Granny Flat and Secondary Dwelling Electrical: What a Gold Coast Build Needs
Electrically, a granny flat is a second dwelling. It has its own switchboard, its own circuits and its own compliance obligations, and it hangs off a supply that was sized for one house.
Most of the variation between electrical quotes on these builds comes from one early decision: how the flat is supplied and metered. Get that settled first and the rest of the scope is predictable. This guide covers the three options, whether your existing supply can carry a second dwelling, what a new installation has to include, and what changes once a tenant moves in.
Three ways to power it
| Submain, no separate meter | Private sub-meter | Separately metered supply | |
|---|---|---|---|
| What it is | A submain from your existing board to a new board in the flat | The same submain, plus a metering device so usage can be measured | The flat has its own retailer meter and its own account |
| Who gets the bill | You. One account for both dwellings | You, then you pass on the occupant’s share | The occupant, direct from their own retailer |
| Network involvement | None beyond any supply upgrade | None beyond any supply upgrade | Yes. A connection application to Energex |
| Ongoing cost | One daily supply charge | One daily supply charge | A second account, with its own daily supply charge |
| Best for | Family, or where you’d absorb the power cost anyway | Long-term rental where you want usage-based charging | Rental where you want the tenant fully independent |
A submain, with or without a sub-meter, is the simpler arrangement and the one that needs the least from the network. A separately metered supply gives the tenant full independence and comes with a second set of fixed charges for as long as the account exists. Whether and how Energex will provide it on your lot is confirmed through the connection application, so ask before you design around it.
The solar catch. If the main house has solar, a flat on a submain sits behind the same meter and can generally use it. A flat on its own meter generally can’t, because it draws from its own supply. Confirm the detail with your retailer before you commit. This choice is expensive to reverse.
Can your existing supply actually carry it?
The switchboard
A second dwelling needs a submain protected at the main board, and that takes physical space and spare capacity. Boards with ceramic fuses, no safety switches or no spare ways generally need replacing before anything else proceeds. A switchboard inspection settles that question in one visit, and our switchboard upgrade cost guide explains what drives the price if it does need doing.
The service from the street
The consumer mains feeding your property were sized for one dwelling. Add a second kitchen, a second hot water system and more air conditioning, and the total can exceed what the service supports. Some homes also need to move from single phase to three phase to carry it, which we explain in three phase vs single phase power. If yours does, that’s a three-phase power upgrade arranged through Energex.
A supply upgrade goes through Energex, the network for the Gold Coast. The application can be lodged by you, or by your electrical contractor on your behalf. It’s not always required. When it is, it runs on the network’s timetable and not the builder’s, which makes it the one item worth starting early.
It’s a new installation, so current standards apply in full
On a renovation, the obligations attach to the circuits you touch. A secondary dwelling is new work throughout, so the whole new electrical installation is built to the current standard. In practice that means:
- Safety switches across the circuits, not only the power points. The Electrical Safety Office’s advice for every home is safety switches on all circuits, including lighting, air conditioning, stove and hot water. A new board is the easy place to do it properly. See RCDs versus RCBOs for the device choice.
- Hardwired, interconnected smoke alarms. The Queensland Fire Department states that the Building Regulation 2021 requires all new dwellings to have smoke alarms hardwired and interconnected in specific locations: each storey, each bedroom, and hallways that connect bedrooms to the rest of the dwelling. Our guide to compliant smoke alarm installation has the detail.
- Dedicated circuits for kitchen appliances, hot water and air conditioning. The kitchen electrical guide covers cooktop isolation and circuit sizing, and it applies to a granny flat kitchen in full.
- Earthing and bonding for a detached structure fed by a submain, which is a different arrangement from a room addition on the main house.
- Internal and external lighting, with corrosion-resistant fittings outside on beachside blocks.
- A certificate of testing and compliance on completion. Keep it permanently. You will be asked for it when you sell, insure or lease.
The moment you rent it, the obligations change
Queensland’s planning department confirms that an amendment took effect on 26 September 2022 that removed restrictions on who can live in secondary dwellings. A granny flat can now be rented to anyone, whether or not they are related to the people in the main house, in every council area in the state.
Once it’s tenanted it is a rental property, and rental obligations apply:
| Obligation | What applies |
|---|---|
| Smoke alarms | Photoelectric, interconnected, in every required position. The lessor must test and clean each alarm within 30 days before the start of a tenancy |
| Safety switches | Required on all power point circuits within 90 days of the tenancy start date, with a fine of up to $1,500 |
| Electricity charges | Written into the tenancy agreement, and no more than the billable amount |
| Records | Compliance certificates and test records, kept from day one |
The safety switch rule for rentals is a legal minimum that covers power point circuits. A newly built flat with safety switches on every circuit already exceeds it. The smoke alarm hardware will be in place from the build too, though the testing and cleaning duty comes around with each tenancy. Our guide to landlord electrical safety checks covers the ongoing side, and we handle smoke alarms and safety switch testing for owners who want it documented.
What to expect on southern Gold Coast blocks
- Older timber homes around Palm Beach, Burleigh Heads and Currumbin often have boards that need replacing before they can carry a submain at all. Our guide to electrical problems in older QLD homes covers what else tends to turn up.
- Slab homes in Elanora, Burleigh Waters and Reedy Creek generally have newer boards and tighter cable routes.
- Beachside blocks at Tugun and Bilinga see salt-accelerated corrosion at terminations, so a board’s condition is often worse than its age suggests. We explain why in why Gold Coast switchboards corrode faster.
- Underground submain runs need the correct depth, mechanical protection and cable rating for the conditions, and they are far easier to get right before the landscaping goes in.
Getting the sequencing right
- Assess the main switchboard and incoming supply before the build contract is finalised, so any upgrade is a known item and not a variation.
- Decide the metering approach early. It changes the scope, the cost and whether a network application is needed.
- Confirm the planning and approval pathway with your certifier or designer.
- Rough-in once the frame is up and before the linings go on.
- Fit off after cabinetry and finishes, then test, certify and hand over the compliance paperwork.
The first two are where money is saved or lost.
Frequently asked questions
Does a granny flat need its own electricity meter?
Not necessarily. A submain from the main house with no separate meter is the simplest arrangement. A private sub-meter lets you measure the flat’s usage without involving the network. A separately metered supply gives the occupant their own retailer account, needs a connection application to Energex, and carries its own daily supply charge.
Will my switchboard handle a granny flat?
It depends on the board’s condition and spare capacity. A second dwelling needs a protected submain from the main board. Boards with ceramic fuses, no safety switches or no spare ways generally need replacing first. Have it assessed before you sign the build contract, so an upgrade is priced in from the start.
Can the granny flat use my solar?
On a submain, generally yes, because the flat sits behind the same meter as the main house. On a separately metered supply, generally no, because the flat draws from its own supply and its own account. Confirm the detail with your electricity retailer before you choose, as the metering decision is expensive to reverse.
Can I rent out a granny flat in Queensland?
Yes. A Planning Regulation amendment that took effect on 26 September 2022 removed the restrictions on who can live in a secondary dwelling, so it can be rented to anyone. A new secondary dwelling still needs building approval, and renting out an existing one may trigger a building application. Speak to a building certifier and your council first.
What electrical obligations apply once it’s tenanted?
The same as any Queensland rental. The lessor must test and clean each smoke alarm within 30 days before the start of a tenancy, and safety switches are required on all power point circuits within 90 days of the tenancy start date. A newly built flat will have the hardware. The testing duty is ongoing.
Do I need a separate supply upgrade from the street?
Sometimes. The mains feeding your property were sized for one dwelling, and a second can push demand past what the service supports. An upgrade means an application to Energex, lodged by you or by your electrician on your behalf. It runs on the network’s timetable, so find out before the build contract is signed.
At planning stage? Call us, or request a free quote. Knowing the board and supply position early is what keeps the electrical off your variations list.