EV charger quotes can get confusing quickly because amps, kW, kWh, single-phase and three-phase all get mixed together. The short version is that amps are the current drawn from the supply, kW is the charging speed, kWh is the amount of energy going into the battery, and the charging time depends on how many kWh you need to add.
For Warrnambool homes, the best EV charger setup is not always the highest number on the charger. Where three-phase power is available and suitable, LWElectrical generally prefers it because the charging load is spread across phases. Where a charger is installed single-phase, a full 32 A setting can be a heavy continuous load on one phase and may not suit constrained supplies without proper assessment or load management.
What amps, kW and kWh mean for EV charging
Think of amps as how hard the charger is drawing current from the electrical supply. Kilowatts are the charging speed at that moment. Kilowatt-hours are the amount of energy added to the battery. If you know the kWh you want to add and the approximate charging kW, you can estimate the hours needed.
The figures below are practical estimates based on nominal Australian residential voltage. Real charging rates and times vary with vehicle model, battery size, site voltage, charger commissioning settings, battery state of charge, temperature and whether load management is installed.
- 20 A single-phase is about 4.6 kW
- 25 A single-phase is about 5.75 kW
- 32 A single-phase is about 7.4 kW
- 16 A three-phase is about 11 kW
- 32 A three-phase can be about 22 kW at the charger, but many Tesla Model 3/Y vehicles only accept about 11 kW AC
Single-phase Tesla charging: why 32 A is not always the best answer
A 32 A single-phase EV charger is commonly described as a 7.4 kW charger. That can be very useful, but it is also a large continuous load on one phase. Unlike a kettle or toaster that runs briefly, an EV charger can run for hours while the rest of the house is also using power.
That is why LWElectrical does not treat 32 A single-phase as the automatic answer. The switchboard, mains capacity, protection, existing loads, cable route and charger settings all need to be checked before deciding what current limit is sensible.
- Good fit: suitable supply capacity, correct circuit design and enough spare load allowance
- Needs caution: older switchboards, limited mains capacity, electric cooking, air conditioning, hot water or other large loads
- Poor fit without controls: constrained single-phase supplies where the charger would use most of the available current
Three-phase EV charging: why it is usually better where available
Where three-phase power is available and the installation is suitable, it is usually the preferred EV charging option. Instead of pulling the whole EV charging load from one phase, the load is shared across three phases. That can give better load balance and a more future-ready setup.
For many Tesla Model 3/Y owners, a practical three-phase setup is around 11 kW AC. A 32 A three-phase wall connector can have a higher EVSE output, but the car may still limit AC charging to about 11 kW. The exact vehicle and charger settings matter, so LWElectrical avoids promising a charge time without checking the setup.
- Spreads charging load across phases instead of loading one phase heavily
- Often gives stronger overnight charging performance where the vehicle supports it
- Can suit future electrical loads better than maxing out one single-phase circuit
What happens on homes with 40 A supply capacity
A true 40 A single-phase house supply changes the conversation. If an EV charger is set to 32 A, the charger can use 32 A out of the available 40 A while it is charging. That leaves about 8 A for the rest of the house if there is no load management or derating in place.
In everyday use, that remaining capacity can disappear quickly once an oven, cooktop, heater, air conditioner, dryer, kettle or hot water load is running. The result can be nuisance tripping, overloaded equipment concerns, or a charger that has to be turned down anyway.
- 40 A supply minus 32 A EV charging leaves about 8 A for other loads
- EV charging is a long-duration load, so maximum demand needs to be considered properly
- A site-specific assessment is more useful than simply choosing the charger maximum
Why LWElectrical may recommend 25 A, load management or a supply upgrade
Even where a property has around 40 A available per phase, LWElectrical generally does not recommend installing a 32 A single-phase Tesla charger as the preferred design. If the charger is being installed single-phase instead of three-phase, Luke would normally lean closer to a 25 A commissioned setting unless approved load management or a site-specific assessment supports higher.
A lower current setting does mean slower charging, but it can be a much better fit for the house. For many drivers, 20 A to 25 A single-phase still adds a useful amount of charge overnight while reducing stress on the electrical installation.
- Fixed derating: commissioning the charger below its maximum output
- Approved dynamic load management: reducing EV charging when the house is using more power
- Supply or switchboard upgrade assessment: useful when the customer wants maximum charging performance
What to send before quoting an EV charger installation
Clear photos and a few details make it much easier to recommend the right charger setup before booking a site visit. The goal is to understand the existing switchboard and where the charger needs to go, not just the charger brand.
LWElectrical can then advise whether three-phase is available, whether single-phase is practical, and whether a lower current limit, load management or an upgrade should be considered.
- Photos of the switchboard and meter area with covers closed and labels visible
- A photo of the preferred charger location and where the car parks
- Approximate cable route from switchboard to charger location
- Whether the property is single-phase or three-phase if known
- Vehicle model and whether you need regular overnight charging or faster top-ups
The practical LWElectrical recommendation
For most Warrnambool EV charger jobs, the practical answer is: use three-phase where it is available and suitable; do not assume 32 A single-phase is automatically the best option; and match the charger commissioning to the real switchboard and supply capacity.
That approach keeps the installation more balanced, reduces the chance of nuisance tripping, and gives the customer a setup that suits the property rather than just chasing the biggest number on the charger datasheet.
Unsure which charging setup suits your Tesla?
LWElectrical handles residential, commercial and industrial electrical work across Warrnambool and South West Victoria. Call Luke directly for practical advice and a clear next step.
Frequently asked questions
Is 32 A single-phase always safe for a Tesla charger?
No. A 32 A single-phase charger can be suitable on some sites, but it is a large continuous load and must be matched to the switchboard, mains capacity, protection, cable design and existing house loads.
Is three-phase always faster for Tesla charging?
Not always. Three-phase can provide about 11 kW at 16 A per phase and higher EVSE capacity at 32 A per phase, but many Tesla Model 3/Y vehicles cap AC charging around 11 kW. The specific vehicle and charger settings matter.
How fast is 25 A single-phase EV charging?
As a guide, 25 A single-phase is about 5.75 kW before real-world losses. Actual time depends on how many kWh the vehicle needs, the car, the charger settings and site conditions.
Can LWElectrical install a charger and limit it below maximum output?
Yes, where the charger and circuit design support it, the commissioned current can be set below the charger maximum. That is often useful on constrained single-phase supplies.
What photos should I send for an EV charger quote?
Send photos of the switchboard and meter area, the proposed charger location, where the car parks, and any labels showing main switch or supply details. Also include the vehicle model and whether you know if the home is single-phase or three-phase.