Here's the numbers that matter… a standard single-phase connection in Australia is rated at 63 amps. At 240 volts, that's roughly 15,000 watts (15kW) of continuous capacity. Older, inner-city homes that haven't been renovated sometimes sit on 32 or 40 amp connections instead, which is around 7,700 to 9,600 watts (7.7kW - 9.6kW). Either way, it's more than enough headroom than most people assume once you look at what an all-electric home actually draws, rather than what it’s appliances are rated for.
Rather than talk in hypotheticals, I'll use my own house as an example. It's about as demanding a test case as you'll find. I'm fully electric (obviously!), including a double oven, 90cm induction cooktop, a heat pump hot water system, a 7kW split in the lounge, a 2.5kW split in the bedroom, and two EVs sharing a 12.5kW DC charger integrated into my home battery stack. All of it runs on a single-phase connection and i've never tripped the main switch.
Case Study
Appliance: Induction cooktop (90cm, 5 zone)
Rated Size: 10.8kW
Actual Draw: 2-3kW when cooking
Appliance: Double Oven
Rated Size: 6.5kW combined
Actual Draw: 2kW with one oven running
Appliance: Hot water heat pump (no element)
Rated Size: 0.55A
Actual Draw: 0.55kW (timed to solar surplus or overnight)
Appliance: Split system (lounge, 7.1kW)
Rated Size: 2kW
Actual Draw: 2kW
Appliance: Split system (bedroom, 2.5kW)
Rated Size: 0.6kW
Actual Draw: 0.5kW
Appliance: General Power (Fridge, washer, TV ect)
Rated Size: -
Actual Draw: 1-2kW with occasional spikes of 3-4kW
Appliance: EV Charger
Rated Size: 12.5kW
Actual Draw: 12.5kW (timed to solar surplus or overnight)
Total Average
Rated size: ~33kW (139A)
Actual draw: ~9.3kW (39A)
Once you add the maximum rated figures up you get roughly 33kW, or about 138A. That's more than double what a 63A connection can deliver. Add up what the appliances are actually using at any normal moment (a few hobs on the cooktop, one oven on, the splits ticking over, hot water and general power in the background, and it comes to around 9kW, which is under 40 amps. That's before the EV charger even factors in, because it's timed to run when the rest of the house isn't under load. It’s either running off solar surplus during the day, or overnight. Even on the rare day everything lines up at once, there's still headroom under the 15,000 watt ceiling of a standard connection.
That's not a fluke by the way. It's the logic built into AS/NZS 3000, the wiring standard, which applies diversity factors because a household never runs every appliance at maximum output at the same time. My own house is the proof. If a house running two EVs off one charger, a full electric kitchen, and heating and cooling can sit comfortably on single-phase. Even the average home electrifying with one car, one cooktop and a couple of splits has plenty of room to spare.
Of course, none of this means three-phase is pointless or not required. If you're heating a pool and spa in a large, older, poorly insulated home, want both EVs charging at full capacity on demand rather than timed around solar, or want a much bigger solar and battery system than a single-phase inverter allows, three-phase earns it’s cost. And if you're building new, adding it at around $2,000 is cheap enough that there's no harm future-proofing. But that's a different conversation to "I want to get off gas."
If someone's quoting you a three-phase upgrade as a precondition for electrifying an average home, ask them to explain their working. In most cases, the numbers and my own home as the example, will show you don't need to spend the money.
