Heat Pump Electrical Requirements UK

Good news: most UK homes already have the electrical capacity for a heat pump. A typical domestic air source heat pump draws 2-4kW of electricity — less than an electric shower. You need a dedicated circuit and a consumer unit that can accommodate it, but major electrical upgrades are the exception, not the rule.

This guide covers everything about the electrical side of a heat pump installation: what supply you need, what happens during the electrical work, and what it costs if upgrades are necessary.

Basic Electrical Requirements

Single Phase vs Three Phase

The vast majority of UK homes have a single-phase electrical supply, and most domestic heat pumps are designed for single-phase operation. You only need three-phase for very large heat pumps (typically above 16kW output), which are unusual in domestic settings.

Your installer will confirm during the survey whether your single-phase supply is adequate. If you have an unusually large home requiring a high-output heat pump, they will advise on options.

Consumer Unit Requirements

The heat pump needs its own dedicated MCB (miniature circuit breaker) in your consumer unit. Common scenarios:

• Modern consumer unit with spare ways: Simple — the electrician adds a new MCB. No upgrade needed
• Modern unit but no spare ways: A small upgrade or additional consumer unit may be needed (£100-£300)
• Old fuse board: May need replacing with a modern consumer unit to meet current regulations (£300-£500)

What Happens During Electrical Work

The electrical work typically happens on day three of the installation:

1. A dedicated cable is run from the consumer unit to the outdoor heat pump unit
2. A double-pole isolation switch is fitted near the outdoor unit
3. The heat pump is wired according to manufacturer specifications
4. The controls are wired and connected
5. An outdoor temperature sensor is fitted for weather compensation
6. All connections are tested and certified

The electrical work must be carried out by a Part P registered electrician — either part of the installation team or a qualified sub-contractor.

Electrical Costs

Electrical costs are included in your overall installation quote. Any additional work is identified during the survey, so there should be no surprises.

Running Cost Impact

A typical 8-10kW air source heat pump serving a three-bedroom home uses approximately 3,000-5,000 kWh of electricity per year. At the current Ofgem cap rate of 24.50p/kWh, that is roughly £735-£1,225 per year for heating and hot water.

Homeowners with solar panels can significantly reduce this figure by generating their own electricity. A typical 4kW solar system generates 3,400-4,200 kWh per year — potentially covering most or all of the heat pump's electricity consumption. See our guide on heat pump running costs for detailed analysis.

Frequently Asked Questions

Do I need a three-phase supply for a heat pump?

Most domestic heat pumps run on standard single-phase. Only very large systems for big properties may need three-phase. Your installer checks this during the survey.

Will my consumer unit need upgrading?

Sometimes. Old fuse boards or units with no spare ways may need upgrading — adding £200-£400 to the cost. This is identified during the survey.

How much electricity does a heat pump use?

A typical air source heat pump uses 3,000-5,000 kWh per year, costing roughly £735-£1,225 at current rates. This is significantly less than the gas equivalent due to the heat pump's 300%+ efficiency.