What Are the Rules for High Voltage Electrical Installations on Sydney Commercial Sites?

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What are the rules for high voltage electrical installations on Sydney commercial sites? In Australia, high voltage electrical installations, generally anything exceeding standard low voltage supply, have to comply with AS 2067, the dedicated substations and high voltage standard, rather than the everyday AS/NZS 3000 wiring rules that cover most homes and businesses. This matters for larger Sydney commercial and industrial sites that take their own high voltage supply and step it down on site, since the design, clearance and protection requirements are a different scale of project entirely from a standard three phase upgrade.

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1. Why high voltage sits outside the everyday wiring rules

AS/NZS 3000 is written around low voltage installations, the voltages found in a standard home, shop or warehouse. Once a site's demand grows large enough to justify its own high voltage supply, typically to avoid the losses and limitations of stepping everything down through the network first, the electrical design moves into a different risk category entirely, with far higher fault currents and far less tolerance for error. AS 2067 exists specifically to set the design, clearance, earthing and protection requirements for this category of installation, covering substations and the high voltage equipment that feeds them.

2. Where AS/NZS 3000 still applies on a high voltage site

Even on a site with its own high voltage supply, AS/NZS 3000 has not disappeared entirely. The standard specifically notes that portions of an installation operating at low voltage, including the low voltage cables and switchgear associated with an on site high voltage transformer, still fall within its scope. In practice this means a large commercial site typically has two distinct zones of compliance, the high voltage side governed by AS 2067, and everything downstream of the site's own transformer governed by the familiar AS/NZS 3000 rules that also apply to a standard commercial switchboard.

3. Who actually needs their own high voltage supply

Most Sydney businesses never need to think about high voltage at all, a standard three phase upgrade comfortably covers the vast majority of commercial and light industrial demand. High voltage becomes relevant for sites with genuinely large, continuous loads, think major manufacturing plants, large data centres, hospitals, shopping centres and similar facilities where the economics and reliability of taking supply at high voltage and stepping it down on site outweigh staying on a standard low voltage connection. Our guide to three phase power for warehouses and industrial units is a useful comparison if you are trying to work out which category your site actually falls into.

4. The distributor approval process

Taking a new high voltage supply, or installing an on site substation to be fed from the network at high voltage, requires a formal application and approval process through the relevant network distributor, well beyond the standard connection application used for a low voltage upgrade. The distributor assesses network capacity, protection coordination and the proposed substation design before any construction can proceed, and this process typically runs in parallel with the site's own electrical design work rather than afterward. Since Sydney sits across both Ausgrid and Endeavour Energy territory with different technical requirements, it is worth confirming which network actually serves your site before engaging a high voltage design partner, and you can check your network area in seconds with our postcode checker. Our guide to network demand tariffs for Sydney businesses is a useful companion read, since large demand and high voltage supply decisions are often made together as part of the same broader cost and capacity planning exercise.

5. Design, competency and accreditation requirements

High voltage design and installation work demands specific competencies that sit well outside a standard electrical licence, and in most cases the work is carried out in direct coordination with the network distributor's own technical requirements rather than against AS/NZS 3000 alone. This is genuinely specialist territory, and a business considering a high voltage supply should expect their electrical contractor to either hold that specific accreditation or bring in a specialist high voltage design partner, rather than treating it as an extension of standard commercial electrical work.

6. Why this often starts with a Level 3 design assessment

Before any high voltage decision is finalised, it is worth having a proper capacity and demand assessment carried out on the site, covering what the business genuinely needs now and over the medium term, and whether that need can still be met more simply through a low voltage upgrade. Our Level 3 design service covers exactly this kind of capacity planning for larger commercial sites, and our guide to Level 3 design for small commercial capacity upgrades explains how that assessment process typically works in practice, even for sites that end up staying on a standard low voltage connection.

7. Ongoing maintenance and compliance obligations

A high voltage installation does not become a set and forget asset once it is commissioned. Ongoing inspection, testing and maintenance obligations apply to high voltage switchgear and substation equipment, often set by the distributor's own technical requirements as a condition of the original connection approval, on top of whatever internal maintenance schedule the business runs. Facilities and operations managers responsible for a site with its own substation should treat this as a standing compliance obligation, not a one off project that ends at commissioning.

How High Demand Electrical helps

We are one of Sydney's most trusted Level 2 ASPs for commercial and industrial electrical work, and while high voltage design itself sits with specialist high voltage partners, we regularly help businesses work out whether they genuinely need to go down that path at all, or whether a properly planned low voltage upgrade meets their needs more simply and more affordably. If your site is weighing up a high voltage supply, our Level 3 design service is the right place to start, assessing your actual current and future demand before any bigger decision is made. For sites in Sydney's inner west considering a commercial upgrade, HD Inner West's guide to commercial three phase supply upgrades is a useful comparison for where the low voltage option tops out.

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