Single-phase vs three-phase EV charging: which do you need?
How single-phase and three-phase supplies affect home EV charging in South Africa, what your car's onboard charger allows, and when upgrading your supply or DB board is worth the cost.
By StrataCharge teamPublished 5 min read
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Why the phase of your supply matters
Your home’s electricity supply is either single-phase or three-phase. That one detail sets the ceiling on how fast a home AC charger can run, so it’s the first thing to check before you buy.
- Single-phase is one live conductor at about 230 V. On a 32 A circuit, that gives a maximum of about 7.4 kW.
- Three-phase is three live conductors. On 32 A per phase, a charger can deliver up to about 22 kW. At 16 A per phase, it gives about 11 kW.
About 70% of South African homes are on single-phase supplies of 60 to 80 A, which in practice caps home charging at about 7 kW, as reported by TopAuto (20 May 2026).
What your car can actually accept
The charger on the wall doesn’t do the charging on AC. It supplies power safely, and the car’s onboard charger converts it to DC for the battery. The onboard charger has its own limit, and the slower of the two sets the speed.
| Your supply | Your car’s onboard charger | What you’ll get (approx.) |
|---|---|---|
| Single-phase | 7.4 kW or higher | Up to about 7.4 kW |
| Three-phase | 11 kW | Up to about 11 kW |
| Three-phase | 22 kW | Up to about 22 kW |
| Three-phase | Single-phase only (some PHEVs and older EVs) | Single-phase rate, often 3.7 to 7.4 kW |
Check your car’s specification sheet for its “AC charging” figure. Many plug-in hybrids and some smaller EVs only accept single-phase AC, so a three-phase charger adds nothing for them.
How much range does each option add?
As a rule of thumb, a mid-sized EV uses roughly [X] kWh per 100 km. [Confirm figure for typical SA models.] On that basis:
- 3.7 kW (16 A single-phase, or a portable cable): about [X] km of range per hour.
- 7.4 kW (32 A single-phase): about [X] km per hour.
- 11 kW (three-phase): about [X] km per hour.
- 22 kW (three-phase, if the car accepts it): about [X] km per hour.
Most cars sit in the garage for 10 hours or more overnight. Even at 7.4 kW, that adds far more range than an average daily commute uses. For most households, single-phase at about 7 kW is enough. Our charger sizing tool does this calculation for your car and driving.
When three-phase is worth it
Three-phase charging makes sense when:
- Your home is already three-phase and your car accepts 11 kW or 22 kW. The extra cost over a single-phase install is modest.
- Two or more EVs share one supply. A three-phase supply balances the load better and leaves more headroom for the house.
- You drive long distances most days, or the car is only home for short periods.
- It’s a small business or a home office with a fleet vehicle, where turnaround time matters.
It’s usually not worth it for a single car that’s home overnight and does normal commuting, or for a plug-in hybrid with a single-phase onboard charger.
What a supply upgrade involves
Going from single-phase to three-phase isn’t just an electrician’s job. Three-phase may need a municipal application and a new meter, as reported by cars.co.za (2026). In practice, that means:
- An application to your supplier: your municipality (for example City Power, City of Tshwane, City of Cape Town or eThekwini) or Eskom, depending on where you live.
- Supply and connection fees set by the supplier, which vary widely by area and capacity.
- A new meter and possibly a new service cable from the street or the kiosk.
- DB board changes to distribute three phases safely.
- A Certificate of Compliance for the new and altered work.
Timelines depend on the supplier and can run from weeks to months. Get the supplier’s quote before committing to a three-phase charger.
DB board upgrades: the step in between
Sometimes the issue isn’t the phase but the board. An older DB board may have no space for another breaker, an undersized main switch or outdated earth leakage protection. A smaller upgrade, such as a sub-board or a new main switch within your existing supply, is often enough to add a 7 kW charger safely.
If your supply is tight, load management is another option. A smart charger measures what the house is using and reduces its own draw when the geyser, stove and pool pump are all running. That avoids tripping the main breaker without paying for a bigger supply.
Common mistakes to avoid
- Buying a 22 kW charger for a single-phase home. It will only deliver single-phase power, so you pay for capacity you can’t use.
- Ignoring the car’s limit. A three-phase charger won’t speed up a car whose onboard charger is single-phase only.
- Undersizing the cable. If a three-phase upgrade is likely in the next few years, size the cable for it now. Re-running cable later costs far more.
- Forgetting the rest of the house. A charger that runs flat out while the geyser, stove and pool pump are on can trip your main breaker. Load management or a lower charging current solves this.
How to decide
- Check your supply: single-phase or three-phase, and the main breaker size.
- Check your car: its maximum AC charging rate and whether it accepts three-phase.
- Check your driving: daily kilometres and how long the car is parked at home.
- Pick the charger that matches the lowest of the three. Browse our home and wallbox chargers.
- Get the site checked. Our site assessment confirms supply, DB board capacity and cable route, and our installation service handles the rest, including the CoC.
Not sure where you stand? Send us photos of your DB board and meter on WhatsApp or by email, and we’ll tell you what your home can support.