Single-Phase to Three-Phase Power Upgrades
Air Utilities upgrades properties from single-phase to three-phase power across England, for homes and businesses that have outgrown their existing supply. A three-phase supply gives you roughly three times the capacity, which is what you need to run heavy or stacked loads such as a large heat pump, a 22kW EV charger, workshop machinery or a commercial kitchen without tripping the supply. We assess whether you genuinely need three-phase or whether a simpler upgrade will do, handle the DNO application, and manage the whole connection through to a live supply.
Single-Phase vs Three-Phase, What Is the Difference?
Most UK homes and small premises have a single-phase supply: one live conductor at 230V, usually with a 60A to 100A fuse, giving roughly 14 to 23 kVA of capacity at any one time. That is plenty for a normal household.
A three-phase supply provides three live conductors at 400V between phases, giving around three times the power over the same incoming connection. It is the standard for commercial and industrial premises, and increasingly relevant for homes adding several high-power electric loads at once.
| Single-phase | Three-phase | |
|---|---|---|
| Voltage | 230V | 400V between phases |
| Typical capacity | 14 to 23 kVA (60 to 100A) | Around three times single-phase |
| Standard for | Homes, small units | Commercial, industrial, high-load homes |
When Do You Need a Three-Phase Upgrade?
You should consider three-phase when your total demand pushes past what a single-phase supply can comfortably deliver, typically around 100A after diversity, or when you are adding specific heavy loads:
- A 22kW EV charger (a standard 7kW home charger runs fine on single-phase; only 22kW charging needs three-phase)
- A large heat pump, generally above around 8kW (roughly 32A per phase)
- Workshop or industrial machinery, motors, large HVAC, lifts
- A commercial kitchen with heavy catering equipment
- Large solar PV systems, typically above 12 kWp, to avoid phase imbalance
- Several high-power loads stacked together, for example a heat pump plus fast EV charging plus battery storage
If your existing single-phase supply trips under load, or cannot support what you want to add, that is the clearest signal to assess a three-phase upgrade.
You May Not Need Three-Phase, and We Will Tell You
Three-phase is not always the right answer, and it can cost thousands. Before recommending it, we check whether a simpler, cheaper option gives you the capacity you need. In many cases, upgrading a single-phase supply from a 60A to an 80A or 100A fuse, or upgrading the consumer unit, provides enough extra headroom at a fraction of the cost of a full three-phase conversion.
We assess your total demand first and give you an honest recommendation, because the cheapest solution that meets your needs is usually the right one. We would rather tell you a board upgrade will do than sell you a conversion you do not need.
Three-Phase Upgrade Services
- Demand assessment, to confirm whether you need three-phase or a simpler upgrade
- DNO supply upgrade applications, handled end to end
- Supply cable upgrade, including excavation and reinstatement
- Three-phase consumer unit and distribution board installation
- Circuit design and rewiring for the new loads
- Meter change coordination to a three-phase meter
- Load balancing across the three phases at commissioning
- Testing, certification and energisation
What the Upgrade Involves
A three-phase upgrade is more than a meter swap. Once the DNO approves the application, the process usually involves:
- 1
Cable replacement
The DNO excavates to expose and replace your existing single-phase supply cable with a three-phase one, which typically means digging up part of a garden, driveway or, in some cases, a footpath or road.
- 2
New board
A new three-phase consumer unit or distribution board is fitted internally.
- 3
Rewiring
Circuits are rewired and connected for the loads that need three-phase.
- 4
Meter change
The energy supplier changes the meter to a three-phase unit.
- 5
Load balancing
Loads are balanced as evenly as possible across the three phases at commissioning.
The groundworks, particularly where a road or shared driveway is involved, are usually the biggest cost and time driver.
What Affects the Cost of a Three-Phase Upgrade
- Distance from the three-phase network. If three-phase is already near your property, the job is far simpler; if not, new cable has to be run.
- Groundworks. Digging through a garden is cheaper than a driveway; a footpath or road adds council permits and traffic management.
- Shared supply cables. Where a cable is shared with neighbouring properties, the work is more complex.
- DNO reinforcement. If the local network needs upgrading to support the extra demand, this adds cost and time.
- Internal works. A new three-phase board and rewiring of circuits.
Because every property and its distance from the network is different, we do not publish fixed prices. Tell us about your property and what you want to power, and we will arrange the DNO quote and give you an accurate, no-obligation cost.
How Long Does a Three-Phase Upgrade Take?
As a general industry guide, a straightforward upgrade where three-phase is already close can be completed in a matter of weeks once the DNO application is approved, while jobs that need new cable, extensive groundworks or network reinforcement take longer. The DNO application and any network works are the main variable, so the earlier the application goes in, the sooner the upgrade completes. We submit and manage the DNO side straight away to keep the timeline as short as possible.
Our Three-Phase Upgrade Process
- 1
Demand assessment
We confirm whether you need three-phase or whether a simpler supply or board upgrade will do.
- 2
DNO application
We apply to the DNO for the three-phase supply and obtain the quote.
- 3
Supply upgrade
The single-phase cable is replaced with three-phase, including excavation and reinstatement.
- 4
Internal works
We install the three-phase board, rewire the relevant circuits and coordinate the meter change.
- 5
Commissioning
We balance the load across the phases, test, certify and energise the supply.
Frequently Asked Questions
Do I need three-phase for an EV charger?
Only for a 22kW charger. A standard 7kW home charger runs perfectly well on a single-phase supply. Most homes only need three-phase if they are adding several heavy loads together, not for EV charging alone.
Do I need three-phase for a heat pump?
Often for larger units. Industry guidance suggests heat pumps above around 8kW (roughly 32A per phase) are likely to need three-phase, but smaller units usually run on single-phase. We assess your specific unit against your existing supply.
Is it cheaper to upgrade my single-phase fuse instead?
Frequently, yes. Upgrading from a 60A to an 80A or 100A single-phase supply, or upgrading the consumer unit, can give enough extra capacity at a fraction of the cost of a full three-phase conversion. We check this before recommending three-phase.
Do you handle the DNO application?
Yes. A three-phase upgrade requires a supply upgrade application to your Distribution Network Operator, and we manage that whole process for you, including obtaining the quote and coordinating the works.
How much more does three-phase electricity cost to run?
The unit price of electricity is the same. Three-phase does not make your energy more expensive to run; it simply gives you more capacity. The cost is in the upgrade itself, not the running.
Will you dig up my driveway?
Possibly. If a new three-phase cable is needed, the DNO excavates to replace the existing supply cable, which can mean digging up part of a garden, driveway, footpath or road. We confirm the likely route and reinstatement as part of the assessment.
Get a Free Quote for Your Three-Phase Upgrade
Tell us about your property and what you want to power, and we will confirm whether you need three-phase, handle the DNO application, and manage the upgrade through to a live supply.
Let’s Power Up Your Home
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