Executive Summary
Most UK homes have a single-phase electricity connection, which naturally limits how much electricity can be used at any one time. This means that even with very low overnight electricity prices, households are physically restricted in how much energy they can consume during the six-hour off-peak period.
Only a small proportion of properties have three-phase connections, typically larger homes, farms, workshops or businesses. These properties have a much higher electrical capacity and should therefore contribute more towards maintaining the local electricity network through a higher monthly network charge.
The proposed tariff recognises these differences while keeping the electricity unit price the same for everyone.
The Difference
Single-Phase Supply
Around 95% of UK homes are connected using a single-phase electricity supply.
A typical single-phase connection is rated at around 60–100 amps, giving a maximum available power of approximately 14–23 kW.
In practice, most households will never reach this limit because electricity demand is spread across different appliances.
Typical high-power loads include:
- Heat pump
- Electric shower
- Oven and hob
- EV charger
- Battery storage charging
- Hot water cylinder
Even if electricity costs just 7.5p/kWh overnight, the physical connection limits how much energy can be consumed during the six-hour off-peak window.
Three-Phase Supply
Three-phase supplies provide approximately three times the available electrical capacity.
They are generally installed where much higher power is required, including:
- Large rural properties
- Farms
- Workshops
- Commercial premises
- Homes with exceptionally high electrical demand
Although these properties can draw more electricity, they still face practical limits:
- EV charging speeds are limited by vehicle and charger regulations.
- Battery charging is limited by the inverter rating.
- Heat pumps have fixed compressor capacities.
- Most household appliances cannot consume unlimited electricity.
Why Capacity Matters
The electricity network must be designed to support the maximum demand that customers could place on it.
A three-phase connection reserves significantly more capacity on the local network than a standard single-phase connection, even if that capacity is only used occasionally.
For this reason, it is reasonable that households with larger electrical connections contribute more towards maintaining that infrastructure.
Policy Proposal
Under this policy:
- Electricity unit prices remain identical for all households.
- Off-peak electricity remains available at 7.5p/kWh regardless of connection type.
- Peak allowance rules apply equally to everyone.
- The monthly network charge reflects the size of the electrical connection.
For example:
| Connection Type | Monthly Network Charge |
| Single phase | Standard rate |
| Three phase | Higher rate |
This reflects the additional network capacity available rather than how much electricity is actually consumed.
Why This Is Fair
This approach recognises that customers with larger electrical connections have access to greater network capacity while avoiding unnecessary complexity in electricity pricing.
It also means that:
- Most households continue to benefit from a simple, low-cost tariff.
- The overnight period cannot be exploited to consume unlimited amounts of electricity because physical equipment limits still apply.
- Larger properties contribute fairly towards the additional network infrastructure they require.
The result is a system that is simple, transparent and better aligned with the real cost of providing electricity connections, while preserving the benefits of low-cost overnight electricity for all households.