A 7kW EV charger draws about 32 amps on a single-phase supply, so it normally sits on its own dedicated circuit protected by a 32A or 40A breaker. The exact size depends on the charger's rated current, the cable size and length, and the manufacturer's instructions. The circuit also needs RCD protection rated for DC fault current.
The breaker is one of four things that have to line up before a 7kW charger can run at full speed: the breaker, the cable, the safety switch and the supply coming into the house. Most people only ask about the first, and the last is the one that most often changes the job.
How many amps does a 7kW EV charger draw?
About 30 to 32 amps, continuously, for as long as the car is charging. Power divided by voltage gives the current. Australian household supply is nominally 230 volts, and 7,000 watts divided by 230 volts is just over 30 amps. Most "7kW" wallboxes are actually 32A units, which works out to roughly 7.4kW at full output.
A kettle pulls a similar current for three minutes. An EV charger pulls it for six or eight hours overnight, often while the hot water and air conditioning are also running, so every part of the circuit is designed for that sustained load.
What size breaker and cable does each charger size need?
The breaker is matched to the charger's current and the cable is matched to the breaker. The table below shows the typical starting point for common home charger sizes. Treat it as a general guide only. The final numbers come from the charger's installation manual, the cable route and the Wiring Rules (AS/NZS 3000 and AS/NZS 3008), worked out by the electrician on site.
| Charger | Supply | Current drawn | Typical breaker |
|---|---|---|---|
| Portable 10A lead | Single phase | Up to 10A | Existing power point circuit |
| 3.6kW wallbox | Single phase | About 16A | 16A to 20A |
| 7kW wallbox | Single phase | About 32A | 32A to 40A |
| 11kW wallbox | Three phase | About 16A per phase | 16A to 20A three-pole |
| 22kW wallbox | Three phase | About 32A per phase | 32A to 40A three-pole |
For a 7kW unit the cable is commonly 6mm², stepping up to a heavier size on a long run from the switchboard to a detached garage or a driveway carport. The Wiring Rules cap how much voltage a run can lose, so distance often decides the cable size more than the charger does.
Why not just fit a bigger breaker?
The breaker is there to protect the cable, so it can never be larger than the cable allows. A breaker trips when more current flows than the cable behind it can carry safely. Fit a 50A breaker to a cable rated for 40A and the cable can overheat inside the wall while the breaker sits there doing nothing. A larger breaker does not give you faster charging. The charger sets its own maximum current, and the car's onboard charger sets another, and the slower of the two wins.
You will also see a "125% rule" quoted online, where the breaker is sized at one and a quarter times the charger's current. That comes from the American wiring code. In practice a 32A charger here often lands on a 40A breaker anyway, which is the same ballpark, but the number is set by the cable, the installation conditions and the charger's instructions rather than a fixed percentage.
Does a 7kW charger need its own circuit?
Yes. A wallbox of this size goes on a dedicated circuit running straight from the switchboard, with nothing else connected. Putting 32 amps of all-night load on a shared power point circuit would trip it or overheat it. The new circuit needs a spare position on the board, a cable route out to where you park, and the right protective device.
That device is usually a combined breaker and safety switch on one module, an RCBO, which our guide to RCBO vs RCD explains. EV circuits have an extra wrinkle: an electric car can leak a small amount of DC fault current, which an ordinary Type AC safety switch may not detect. The circuit therefore uses either a Type B RCD, or a Type A device paired with the DC leakage detection built into most modern wallboxes. Which one is right depends on the charger, and the manual will say.
Not sure your board can take a 7kW charger?
DM Electrical checks the switchboard, the cable route and the incoming supply before you buy the charger, so the quote holds. Based in Brookvale, Level 1 and Level 2 ASP accredited, across the Northern Beaches and greater Sydney.
Can my house supply handle a 7kW charger?
Often, but this is the part most worth checking, and it is separate from the charger's own breaker. Every home has a limit on how much current it can draw from the street, set by the service fuse and the size of the consumer mains. Many single-phase Sydney homes sit somewhere around 63A, some higher, some older ones lower. A 32A charger running all night uses half or more of a 63A supply on its own.
Add ducted air conditioning, an electric hot water system and an oven on a winter evening and the total can go past the limit. When that happens it is the main switch or the service fuse that gives up, not the charger circuit. There are three common answers:
- Load management. A current sensor at the switchboard tells the charger how much the house is using, and the charger slows down when the house is busy. It is often the cheapest fix.
- Turning the charger down. Most wallboxes can be set to a lower maximum current. A 7kW unit limited to 16A still charges at about 3.6kW, which is plenty for many people's daily driving.
- A bigger supply. Upgrading the consumer mains or moving to three-phase is the answer for homes with several large loads, and it is Level 2 ASP work because it touches the network connection.
If the switchboard itself is full or still has ceramic fuses, adding the charger circuit usually turns into a switchboard upgrade first. Our EV charger installation page covers how that assessment works on a real job.
Can I install the breaker myself?
No. Adding a circuit and breaker for an EV charger is electrical work that only a licensed electrician can do in NSW. It is also notifiable work, so the electrician tests the circuit when it is finished and issues a Certificate of Compliance for Electrical Work. Keep it, because insurers and buyers can ask for it and some charger warranties depend on a licensed install.
Frequently asked questions
Can a 7kW charger run on a 20A circuit?
Yes, if the charger is set to a lower maximum current to suit. Most wallboxes let the installer limit output, and a 7kW unit capped at 16A charges at about 3.6kW. That is roughly half the speed but often enough for overnight top-ups. It must never be left at full 32A output on a circuit built for 20A.
Is a 32A breaker enough for a 32A charger?
It can be, provided the breaker, the cable and the charger are all rated for that continuous load and the manufacturer allows it. Many installers step up to 40A with cable to suit, which gives the breaker margin during long overnight sessions. The charger's installation manual sets the allowed range, and the electrician works within it.
What size cable does a 7kW EV charger need?
Commonly 6mm² for a typical run from the switchboard to a garage, but it depends on the breaker size, the length of the run and how the cable is installed. Long runs to a carport or detached garage often need a heavier cable to keep voltage drop within the Wiring Rules.
Do I need three-phase power for a 7kW charger?
No. A 7kW charger is a single-phase unit and runs on a standard single-phase supply. Three-phase only becomes necessary for 11kW or 22kW chargers, or when the home's other loads leave too little headroom on a single-phase supply even with load management in place.
The bottom line
A 7kW charger usually needs a dedicated 32A or 40A circuit, cable sized for the run, and DC-aware RCD protection. Electricians fit those every week. Whether your switchboard and incoming supply can carry an all-night 32 amp load on top of everything else is the part to check before the charger arrives. Get in touch and we will check your board and supply and tell you what the install needs.