accurate thermal fuses. Thankfully, the AS1768 lightning protection standard answers these questions.