Your installer mentioned single-phase. The spec sheet says three-phase. Someone on the forum swears three-phase is the only sensible option. If you’ve never had to think about which type of electricity supply your home runs on, now suddenly seems like a very inconvenient moment to start. The good news is that for most UK homes, the answer is straightforward, the implications are simple, and the only real question is whether your cable should be three-phase, not your supply.
What single-phase and three-phase electricity actually mean
The UK grid delivers electricity to homes and businesses as alternating current (AC). The difference between single-phase and three-phase is simply how many live conductors carry that current from the distribution network to your property.
Single-phase uses one live conductor (L1) at 230V relative to neutral. It is the standard domestic supply for the vast majority of UK homes, and it’s what powers every plug socket, kettle, washing machine, and lighting circuit in a typical house.
Three-phase uses three live conductors (L1, L2, L3) offset by 120 degrees, delivering 400V line-to-line. It is the standard supply for industrial equipment, commercial buildings, and large installations, and the reason industrial motors, large commercial HVAC systems, and commercial workshop equipment often run on three-phase.
For EV charging, the calculation is straightforward:
- Single-phase at 32A: 32A × 230V = 7,360W ≈ 7.4kW
- Three-phase at 32A: 32A × 400V × √3 = 22,170W ≈ 22kW
The “32A” cap on EV circuits comes from BS 7671:2018+A2:2022 (IET Wiring Regulations), Section 722, which sets the electrical requirements for EV charging installations. This is why 7.4kW is the ceiling for single-phase home charging, not an arbitrary product decision.
- Left panel (single-phase): 1 live wire (L1), 1 neutral (N), 1 earth (PE) → 230V → 32A → 7.4kW wallbox → Type 2 cable → car. Right panel (three-phase): 3 live wires (L1, L2, L3), 1 neutral (N), 1 earth (PE) → 400V → 32A → 22kW wallbox → Type 2 cable → car. Label power outputs clearly: 7.4kW max and 22kW max.
How to tell which supply your home has
Start at your consumer unit (commonly called the fuse board or distribution board). This is usually in the hallway, under the stairs, or in a utility room.
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Single-phase: You will see one main incoming isolator or main fuse, a single large switch or cartridge fuse at the top of the consumer unit where power enters from the meter. This is the normal setup for UK homes.
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Three-phase: You will see three main fuses or three isolators side-by-side at the incoming position. Often these are three 100A cartridge fuses. This is uncommon in UK homes.
If your electricity meter is accessible, a three-phase meter has three sets of terminals on the supply side. Most domestic meters are single-phase and clearly show one line input.
When in doubt, call your energy supplier or Distribution Network Operator (DNO). They can confirm your supply type from records, with no visit needed. Approximately 95-97% of UK residential properties are single-phase. If you live in a standard terraced, semi-detached, or detached house in a residential street, you are almost certainly single-phase.
What each supply means for EV charging speed
The practical outcome of your supply type for EV charging is captured in this comparison:
- Four bars. Single-phase 16A: 3.7kW; Single-phase 32A: 7.4kW (label: most UK homes); Three-phase 16A: 11kW (label: 11kW public AC posts); Three-phase 32A: 22kW (label: 22kW destination chargers). Y-axis: kW. X-axis: supply type + current.
The 7.4kW ceiling for a single-phase home isn’t a limitation of the wallbox you choose. It’s a physical ceiling set by the supply itself. Any wallbox rated “7kW” and any wallbox rated “22kW” will both deliver the same 7.4kW on a single-phase supply. Spending more on a higher-rated wallbox does not break through the single-phase ceiling.
For most EV owners, 7.4kW overnight charging is entirely sufficient. A car with a 60kWh battery and 7.4kW charging refills from 20% to 80% in approximately 5 hours, well within a typical overnight window. To see what charging speed to expect for your specific car, our guide on amps and kilowatts in EV charging maps out the relationship in detail.
Can you upgrade to three-phase for faster EV charging?
Yes, but the cost is rarely justified for EV charging alone.
Upgrading a single-phase residential supply to three-phase requires:
- Confirming that a three-phase network cable runs close enough to your property (if it does not, the DNO will need to extend the network, dramatically increasing cost).
- A formal DNO application and works.
- New metering equipment.
- Updated consumer unit wiring.
Typical cost range: £3,500 to £15,000, excluding VAT. The lower end applies where a three-phase cable already runs close to the property; the upper end applies where network extension is needed. Timescales typically run to several months from application.
Beyond the cost, there is a further constraint: even with a three-phase supply, charging at 22kW requires a car with an onboard AC charger rated at 22kW. Most popular UK EVs cap AC charging well below that: the Tesla Model 3 at 11kW, the Volkswagen ID.4 at 11kW, the Kia EV6 at 11kW, the Nissan Leaf at 6.6kW. The realistic maximum gain for most UK EV owners on three-phase would be 11kW rather than 22kW, still a meaningful speed increase, but one that needs to be weighed against a potentially five-figure infrastructure upgrade.
For a detailed breakdown of the 7kW vs 22kW decision, and a car-by-car table of what onboard AC chargers actually accept, see our 7kW vs 22kW cable guide.
Why your cable matters even if your home is single-phase
This is the point that tends to surprise people: the phase rating of your cable is separate from the phase rating of your home supply.
A three-phase (22kW) Type 2 cable connects to a single-phase wallbox and charges at 7.4kW exactly as normal. Only the L1, N, and PE pins carry current; L2 and L3 sit idle. IEC 62196-2, the AC connector standard defining the Type 2 format, specifies both 5-pin (single-phase) and 7-pin (three-phase) variants as the same external housing, with the same car-side connector.
This backward compatibility means:
- At your single-phase home wallbox: 7.4kW, identical to a single-phase cable.
- At a public 11kW AC destination post: up to 11kW (if your car supports it). A single-phase cable hard-limits you to 7.4kW here.
- At a public 22kW AC destination post: up to 22kW (if your car supports it). A single-phase cable caps you at 7.4kW.
The ~£20 price difference between a single-phase and three-phase cable of the same length is, effectively, the cost of never having to think about this problem again. You carry one cable. It works on every Type 2 socket in the UK regardless of its phase rating.
Which cars actually benefit from three-phase supply?
Most UK EVs with an 11kW onboard AC charger (Tesla Model 3, Tesla Model Y, Volkswagen ID.4, Kia EV6, Hyundai Ioniq 5, BMW i3, Polestar 2) will charge at their full 11kW speed on a three-phase supply, compared to 7.4kW on single-phase. This is a real 49% speed increase at home if you have three-phase.
Cars with 22kW onboard AC chargers, among them the Renault Zoe R135, certain Audi Q8 e-tron variants and the Smart EQ ForTwo, can charge at the full 22kW on a three-phase supply.
Cars capped at 7.4kW or below, such as the Nissan Leaf (40kWh at 6.6kW, 62kWh at 6.6kW) and certain older PHEVs, see no benefit from three-phase at home regardless of supply.
A note on a commonly repeated error: the BMW i3 is frequently misidentified as a Type 1 car. It is not. All UK-market BMW i3 models use a Type 2 (IEC 62196-2) inlet and typically have an 11kW onboard AC charger, benefiting from three-phase supply if available.
Frequently asked questions
Is my home single-phase or three-phase?
Almost certainly single-phase. Around 95-97% of UK residential properties are single-phase. Check your consumer unit: one main incoming fuse or isolator means single-phase; three main fuses side-by-side means three-phase. Your DNO can confirm from their records if you’re unsure.
What is the maximum home EV charging speed on single-phase supply?
7.4kW. That is the product of 32A (the maximum for a domestic EV circuit under BS 7671:2018+A2:2022, Section 722) and 230V (single-phase line voltage). No wallbox or cable can exceed this on a single-phase supply.
What does three-phase electricity deliver at 32A?
22kW, calculated as 32A × 400V × √3 ≈ 22kW. On a 16A three-phase circuit the output is approximately 11kW.
How much does a three-phase electricity upgrade cost in the UK?
Typically £3,500-£15,000 excluding VAT, depending on how close your property is to the nearest three-phase network. The DNO application and works typically take several months. Most homeowners find this cost difficult to justify for EV charging speed alone.
Does a three-phase cable work on a single-phase home wallbox?
Yes, completely. A three-phase (22kW) Type 2 cable plugs into any single-phase Type 2 wallbox and charges at 7.4kW. The extra L2 and L3 conductors carry no current. This backward compatibility is why buying a three-phase cable makes sense even on a single-phase supply.
Can I charge at 22kW AC at home if I have three-phase?
Only if your car’s onboard AC charger accepts 22kW. Most popular UK EVs (Tesla Model 3/Y, VW ID.4, Kia EV6, Hyundai Ioniq 5) top out at 11kW AC. Only a small number of models accept the full 22kW AC rate.