Most households in the UK will have a single phase supply and meter. Most commercial and industrial buildings will have a three phase supply and meter. This is because single phased supplies can supply only a limited amount of energy and are therefore not suitable for buildings with a larger electricity demand.
Larger homes with devices that result in a large electricity demand may require more power than a single phase supply can provide and will need a three phase supply. This is usually the case when a home has a multiple high demand devices, such as electric heating (e.g. electric panels, storage heaters, immersions or a heat pump), a car charger, electric ovens and induction hobs, batteries etc.
Increasingly, larger new homes are being connected to the National Grid with three phase supplies due to the trend towards electrification of heating and electric cars. Many older homes may also need their single phase electricity supplies upgrading to three phase supplies when they switch to electric heating as part of retrofits and decarbonisation works. The designers/installers of the systems and local electricity networks should decide whether the existing supply is sufficient and take care of any upgrade work, if necessary.
All electricity is distributed through the National Grid at three phase as this allows larger amounts of electricity to be moved around the country more efficiently. This can be thought of as three separate streams of electricity travelling down a single cable, all sightly 'out of phase' with each other. A single phase supply will tap into only one of these three phases.
A single phase supply is connected at 230 or 240 volts via two wires whereas a three phase connection is connected at 400 or 415 volts by three active wires, one for each ‘phase’, and one neutral.
Even if your house has a three phase supply, the majority of your equipment will still only work off one of the phases, with only larger devices such as large car chargers, batteries and heat pumps making use of all three phases.