The short answer is yes, you can get 3-phase power at home. Electricians can handle the electrical work but they are not allowed to change the supply, which must be done by the distribution network operator (DNO).
The extent of electrical modifications required to deliver three-phase power depends on the configuration of your property.
Most houses in the UK have a single-phase power supply, which is sufficient to power a 7.4kW EV charger but nothing more.
If you want an 11kW charger for an EV, you must upgrade to a 3-phase power supply, which requires modifications to your electrical installation.
Can you go from single-phase to 3 phase?
Yes! Any competent electrician can upgrade your property to three-phase, although electricians are not allowed to change the supply. This must be done by the distribution network operator (DNO).
We asked eco-EV Ltd, a charge point installer in Hull, about the extent of the work required to go from single-phase to three-phase.
“There are many variables involved in converting single-phase to three-phase, and that’s why you don’t see electricians publishing workflow guidance because no two jobs are the same. Having said that, there are several things you may not know about the work required.”
“The first thing to note is that anyone wanting to upgrade to a 3-phase supply would need to make an application to the DNO, but their electrician can handle the application,” says Paul Walsh, MD of eco-EV Ltd.
“Three-phase installations are structurally different to single-phase, so the existing single-phase fuse and cabling running to the property need replacing. In most homes, in the case of cabling, this means trenching [digging] back.”
“Trenching is time-intensive, sometimes at a depth of 60cm for several metres. We need a trench to make a line for the new cabling and to connect that cabling to the 3-phase supply. Sometimes you get lucky and the supply is only a few metres away, but there isn’t always a 3-phase supply located nearby.”
“Thankfully, the existing wiring in a modern house is compatible with a three-phase supply, so really, only the cabling supplying the property needs upgrading along with the distribution board.” Paul adds, “the unit needs replacing with a three-phase distribution board with RCD protection, to meet regulations.”
Next, we asked Paul to clarify the core differences between single-phase and three-phase power, to give us a better idea of the size of the project.
“Three-phase power is a four-wire circuit, with three power wires and a neutral wire. Compare that to single-phase power, which is a two-wire AC power circuit, a power wire and a neutral wire, and you can see why the work required to convert single to three-phase can be intensive.”
“The existing distribution panel needs to be removed and a new 3 phase panel added with the loads ‘balanced’ across the phases including the EV charger. This is the correct approach for a safe, professional installation.”
“Replacing a distribution board like-for-like for another is easy work for a competent electrician, but with three-phase, it’s the added complexity of the wiring that adds time to the process. It takes longer to wire up and test. Safety always comes first.”
Single to three-phase cost
Next, we asked Paul about the cost to go from single-phase to 3 phase. How much will a customer pay?
“It almost entirely depends on how far away the 3-phase supply is. If you’re a few miles away from a 3-phase supply then the project won’t be cheap. However, if we are talking up to 25m then we’re in business.”
“£4,000 including VAT for a standard conversion with up to 20m of trenching sounds reasonable,” says Paul.
“It isn’t unheard of for electricians to quote £7,000 to £15,000 for some projects, with higher price brackets for farms and larger buildings.”
“Unfortunately, if you want an 11kW or 22kW EV charger, 3-phase is absolutely necessary. We expect more people to upgrade to 3-phase with the transition to electric vehicles. It’s the price you pay for higher energy use.”
The bottom line
Yes, you can go from single to 3-phase. To upgrade to 3-phase, you need to make an application to your DNO, but your electrician can handle the application.
The cabling supplying your property needs replacing and a three-phase distribution board with RCD protection needs installing to balance the various loads.
Is upgrading to a three-phase power supply worth it? Only if you need it. A single-phase supply will power an EV charger up to 7.4kW.
We extend our thanks to ecoEV Ltd for helping us produce this resource.
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