Three-Phase Power

Why three-phase exists

Single-phase power works well for residential loads. But large motors, industrial equipment, and commercial-scale systems are more efficient on three-phase supply - the three sinusoidal waves, offset 120° from each other, create a smoother and more powerful combined current. It also allows more power to be transmitted through the same cable size.

In Australia, three-phase supply is standard for commercial buildings, new housing estates in some states, and homes with large installed loads (ducted HVAC, workshop equipment). The incoming supply at street level is almost always three-phase; whether that runs to your house or just single-phase is a local distribution decision.

What it enables for EV charging

Three-phase opens up faster AC charging options that single-phase can’t reach:

• 11 kW (3-phase, 16A): Charges a 60 kWh battery in about 6 hours
• 22 kW (3-phase, 32A): Charges the same battery in around 3 hours

However, this only matters if your car’s OBC supports three-phase input. Most affordable EVs currently sold in Australia have single-phase OBCs rated at 7.4 kW - they will charge at 7.4 kW even if connected to a 22 kW three-phase charger.

Vehicles with three-phase OBCs available in Australia include the Tesla Model 3 (11 kW), IONIQ 6 (11 kW), BYD Seal (11 kW), and Porsche Taycan (up to 22 kW with the optional OBC). If you have three-phase supply at home and intend to own a vehicle with an 11 kW OBC, installing an 11 kW three-phase wallbox makes sense.

Three-phase at commercial charging sites

Most shopping centre, hotel, and office car park AC chargers operate on three-phase. A 22 kW charger at a shopping centre is very common - and genuinely useful if your car has an 11 kW or 22 kW OBC. Parking for 2–3 hours while doing your shopping can add 20–60 kWh depending on the charger and vehicle combination.

Checking if your home has three-phase

Look at the main switchboard. Single-phase homes have one main switch and one active terminal. Three-phase homes have three active terminals (often labelled L1, L2, L3 or A, B, C) and typically a 3-pole main switch. If you’re unsure, an electrician can confirm in five minutes.