What three-phase actually is
Single-phase power arrives on one active conductor and a neutral. Three-phase arrives on three actives, each peaking at a different moment, so the load can be shared across all three. Big motors run more smoothly on it, which is why it's standard in workshops and commercial buildings.
In a house, three-phase mostly changes how much you can draw and export at once. Western Power, for example, gives a standard home on the main WA grid 63 amps on single phase, or 32 amps on each phase of a three-phase supply.
Single phase or three phase?
| Single phase | Three phase | |
|---|---|---|
| Standard supply on the main WA grid | 63 amps | 32 amps per phase |
| Home wall EV charger | Up to 7.4 kW | 11 kW or 22 kW models |
| Solar export on Ausgrid's flexible option | Up to 10 kW | Up to 30 kW |
| Solar export on SA Power Networks' Flexible Exports | Up to 10 kW | Up to 10 kW per phase |
When it's worth having
A faster EV charger. A 7 kW charger runs on single phase, and Western Power says one is permitted on a standard home connection as long as the electrician checks the total load. For 11 or 22 kW you need three phase, and the NSW Government notes that not every EV can charge at 22 kW AC anyway. In the ACT, Evoenergy recommends upgrading to three phase for a home charger over 7 kW.
A bigger solar system. Export limits are often set per phase, so three phase can let you send more to the grid. Evoenergy says upgrading to three phase can reduce the impact of the ACT's export limit of 5 kVA per phase.
Big loads at the same time. Ducted air conditioning, an induction cooktop, a pool heater and an EV charger all running together can outgrow a single-phase supply. An electrician works out your maximum demand to tell you whether that's you.
When you probably don't need it
For a lot of households, a 7 kW charger overnight is plenty. The ACT Government says a dedicated 7 kW home charger can fully charge a standard EV in about 6 to 9 hours, and that a 15 amp socket upgrade can add over 220 km of range overnight.
Some smart chargers also manage load. Evnex's home overload protection, for example, slows or stops charging when the house is drawing too much, which can make a supply upgrade unnecessary.
How an upgrade happens
A load check
A licensed electrician looks at what you run now and what you plan to add, and whether your switchboard and meter can take three phase.
The network application
Your electrician applies to the network. On CitiPower and Powercor, only a registered electrical contractor can apply, through the eConnect portal. Energex takes an Electrical Work Request, and Evoenergy starts with a Basic Design Application.
The network checks availability
Three phase has to be available at your property. Western Power confirms that before the application goes ahead, and SA Power Networks does a technical assessment and may inspect the property.
Supply and meter work
The service line and connection are changed. In NSW, that service work is done by a Level 2 Accredited Service Provider, and on networks such as Ausgrid and Endeavour Energy your retailer handles the meter.
Switchboard and certificate
The switchboard is set up for three phases, everything is tested, and you get your state's compliance certificate. On the CitiPower and Powercor networks, every supply change needs a Certificate of Electrical Safety.
How long it takes
It depends on your network. Western Power says the disconnection and reconnection takes 5 to 7 weeks once three phase availability is confirmed and the application accepted. Evoenergy gives up to 8 to 10 business days for a design and up to 25 business days for a proposed connection date.
Jemena treats an upgrade to three phase of up to 100 amps as a basic connection alteration. In Tasmania, TasNetworks may first require the installation to be brought up to current rules, which commonly means fixing low service line clearances.
What you can do, and what's licensed
You can
- List what you run now and what you plan to add.
- Check how fast your EV can actually charge on AC before choosing a 22 kW charger.
- Ask your electrician to confirm whether you have single or three phase now.
- Look at load-managing chargers as an alternative.
Leave to a licensed electrician
- Working out your maximum demand.
- Lodging the network application.
- Switchboard, mains and meter panel changes.
- Testing and the compliance certificate.
Do you really need it? Our view
We'd only go three phase for a reason we can name: a 22 kW charger the car can actually use, a solar system bigger than single phase allows, or a load calculation that says the house has outgrown its supply. If none of those apply, a 7 kW charger and a tidy switchboard usually do the job. Have an electrician who does supply upgrades work out your maximum demand before you decide.
Want a specialist to sort it?
Tell us the job and your postcode. We match the licence-checked local electrician who does this kind of work, and they call you. No ring-around, and your number goes to them alone.