Guide
Single-phase vs three-phase EV charging at home
Single-phase and three-phase describe the electricity supply, not the plug or the battery. Three-phase can support higher AC charging power when the charger and car also support it. It is not automatically a worthwhile upgrade for a home that already meets its overnight charging needs.
In plain English
What a phase means in everyday terms
Home charging uses alternating current, or AC. A single-phase supply provides one AC phase; a three-phase supply provides three. For a consumer, the useful difference is the power the installation can make available, provided the equipment is designed and configured for that supply.
UK Power Networks describes single-phase as the standard arrangement for most domestic houses with gas central heating. It recommends an electrician assess the equipment you intend to run before deciding that three-phase is needed. This is a reason to check your own home, not a rule that every older property is single-phase or every new one is three-phase.
A smart meter, an EV tariff or a different charger app does not change the number of phases. Nor does choosing a charger with a higher number on its label. Those are separate parts of the charging arrangement.
In plain English
Find out what you have without opening equipment
Ask your installer to identify the supply during the survey. Existing connection paperwork or information from the network operator may also help. Supply equipment can give clues, but photographs alone should not be used to decide its safe capacity.
The incoming supply fuse and service head are different from the consumer unit, the household box containing circuit protection. UK Power Networks’ guidance distinguishes network-owned equipment from the equipment your electrician works on. Do not remove covers, pull fuses or disturb seals to investigate your supply.
If an upgrade is being discussed, ask the installer to identify your local DNO and explain who will contact it. The DNO operates the local electricity network. Your electricity supplier manages your retail tariff and bill; switching supplier is not a supply-phase upgrade.
In plain English
The supply, charger and car must all line up
A charging session is limited by the available supply, the charger and the car’s onboard AC charger. The onboard charger is the equipment inside the car that converts AC to the direct current stored in the battery. A car’s advertised rapid DC charging rate is not its home AC rate.
For a concrete manufacturer example, myenergi describes its single-phase zappi version as capable of up to 7.4 kW and its three-phase version as capable of up to 22 kW, vehicle permitting. Those are specifications for those versions, not a guarantee of a rate at every house.
If your car accepts 11 kW AC, a compatible 22 kW three-phase installation still cannot make it accept 22 kW. Likewise, a car limited to 7.4 kW does not gain a 22 kW capability because the supply has changed. Check the exact vehicle version rather than another model in the same range.
In plain English
Three-phase is not the only capacity question
Supply type and spare capacity are related but different. A single-phase property may need a demand assessment because of heating and appliances. A three-phase property still needs an assessment of the connected equipment and the load on each phase.
Ask whether a fixed charging limit, dynamic load balancing, or a supply change is being proposed, and why. A fuse upgrade is not necessarily a three-phase conversion. The scope should be clear before you compare prices.
UK Power Networks says some chargers can be installed and then notified, while others need supply work first. It does not publish a universal price or completion time for that work because the site and permissions affect it. Other network operators have their own process; your installer should use the one covering your property.
In plain English
Decide whether more power solves a real problem
Start with the energy you need between journeys and the time the car is parked. You rarely need to refill an entire battery every night. An occasional long journey and a daily commute can create very different charging requirements.
As an illustrative calculation, adding 30 kWh at a steady 7.4 kW takes about four hours before losses and any slowdown. At 11 kW it takes about two hours and 44 minutes. These are calculated examples, not measured charge times for a particular vehicle. If you have a long overnight window, the faster rate may not change your routine.
Two cars, short parking windows or substantial other electric demand may make a different arrangement worth investigating. Include any network work, internal electrical work and compatible equipment in the decision. Do not buy a three-phase charger on the assumption that an upgrade will be simple or that your next car will use its full output.
Your next step
What this means for you
- Have the existing supply and likely household demand assessed.
- Find your exact car’s maximum AC rate and supported phases.
- Estimate your usual charging window, not just an empty-to-full session.
- Get an itemised scope for any network and internal installation changes.
- Check who handles applications, permissions and completion paperwork.
Use the charging-time calculator to compare realistic rates. Our 7 kW versus 22 kW guide looks at charger choice; this supply assessment should come before that purchase.
Further reading
Sources
- Last reviewed
- Single-phase and three-phase electricity supplies — UK Power Networks. The distinction between supply types and why an electrician should assess the property's demand.
- Electric vehicles: cost, time and what's involved — UK Power Networks. Supply assessment, installer notification and site-specific network work. UK Power Networks' process applies in its own service area; other operators have their own arrangements.
- How to register energy devices in homes or small businesses — Department for Energy Security and Net Zero, GOV.UK. Great Britain guidance on network registration, installer responsibilities and documentation. Check current OZEV guidance for grant eligibility.
- zappi product information — myenergi. Single/three-phase zappi versions, renewable charging modes and advertised hardware pricing checked on 1 October 2026. Installation costs are separate.