Short answer: A granny flat usually gets power in one of two ways: a sub-main from the main house switchboard to a sub-board in the granny flat (one meter, one bill), or a separate connection and meter (separate bills). The sub-main option is internal work for a licensed electrician. Separating the supply into two metered connections involves the network, so it needs a Level 2 Accredited Service Provider and an application to Ausgrid. Blue Link is not Level 2 accredited.
Granny flats are a popular way to house family, add rental income or create a work studio, and Inner West blocks are often just big enough for one. The electrical side is easy to underestimate, especially the question of whether to have a separate meter. Here’s how it works.
This is general information about the electrical side. Planning approval for a secondary dwelling is a separate process, so check with your certifier or council.
Option 1: sub-main from the house
A cable (the sub-main) runs from the main switchboard in the house to a sub-board in the granny flat. Everything is on one meter.
Pros
- simpler and usually lower cost
- no network application needed in most cases
- one electricity account
Cons
- one bill for both dwellings, so you’ll need to share costs informally or with a sub-meter (check the rules if you’re renting it out)
- the house’s supply and main switchboard must handle both loads
Option 2: separate connection and meter
The supply is separated so the granny flat has its own connection point and meter, and its own retail account.
Pros
- separate bills, simpler for tenants
- a separate account with your retailer
Cons
- involves network-side work and an application to the distributor
- usually more expensive and takes longer
- there may be extra fees for a new connection point
The NSW Government’s guide to altering electricity supply explains that changes to your connection need an Accredited Service Provider and an application to your distributor, which is Ausgrid in the Inner West.
Where Level 2 fits in
| Task | Who does it |
|---|---|
| Sub-main cable, sub-board, wiring inside the granny flat | Licensed electrician (e.g. Blue Link) |
| Main switchboard upgrade (customer side) | Licensed electrician |
| Separating supply, new service line or connection point | Level 2 Accredited Service Provider |
| Installing a new meter | Arranged through your retailer and metering provider, with Level 2 work as needed |
| Supply upgrade, e.g. to three phase | Level 2 Accredited Service Provider and Ausgrid |
Blue Link is not Level 2 accredited. We do the wiring on your side of the meter and can work alongside a Level 2 provider if your project needs one. See what is a Level 2 electrician.
Check the load first
A granny flat adds a lot of load: a cooktop or oven, hot water, air conditioning, laundry and lights. Before deciding, your electrician should:
- Estimate the granny flat’s maximum demand based on its appliances
- Check the main house’s existing load and supply capacity
- Check the main switchboard for space and condition
- Plan the cable route from the house to the granny flat
If the combined load is too high for the existing supply, you may need a supply upgrade, which brings in Level 2 work anyway.
Electrify from the start
Many new granny flats are all-electric, which avoids running gas. Consider:
- an induction cooktop
- heat pump hot water
- efficient split system air conditioning on a dedicated circuit
- LED lighting throughout
- room for solar or a battery later; see getting your switchboard ready for solar
Smoke alarms and safety
A new granny flat must meet the building rules for smoke alarms, which for new homes generally means mains-powered, interconnected alarms. Safety switches are required on new circuits. See interconnected smoke alarms.
Plan the cable route early
Inner West blocks are tight. The cable from the house to the granny flat may need to run under paving, along a side passage or through the house. Plan it with your builder before landscaping. Similar issues come up in power to a shed or studio.
Building a granny flat? We do the internal wiring, sub-boards, switchboard upgrades and sub-main cabling, and tell you upfront if you also need a Level 2 provider. Call 0421 772 661 or see our residential electrical services.
We work on granny flats and backyard studios in Ashfield, Croydon Park, Hurlstone Park and Dulwich Hill.
Frequently asked questions
Does a granny flat need a separate electricity meter?
Not necessarily. Many are supplied by a sub-main from the main house on one meter. A separate meter gives separate bills but needs network work by a Level 2 Accredited Service Provider.
Who installs a separate meter for a granny flat?
Separating the supply and creating a new connection needs a Level 2 Accredited Service Provider and an application to Ausgrid, with the meter arranged through your retailer. Blue Link is not Level 2 accredited.
Can my electrician run power from the house to the granny flat?
Yes. A licensed electrician can install a sub-main from your main switchboard to a sub-board in the granny flat, if the supply and switchboard can handle the load.
Will a granny flat need a switchboard upgrade?
Often, especially in older homes with limited space or no safety switches. An electrician can check.