Wiring a Shed, Garage or Workshop: What AS/NZS 3000 Actually Requires

What does AS/NZS 3000 actually require when you wire a shed, garage or detached workshop? A detached structure is treated as its own building for electrical purposes, which means it needs a properly sized submain cable from the main switchboard, correct protection and earthing for that submain, and its own main or isolating switch so everything inside it can be shut off in one go. It is not simply a case of running a cable out the back and plugging in a power board.

⚡ Quick Answers: Wiring a Shed or Workshop

• Does a shed need its own main switch? Yes, any outbuilding with its own switchboard needs a main or isolating switch on that board under AS/NZS 3000.
• Does my shed need RCD protection? Yes, circuits supplying powerpoints and most lighting in an outbuilding need the same safety switch protection as the rest of the house.
• Does a shed need its own earth stake? It can be earthed either with a protective earth run alongside the submain from the house, or as its own separate MEN installation with its own electrode, depending on the setup.
• Can I just run an extension cord to my shed? No, a permanent extension cord is not a compliant or safe way to supply a shed with real power needs.
• Do I need council approval to wire a shed? Usually not for the electrical work itself, though the shed structure may need its own approval separately from the electrical connection.
• Is three phase power needed for a home workshop? Only if your equipment specifically requires it. See our guide on three phase power for a home workshop if you're deciding between the two.

1. A shed is its own electrical installation, not an extension of the house

Once a structure is separated from the main dwelling, AS/NZS 3000 treats it as an individual outbuilding with its own earthing and switching requirements, even though it's still fed from the same property. This matters because a lot of older or DIY shed setups were wired as if the shed were just another room, with no isolating switch and no clear earthing arrangement, which doesn't meet current requirements and can be a genuine safety issue during maintenance or in a fault.

2. Sizing and protecting the submain cable

The cable run from your main switchboard to the shed, called the submain, has to be sized for the actual load the shed will carry, not just whatever cable happens to be lying around. A shed used for basic lighting and a couple of powerpoints needs a much smaller submain than one running welding equipment, a table saw, or an air compressor. Voltage drop over the distance to the shed also has to be accounted for, which is why a longer run to a rear yard shed sometimes needs a larger cable than the same equipment would need closer to the house.

3. The main switch requirement

AS/NZS 3000 Clause 2.3.4.1 requires any shed, garage or outbuilding with its own switchboard to have a main or isolating switch fitted to that board, so the entire building's supply can be cut in one action. This is a basic safety requirement for anyone working on equipment or wiring inside the shed later, and it is one of the most commonly missed items on older or owner built shed power setups.

4. Earthing: two accepted methods

A shed can be earthed in one of two ways under AS/NZS 3000. The first is running a dedicated protective earth conductor alongside the submain back to the house's main earthing system, which is the simpler and more common approach for a typical backyard shed. The second is setting the shed up as its own separate MEN (multiple earthed neutral) installation, with its own earth electrode and no more than one MEN connection inside that outbuilding, which an electrician might choose for a larger workshop or where the submain run is long. Combined outbuildings sharing one submain must use the first method and cannot be set up as a separate MEN installation.

5. RCD protection and powerpoints

Powerpoints and lighting circuits inside a shed need the same safety switch, or RCD, protection required anywhere else in a modern installation. This matters in a workshop environment specifically because of the equipment typically used there, power tools, extension leads and often damp or dusty conditions, all of which raise the consequences of a fault if the circuit isn't properly protected.

6. What a compliant setup actually looks like on site

In practice, a properly wired workshop shed has a correctly sized and protected submain from the house, a small distribution board inside the shed with its own main switch, RCD protected circuits for powerpoints and lighting, and a clear, consistent earthing arrangement matched to the layout. If the shed is also going to run heavier equipment later, it's worth having that conversation with your electrician up front, since planning for a bigger submain now is far cheaper than redoing the run in a few years.

How High Demand Electrical helps

High Demand Electrical wires sheds, garages and home workshops properly across Sydney's West, South West and Sutherland Shire, sizing the submain for what you actually plan to run rather than the bare minimum, and getting the main switch and earthing arrangement right the first time. If your workshop equipment needs more than standard single phase power, we also handle the step up to three phase power where it's genuinely needed. Book a site assessment and we will scope the submain, switchboard and earthing together, rather than quoting blind.

Shed and Workshop Wiring FAQs (Sydney)

Does a shed need its own main switch?

Yes. AS/NZS 3000 Clause 2.3.4.1 requires any outbuilding with its own switchboard to have a main or isolating switch so the whole building's supply can be shut off in one go.

Does my shed need its own earth stake?

Not necessarily. It can be earthed with a protective earth run alongside the submain from the house, or set up as its own separate MEN installation with its own electrode, and your electrician will choose based on the distance and how the shed is used.

Can I run an extension cord to my shed instead of proper wiring?

No. A permanent extension cord is not a compliant installation and becomes a real fire and shock risk over time, especially if it's exposed to weather or gets run over by equipment. A proper submain and switchboard is the right fix. See our earthing and bonding basics guide for more on how this all fits together.

Do I need a Level 2 electrician for shed wiring?

Usually not, since a shed submain from your existing board is standard licensed work. A Level 2 ASP is only needed if the project also involves new network side work, like a private power pole.

If you're planning a shed, garage or workshop power upgrade, get a power supply upgrade quote from High Demand Electrical or call 0402 559 777. Every quote starts with a site assessment, since the right submain size depends entirely on what you're actually going to run out there.