Most houses in Sydney need between 8 and 20 circuits. A small apartment with gas cooking can run safely on five or six, while a four-bedroom all-electric home with ducted air conditioning, an induction cooktop and an EV charger often needs 20 or more. The appliances you run decide the number far more than floor area does.
The Wiring Rules contain no line saying a house must have twelve circuits. They set how circuits are protected and grouped, and what the big appliances need, and the count follows from that. Here is how those pieces add up in a typical home, and how to tell when yours has run short.
What counts as a circuit?
A circuit is one cable run from a breaker at your switchboard out to the lights, power points or appliance it supplies. Each breaker or RCBO on the board protects one circuit, so counting them is the quickest way to count your circuits. The main switch, and any safety switch sitting above a row of breakers, are not circuits in their own right.
Shared circuits feed a group of lights or power points across a room or a floor. Dedicated circuits feed one large appliance and nothing else, which we explain in what is a dedicated circuit. Most homes have a mix of both.
How many circuits does a typical house have?
A three or four-bedroom house usually has between 10 and 16 circuits, made up of lighting, general power and a handful of dedicated appliance circuits. The table shows how that number builds up. Treat the figures as typical ranges rather than a requirement, because no two homes are laid out the same way.
| Circuit type | What it usually covers | Typical count, 3 to 4 bedroom house |
|---|---|---|
| Lighting | Ceiling lights, downlights and fans, split by floor or wing | 2 to 4 |
| General power | Power points in bedrooms, living areas, the laundry and outdoors | 3 to 6 |
| Kitchen power | Benchtop power points for the kettle, toaster and microwave | 1 to 2 |
| Oven and cooktop | Hard-wired cooking appliances, often one circuit each | 1 to 2 |
| Hot water | Electric storage or heat pump systems, often on controlled load | 0 to 1 |
| Air conditioning | Ducted systems and larger split systems | 1 per system |
| Extras | EV charger, pool or spa pump, a sub-board to a granny flat or garage | 1 each |
The spread is wide once you add it up. A gas-cooking home with no air conditioning sits near the bottom of the range. An all-electric home with two split systems, ducted air upstairs and an EV in the garage ends up at the top or past it.
What do the Wiring Rules actually require?
AS/NZS 3000 does not set a minimum number of circuits, but the way it controls protection and grouping pushes the count up. Three rules matter most in a home.
- Safety switch protection. New circuits in a home need 30 milliamp RCD protection, either from a shared RCD or from an RCBO on each circuit.
- No more than three circuits per RCD. A house with more than one circuit needs at least two safety switches, and a single RCD can protect three circuits at most. Our RCBO vs RCD guide covers how that plays out on older boards.
- Circuits sized to the load. Large fixed appliances get a circuit rated for what they draw, so an oven, cooktop, ducted air conditioner or EV charger nearly always ends up on its own.
Good practice adds a fourth. Electricians split lighting across at least two circuits on different safety switches, so one fault never leaves the whole house dark, which matters most on a staircase at night.
How many power points can go on one circuit?
There is no fixed cap on the number of power points per circuit in a house. Circuits are sized on expected load rather than outlet count, so an electrician might put two bedrooms on one circuit and give the kitchen benchtop a circuit of its own. What counts is how much runs at the same time. A bedroom of phone chargers and lamps draws very little, while a kitchen running the kettle, toaster and air fryer at breakfast draws a lot.
That is also why adding a power point to an existing circuit is usually straightforward, and adding a large appliance to one usually is not.
Not sure your board has enough circuits?
DM Electrical can count your circuits, check how your safety switches are grouped and tell you what your switchboard has room for. Based in Brookvale, Level 1 and Level 2 ASP accredited, available 24/7 across the Northern Beaches and wider Sydney.
What are the signs a house does not have enough circuits?
The clearest sign is a breaker that trips when two or three ordinary appliances run together. The breaker is working as designed in that case, because the circuit is being asked to carry more than it was built for. A few other signs tend to show up alongside it.
- Power boards everywhere. Double adaptors behind the TV, the desk and the bench usually mean the house was wired for far fewer appliances than it now runs.
- One trip takes out half the house. If a fault in the kitchen also kills the bedrooms and the lights, too many circuits share one safety switch, or the house has very few circuits to begin with.
- Only four or five breakers on the board. Open the board in a 1960s or 1970s Sydney house and it is common to find a lighting circuit or two, a power circuit or two, the stove and the hot water. That suited the appliances of the day.
- No spare positions. A full board means any new appliance circuit turns into a switchboard job.
A breaker that trips with nothing running is a different problem. That points to a fault somewhere on the circuit, and adding circuits will not fix it.
Can you add more circuits to an existing switchboard?
Usually, as long as the board has spare positions and your supply can carry the extra load. Each new circuit needs a free slot for its breaker or RCBO, a cable route from the board to where the power is needed, and testing plus a Certificate of Compliance (CCEW) at the end, because a new circuit is notifiable electrical work in NSW.
When the board is full, or still runs on ceramic fuses, adding circuits one at a time stops making sense. Replacing the board lets an electrician lay out every circuit properly, fit RCBO protection throughout and leave room for whatever comes next. Our switchboard upgrade page explains what that involves.
Sometimes the limit is the supply rather than the board. A single-phase supply can run out of capacity before the board runs out of space, particularly when an EV charger, induction cooking and ducted air conditioning arrive in the same year. For general wiring work around the home, see our residential electrician services.
Frequently asked questions
How many circuits does a 3 bedroom house need?
Most three-bedroom houses run well on about 10 to 14 circuits. That usually covers two or three lighting circuits, three to five power circuits, and dedicated circuits for the oven, cooktop, hot water and any air conditioning. An all-electric home with an EV charger will need a few more.
Is there a maximum number of circuits per safety switch?
Yes. In a home, one RCD can protect no more than three circuits under the current Wiring Rules, and a house with more than one circuit needs at least two RCDs. Many newer boards fit an RCBO to every circuit instead, which gives each circuit its own safety switch.
Should lights and power points be on separate circuits?
Yes, in almost every home. Lighting and power are wired as separate circuits with different cable and breaker ratings. Keeping them apart also means an appliance that trips the power circuit does not leave you in the dark while you find the cause.
Do I need another circuit if I add an EV charger?
Yes. An EV charger goes on its own dedicated circuit with suitable RCD protection, because it draws close to its full rating for hours at a time. Whether your board has room for that circuit, and whether your supply can carry the load, is the first thing an electrician checks.
The bottom line
The right number of circuits is the number that lets everything you own run without tripping, with lighting split so one fault never blacks out the house. If your board only has a handful of breakers, or you are planning a new kitchen, air conditioning or an EV charger, count them before you buy. Get in touch and we will look over your switchboard and tell you what it can take.