A phone charger draws about 10 watts. A laptop, maybe 60. A kettle, a serious 2,400, the biggest thing most people plug into a wall.
A home car charger draws around 7,000 watts. And it holds that, flat, for eight hours.
That second sentence is the whole story. Not the size, the duration.
Everything else in your house takes a breather
Think about what the big appliances actually do. An oven roars up to temperature, then clicks off and coasts, then clicks back on. An air conditioner does the same. A kettle pulls hard for three minutes and then it’s done. Even a hot water system heats and then sits idle for hours.
All that idle time is doing something useful that nobody thinks about: it lets the wiring cool down. Every cable, every connection, every socket face warms up while current flows and sheds that heat again in the gaps.
A car charger removes the gaps. It asks for its full current and simply holds it, through the evening, through the night, into the morning. From the wiring’s point of view, a continuous load and an on-off load of the same size are not remotely the same problem.
The bit that surprises people
A standard 10 amp powerpoint here delivers about 2,400 watts, which is notnear a kettle, it is a kettle. So a car trickle-charging from a normal socket isn’t drawing anything that powerpoint hasn’t handled a thousand times. It’s drawing it for twelve hours instead of three minutes, every night, for years. Nothing is ever overloaded. It just never gets to rest.
A local aside, because the textbook is wrong about us
Australia’s nominal supply voltage is 230 volts. That’s the number in the standards, and it’s the number you’ll get from any calculator on the internet. Out here the supply usually sits nearer 240, often 242. It’s a small difference that quietly moves every figure on this page, and it’s a decent illustration of why local knowledge isn’t sentimentality. The standard describes the country. The meter describes your street.
A cable’s rating is really a heat rating
Here’s the part that makes electricians careful and everyone else shrug. When we say a cable is “rated” for so many amps, we are not describing how much electricity can physically fit down it. Electricity isn’t water and the cable isn’t a pipe.
Current flowing through metal makes heat, always, unavoidably, as a by-product of the resistance in the conductor. The rating is simply the point beyond which the cable can no longer get rid of that heat fast enough to stay safe. It is a thermal limit wearing an electrical costume.
Which leads somewhere interesting: the rating depends on the weather. Shedding heat means shedding it into something, and how well that works depends on how hot that something already is.
Which is why this is a different question in Alice Springs
A cable in a roof space here on a January afternoon isn’t sitting in mild air. Roof cavities in the Centre get brutally hot, well beyond the outside temperature, which is already having a go at 45°C. That cable is being asked to dump its heat into air that is nearly as hot as the cable wants to be.
It’s the same reason a car overheats towing a trailer up a hill in summer and not in winter. Nothing about the engine changed. What changed is how easily it can get rid of what it makes.
So the identical install, drawn on the identical plan, is genuinely not the same install in Melbourne and in Alice Springs. Anyone who tells you a charger setup is a standard job everywhere has not thought about where the heat goes.
The car isn’t the limit. The street is.
People assume the question is which car, or which charger. It almost never is. The car will happily accept whatever it’s offered.
What’s finite is everything upstream, the supply coming into the property, the switchboard sharing it out between the aircon and the oven and the hot water, and beyond that the transformer serving the street. Add a 7,000 watt continuous load to a house and you have meaningfully changed what that house is, electrically. That’s why the first question about home charging is never about the car.
And a genuinely odd one: when matters as much as how much
Rooftop solar produces most of its power in the middle of the day and precisely none after sunset. Household demand does the opposite. It peaks in the evening, when everyone gets home, turns things on, and plugs the car in out of habit.
A car is the biggest controllable load most homes will ever have. The oven happens when dinner happens. The car genuinely does not care whether it charges at 7pm or 7am, so long as it’s full by morning. That makes it unusual: a large load that can be moved, in a system where almost nothing else can.
So what does this actually mean for you?
Mostly, that it’s worth asking before you buy the car, not after. Not because it’s difficult. It’s routine work for someone who does it, but because the answer depends on your supply, your switchboard and your roof space, and none of those are visible from a showroom.
We’re not going to tell you how to wire one. Installing or altering EV charging equipment is licensed electrical work in the Territory, and for the reasons above we think that’s entirely sensible. But we’re happy to tell you what your place can take.
Ask us what your place can takeEV charging through the Hub →Where these numbers come from
We would rather show our working than ask you to take our word for it.
- The wattages are arithmetic, not opinion. Watts = volts × amps. 10 A × 240 V = 2,400 W. A typical single-phase wall charger draws 32 A, so 32 × 240 ≈ 7,700 W. Check it on a calculator; that is the entire derivation.
- The 240–242 V figure is ours, measured here. Australia’s published nominal supply voltage is 230 V. What we actually see on meters around Alice Springs is consistently higher. We are telling you that as our own observation in this town, not quoting it as a national published figure, because it isn’t one.
- Cable ratings and heat. The method for working out how much current a cable can carry, and how that reduces as the surrounding air gets hotter, is set out in AS/NZS 3008.1.1. We have named the standard rather than reproduced any of it. it is copyright to Standards Australia, and the actual derating figures for your particular install are a job for an electrician with the current edition open, not a number to lift off a web page.
- Who may do the work. Electrical work in the Northern Territory is licensed under the Electrical Safety Act 2022 and the Electrical Safety Regulations 2024, the same legislation named on our own contractor licence. Read them at legislation.nt.gov.au rather than taking our summary of them.
- Charging times are illustrative. How long a car takes depends on its battery and how empty it is. We have used round numbers to make a point about duration, not to predict your car.
If you find something here that’s wrong, tell us and we’ll fix it. That offer is genuine. This page is only worth having if it’s right.
General explanation only, not instructions. Figures are indicative and computed at 240 V, the supply we actually measure in Alice Springs rather than the 230 V national nominal: 10 A at 240 V is about 2,400 W, and a typical single-phase 32 A home wall charger is roughly 7,700 W (commonly sold as “7 kW”). Charging times depend entirely on battery size and starting charge. Installing or altering electrical equipment in the NT must be carried out by a licensed electrician (Electrical Safety Act 2022). Sawtell Contracting NT Pty Ltd · NT Electrical Contractor Licence C 4385.