This guide explains what three-phase electricity is, how it differs from the single-phase supply most UK homes have, and whether a household in Great Britain needs it for an EV charger, a heat pump or a larger solar and battery system. Three phase electricity in UK homes is still uncommon, so the useful question is not “is it better” but “will my single-phase supply run out first”.
Quick answer: Three phase electricity in UK homes is uncommon. The typical home has a single-phase 230 V supply with one main fuse of up to 100 A, about 23 kW. A three-phase supply gives three 230 V phases, 400 V between them, about 69 kW at 100 A per phase.
What is three phase electricity?
Three phase electricity uses three live conductors whose alternating voltages are offset by 120 degrees, plus usually a neutral, so power flows more evenly and in larger amounts than on a single live wire. In the UK and the rest of Europe it is described as 230/400 V: each phase is 230 V to neutral, and the voltage between any two phases is 400 V. The 400 V figure is 230 V multiplied by √3 (about 1.73), a result of the 120 degree offset described in the three-phase electric power article.
Three-phase is how electricity is distributed in streets and how factories, offices and farms are supplied, because it carries more power for the same amount of cable and runs large motors smoothly. In parts of Europe, such as Germany, homes routinely receive three phases. UK homes normally receive just one phase and a neutral.
The power on a balanced three-phase supply is P = √3 × line voltage × current × power factor, or equivalently three times the power on one phase. The three-phase power calculator works this out from voltage, current and power factor.
How do you know if your home has three-phase?
A three-phase home has three main fuses (or a three-pole cutout) and a three-phase meter; a single-phase home has one main fuse and a meter with one live supply. Look at the sealed cutout where the supply cable enters, usually next to the meter. Do not open or touch it: the cutout and meter belong to the network operator and the supplier, and only they may break the seals.
- One fuse carrier on the cutout: single-phase.
- Three fuse carriers side by side: three-phase.
- Consumer unit with a four-pole main switch or labels for L1, L2 and L3: three-phase.
- The rating printed on the fuse carrier (for example 60, 80 or 100) is your main fuse size in amps.
If the labels are unclear, your distribution network operator (DNO) can tell you, or a qualified electrician can check without breaking any seals.
How much more power does three-phase give?
Three phase electricity gives about three times the capacity of single-phase for the same fuse rating per phase: at 100 A that is about 69 kW instead of 23 kW. The table uses the declared UK voltage of 230 V from regulation 27 of the Electricity Safety, Quality and Continuity Regulations 2002, and a power factor of 1.
| Main fuse rating | Single-phase capacity | Three-phase capacity (same rating on each phase) | Largest single-phase load per phase |
|---|---|---|---|
| 60 A | 13.8 kW | 41.4 kW | 13.8 kW |
| 80 A | 18.4 kW | 55.2 kW | 18.4 kW |
| 100 A | 23.0 kW | 69.0 kW | 23.0 kW |
The last column is easy to miss. Three phase electricity does not let one ordinary appliance draw more than one phase can supply. A 9.5 kW electric shower still connects to a single phase. The benefit comes from spreading many loads across three phases, and from appliances built for three-phase, such as 22 kW chargers and some large heat pumps. To check what a single appliance draws, use the kW to amps calculator.
Do you need three-phase for an EV charger, heat pump or solar?
Most UK homes do not need three-phase: a 7 kW EV charger, a typical heat pump and a normal rooftop solar system all run on single-phase. Three phase electricity earns its place when you want charging above about 7.4 kW, a large heat pump that the maker supplies only as three-phase, or more solar or battery export than single-phase rules allow.
| Equipment | Single-phase at 230 V | Three-phase at 230/400 V |
|---|---|---|
| Home EV charger at 32 A | 7.36 kW | 22.08 kW (32 A per phase) |
| Home EV charger at 16 A | 3.68 kW | 11.04 kW (16 A per phase) |
| Solar or battery under G98 (up to 16 A per phase) | 3.68 kW | 11.04 kW across three phases |
| Larger solar or battery export | Apply under G99 above 3.68 kW per phase | Apply under G99 above 16 A per phase |
Two checks matter before paying for an upgrade. First, a car can only accept AC charging up to the limit of its onboard charger, so check the handbook: if it accepts 7.4 kW or 11 kW, a 22 kW charger will not charge it faster.
Second, the generation figures come from the Energy Networks Association, which states that fully type tested micro-generators up to 16 A per phase connect under EREC G98, with the DNO told within 28 days of commissioning, while larger systems follow G99. A solar array can be bigger than the inverter, so the solar inverter size calculator helps you see whether a single-phase inverter is enough.
For heat pumps, the electrical input is much smaller than the heat output, because each kWh of electricity delivers several kWh of heat. Many household heat pumps therefore fit comfortably on single-phase. The heat pump running cost calculator shows the electricity a given heat demand needs.
When does a single-phase supply run out?
A single-phase supply runs out when the loads that can run at the same moment add up to more than the main fuse: on a 100 A fuse that is about 23 kW. Electric showers, EV chargers, cookers and heat pumps are the loads that push homes towards this limit, especially on winter evenings.
Example: a home with a 100 A single-phase supply might, on a winter evening, run a 9.5 kW electric shower, a 7.4 kW EV charger, a 3 kW kettle, a 2.5 kW oven and 1.5 kW for a heat pump compressor. That totals 23.9 kW, about 104 A, just over the fuse.
In practice an electrician assesses maximum demand allowing for the fact that not everything runs at full power together, and a smart charger with load management can reduce the EV charging rate automatically when the house is busy. On a three-phase supply the same loads could be split, for example the shower on one phase (about 41 A), the charger and kettle on the second (about 45 A) and the oven and heat pump on the third (about 17 A), leaving plenty of headroom on each.
The ENA guidance on EV chargers and heat pumps says the installer must apply to the DNO through ENA Connect Direct before installation where a home’s new maximum demand is between 60 A and 100 A, so the network operator will see the numbers either way.
How do you get three-phase electricity at home?
You get three phase electricity by applying to your DNO, which upgrades the service cable and cutout, and then having a qualified electrician change the meter tails, consumer unit and circuits to suit. The steps usually run in this order:
- Ask a qualified electrician to assess your maximum demand and confirm whether a main fuse upgrade, load management or three-phase is the right answer.
- Find your DNO (the company that runs the local network, not your energy supplier) and apply for a supply change or new connection.
- Receive the DNO’s quote. The cost depends on how far the nearest three-phase cable is and whether digging or road works are needed, so quotes vary widely between streets.
- Arrange a three-phase meter with your energy supplier.
- Have the electrician install a three-phase consumer unit and reconnect circuits, balancing loads across the phases, with the work certified to BS 7671.
Before committing, ask whether a cheaper step solves the problem. Some homes still have a 60 A or 80 A main fuse, or share a looped supply with a neighbour; the ENA notes that a looped supply is one of the situations where the network operator must be contacted. Raising the fuse or unlooping the supply can release enough capacity for a 7 kW charger or heat pump without switching to three phase electricity.
Is three-phase electricity safe in a house?
Three phase electricity is safe when installed correctly, but there is 400 V between phases rather than 230 V, so all work on it must be done by a qualified electrician and comply with BS 7671. Equipment must be labelled correctly and the phases kept separate in sockets and accessories. The supply side (cutout and service cable) is the DNO’s responsibility and the meter is the supplier’s; householders and electricians must not break their seals.
Your bill is still charged per kWh, so having three phases does not by itself make electricity dearer to use; running costs depend on the energy your appliances consume. For appliance costs on any supply, the electricity cost calculator works from watts and hours.
Frequently Asked Questions
Is three-phase electricity common in UK homes?
No. Most UK homes receive a single-phase 230 V supply with one main fuse. Three-phase is usually added only where a home needs more capacity, for example for fast EV charging, a large three-phase heat pump or a bigger solar and battery system.
What voltage is three-phase in the UK?
It is 230/400 V. Each phase measures 230 V to neutral, the same as a single-phase home, and the voltage between any two phases is 400 V. Ordinary sockets and lights still run at 230 V on one phase.
Can I charge an EV at 22 kW at home?
Only with a three-phase supply, a 22 kW charger and a car whose onboard charger accepts 22 kW AC. Many cars accept less, so check the handbook first. On single-phase the practical home maximum is about 7.4 kW from a 32 A charger.
Does three-phase let me install more solar panels?
It raises the export that can connect under the simpler G98 route from 3.68 kW on one phase to 11.04 kW across three, because the limit is 16 A per phase. Larger systems on either supply can still connect under G99 with the network operator’s approval.
Who do I contact to get three-phase power?
Contact your distribution network operator, the company that runs the cables in your area, not your energy supplier. It quotes for the new service cable and cutout. A qualified electrician then adapts the wiring in your home to BS 7671.
Checked October 2026 by the Solaxyra Editorial Team. Sources: Wikipedia: three-phase electric power, ESQCR 2002 regulation 27, ENA: connecting generation, ENA: connecting EVs and heat pumps, ENA: connection FAQs.