Guide
Three phase for EV charging and heat pumps: when it is needed
Updated
EV chargepoints, heat pumps and battery storage all land on the same incoming supply, and they tend to arrive in the same eighteen months.
What actually triggers the need
- Several chargepoints on one site. One 7kW point is a single phase job on most properties. A row of them at a workplace or a block is a capacity question, and three phase both raises the ceiling and lets the load be spread across phases.
- A 22kW AC chargepoint. 22kW AC draws across three phases, so it is not available on a single phase supply at all. It also only helps if the vehicle's onboard AC charger accepts more than 7kW, which is stated in the handbook.
- Heat pumps plus everything else. A heat pump adds a sustained electrical load through the coldest part of the year, at exactly the hours the rest of the property is busiest. It is the combination rather than the heat pump alone that usually breaks the supply.
- Battery storage and generation. Export arrangements and inverter sizing interact with the connection, and larger installations are a network application in their own right.
Sequence the application properly
- Get a load assessment covering everything planned, not just the item in front of you. Adding the heat pump application six months after the charger application is how a site pays for two rounds of work.
- Ask the network operator what capacity is available at the property before you specify equipment.
- Apply for the connection, and expect terms within three months: Ofgem requires the operator to give you terms for an energy connection within three months, including how it works out the charge.
- Ask for the quotation split into contestable and non-contestable work, which Ofgem specifically advises, and price the contestable part competitively.
- Arrange the meter with your supplier alongside the connection rather than after it, which is Ofgem's advice for avoiding delays.
Load management is not a fudge
Where the connection quote is large, controlled charging and heat pump curtailment can defer or avoid the upgrade entirely, and modern chargepoints are built for it. The Electric Vehicles (Smart Charge Points) Regulations 2021 require charge points sold for private use in Great Britain to have smart functionality that can increase, decrease or reschedule the flow of electricity, so the capability is in the hardware by law. Compare a properly designed load-managed scheme against the connection quote before committing to either.
Budget the internal work too
A three phase supply arriving at the property does not by itself power anything. New main switchgear, a three phase board, earthing arrangements and submains to the charging or plant location are all your contractor's scope, quoted separately from the connection. Get both numbers before you make the decision, because a modest connection quote with a large internal bill behind it is a common surprise.
Ofgem's guidance on connections, quotes and what your network operator must do is the plainest public source on the process, and it is linked in the sources below.