The short answer
Most fixed air conditioners, especially larger split systems and ducted units, are wired on their own dedicated circuit from the switchboard, sized to what the manufacturer's installation instructions call for. Running a new circuit is electrical wiring work, so in NSW it must be done by a licensed electrician. The new circuit needs a 30 mA safety switch (RCD or RCBO) at the switchboard, and Type AC RCDs can no longer be used in new work in NSW. Before you buy, check that your switchboard has room for the new circuit and that your supply can handle the extra load. A small plug-in unit is different: it plugs into a power point like any appliance.
Why aircon gets its own circuit
An air conditioner is one of the biggest loads in most Wagga homes. Wagga Wagga's mean January maximum is 31.9 °C (Bureau of Meteorology, Wagga Wagga AMO), and the mean July minimum is 2.8 °C, so reverse-cycle units often run hard in both summer and winter.
Putting a big unit on a circuit shared with the kitchen or other power points risks overloading and nuisance tripping, right when you need it most. A dedicated circuit gives the unit the supply it was designed for, and if something goes wrong with the aircon, it doesn't take out the rest of the house.
The manufacturer's installation instructions set out what each unit needs, such as the circuit size and protection. Nelson works from those and the Wiring Rules, AS/NZS 3000:2018.
Split system vs ducted vs portable
| Type | Electrical side |
|---|---|
| Portable / window unit with a plug | An appliance. Plugs into a power point. No electrician needed for the unit itself. |
| Small split system | Usually a dedicated circuit. Licensed electrician. |
| Large split system | Dedicated circuit. Licensed electrician. May affect maximum demand. |
| Ducted reverse-cycle | Dedicated circuit, single or three-phase depending on the unit. Licensed electrician. Check supply capacity first. |
| Multiple units | Each typically on its own circuit. Check switchboard room and total load. |
Safety switches on the new circuit
Under AS/NZS 3000:2018, domestic and residential installations require 30 mA RCD protection on final subcircuits, and when a new circuit is added to an existing home, that circuit must get RCD protection at the switchboard where the circuit starts.
Other points:
- Type AC RCDs are banned in new work in NSW since 1 May 2023, and can't be sold in NSW. New circuits use Type A or better.
- An RCBO combines an RCD and circuit breaker for one circuit, so if the aircon trips, only the aircon goes off. On a shared RCD, a fault on one circuit trips the others with it. See RCD vs RCBO.
- Adding the aircon circuit doesn't mean upgrading the whole house. Only the new circuit needs an RCD, unless the switchboard is replaced.
Does your switchboard have room?
This is the most common surprise. Before you commit to a unit, open the switchboard and look for:
- spare space for a new circuit breaker or RCBO
- ceramic fuses rather than circuit breakers
- a black or dark "pitch" backing board, which may contain asbestos if made before 1987
- scorch marks, buzzing or a burning smell
If there's no room, or the board is old, you may need a switchboard upgrade first or at the same time. When a switchboard is replaced, every applicable final subcircuit on it must get RCD protection. Get a switchboard estimate online, or read signs you need a switchboard upgrade.
Can your supply handle it?
A big ducted system, or several splits plus an EV charger and pool pump, adds up. Under the Service and Installation Rules of NSW, if an alteration would push your maximum demand above what your connection agreement allows, you need a written connection application to Essential Energy, including a maximum demand calculation to AS/NZS 3000.
Supplies up to 100 A per phase can be single, two or three-phase. Above 100 A per phase, supply must be three-phase. Some larger units are made for three-phase supply, so check the unit's specifications. If you need three-phase and don't have it, upgrading the supply involves Essential Energy and an Accredited Service Provider (ASP). See three-phase power.
Who does what on an aircon install
An aircon install usually has two parts:
- The electrical side: new circuit from the switchboard, protection, connection to the unit, testing and the Certificate of Compliance for Electrical Work (CCEW). That's licensed electrician work.
- The mechanical and refrigeration side: mounting the units, running the refrigerant pipes and drains, and commissioning. That's done by an air conditioning installer.
Some customers get the installer and electrician to coordinate; others book them separately. Either way, the electrical work must be done by a licensed electrician and tested, and a CCEW lodged through the Building Commission NSW eCert portal no later than 7 days after the test.
Nelson handles the electrical side for heating and cooling. If you've already bought a unit, send the model and where you want it, plus a photo of your switchboard.
Heat pump hot water and other big loads
If you're also adding a heat pump hot water system, NSW Advisory Note 1/2025 says a new or upgraded circuit for it must use a Type A RCD. It's worth planning both together so the switchboard is set up once.
What affects the price
The price depends on the distance from the switchboard to the unit, the switchboard's condition and whether it has room, the size of the unit, and how far you are from Wagga (travel is free close to town and charged further out). Call Nelson on 0416 085 416 or send the job through for a written quote before any work starts. If the board needs replacing, the switchboard estimate gives you a figure for that part.
Common questions
Does a split system air conditioner need a dedicated circuit?
Most do, especially larger units. The manufacturer's installation instructions set out what the unit needs. A licensed electrician will size the circuit and protection to suit.
Can I plug my air conditioner into a power point?
Portable and window units with a plug are designed to plug into a power point. Fixed split and ducted systems are wired in by a licensed electrician.
Does the aircon circuit need a safety switch?
Yes. A new circuit in a home needs 30 mA RCD protection at the switchboard. Type AC RCDs can't be used in new work in NSW, so it'll be Type A or better.
My switchboard is full. Can I still get aircon?
Possibly, but you may need a switchboard upgrade first. If the board is replaced, all applicable circuits get safety switch protection. Use the switchboard estimate or ask Nelson to look at it.
Who provides the certificate for the aircon wiring?
The licensed electrician who tests the work lodges the CCEW through the Building Commission NSW eCert portal, no later than 7 days after the test. You get a copy by email.