New Service Connection for a Sydney Granny Flat: Step by Step

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How do you get power connected to a granny flat in Sydney? In most cases the granny flat is supplied from the main house's electrical installation through new submains, not through a separate connection to the street. Whether that works for your block comes down to two things: whether the existing supply has the capacity to carry a second dwelling, and how you want the granny flat metered and billed. The step by step below covers both paths.

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1. Decide how the granny flat will be supplied

There are three broad arrangements. The simplest runs submains from the main house switchboard to a small distribution board in the flat, with usage folded into the main bill. The second keeps the same physical supply but adds separate metering, so a tenant can be billed in their own name. The third, a completely separate service connection, is rare for a secondary dwelling and generally only comes up on large or unusual blocks.

The right choice depends on how you will use the flat. Family use suits shared billing. A rental usually justifies separate metering from day one, because retrofitting it later costs more than doing it during the build.

2. Check the existing supply can carry the load

A granny flat adds a kitchen, hot water, air conditioning and sometimes a laundry to a supply that was sized for one dwelling. Before anything is built, your electrician runs a maximum demand assessment under AS/NZS 3000 that adds the flat's load to the existing house. We explain how that calculation catches people out in our guide to the balancing of load rule and switchboard inspections.

If the numbers do not fit, the fix is a power supply upgrade, and on many older homes that becomes the moment to consider a single phase to three phase upgrade so the property is not boxed in again by the next addition, like an EV charger.

3. Lodge the paperwork before committing money

The Service and Installation Rules of NSW require a written Application for Connection in specific situations, including larger loads and new or redeveloped multi residential installations, and the maximum demand calculation forms part of that application. Lodging late is one of the most common causes of connection delays, and the Rules specifically warn against spending money on designs or materials before the distributor has approved the application and set its terms.

Which distributor you deal with depends on where you live, so check your network area in seconds with our postcode checker before you start. Any work on the service itself is notified to the network through the standard service work paperwork your Level 2 electrician handles.

4. The physical connection work

Once approvals are in place, the work splits in two. Your electrician fits the flat's distribution board, circuits and safety switches. The supply side, which may include new consumer mains, an upgraded overhead service or underground service, a switchboard upgrade to make room for new metering and protection, and the metering position itself, is Level 2 work. If separate billing is part of the plan, a smart meter is installed against the new metering position by your retailer's metering provider.

5. Testing, inspection and switch on

Before the granny flat goes live, the installation is tested for polarity, insulation and earthing, and the supply work is inspected. What inspectors look at is covered in our post on what happens at a Level 2 site inspection. Only once everything passes is the installation energised and handed over.

Why it's Level 2 ASP work

Everything between the street and your meter sits on the network side of the line that ordinary electrical licences stop at. Consumer mains, service lines and metering can only be installed or altered by a Level 2 accredited service provider authorised by your distributor. Before you book anyone, it is worth reading how to verify a Level 2 ASP's accreditation.

How High Demand Electrical helps

High Demand Electrical handles the supply side of granny flat projects end to end: the maximum demand assessment, the distributor application, upgraded consumer mains and service lines, switchboard and metering work, and the final testing and energising. Because we are Level 2 accredited in both Ausgrid and Endeavour Energy areas, one crew covers the whole scope instead of you coordinating two contractors around one trench.

Granny Flat Connection FAQs (Sydney)

Does a granny flat automatically need a switchboard upgrade?

Not automatically, but often. If the main board is asbestos backed, has no spare ways or lacks modern protection, the submains for the flat cannot land on it as is. See our switchboard upgrade service for what is involved.

Can I run the granny flat off an extension lead or a single circuit?

No. A habitable dwelling needs its own properly designed circuits and distribution board. A single circuit will not carry a kitchen and hot water, and it would not pass inspection.

How long does the whole process take?

Wiring the flat happens with the build. The supply side depends on your distributor's approval and whether the network needs augmentation, which is why the application should be lodged early, not after the slab is down.

Do I need three phase for a granny flat?

Usually single phase capacity is enough if the existing supply is healthy, but ducted air conditioning or an EV charger can tip the numbers. The maximum demand assessment gives the real answer before you commit.

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Planning a granny flat and not sure your supply will cope? Get a power supply upgrade quote or call 0402 559 777. Every job starts with a site assessment so scope and pricing are confirmed before any work begins.