A heat pump electrical upgrade costs between £800 and £4,500
If you are planning to install a heat pump, the headline cost you see from installers rarely includes the electrical work needed to make it run safely. For many homes, particularly those built before 2000, upgrading the electrical supply can add a significant sum to the total bill.
The typical cost range for upgrading a home’s electrical supply to accommodate a heat pump is £800 to £4,500, with the upper end covering a full mains cable replacement from the street to the consumer unit.
The upgrade is separate from the heat pump installation cost because the heat pump installer, often an MCS-certified heating engineer, is not usually an NICEIC-registered electrician. The electrical work must comply with Part P of the Building Regulations and the IET Wiring Regulations (BS 7671), which are distinct from the heat pump’s own installation standard (MIS 3005).
A simple consumer unit (fuse box) upgrade, where the existing board is swapped for one with a dedicated heat pump circuit and a spare way, typically costs £800–£1,200. A service head upgrade, where the main fuse supplied by the Distribution Network Operator (DNO) is increased from 60 amps to 80 or 100 amps, adds £500–£1,500. The most expensive option is a full mains cable upgrade from the street to the house, which can run £2,500–£4,500 if trenching or drilling through foundations is required.
According to the Energy Saving Trust’s 2026 heat pump cost report, the average total cost for a complete heat pump installation including all electrical work is now £12,000–£15,000 (Energy Saving Trust, 2026). Of that, the heat pump unit and cylinder account for roughly £7,000–£9,000, leaving the electrical upgrade as a substantial secondary cost.
The three electrical components that determine upgrade need and cost
The electrical requirements for a heat pump are not complicated, but they are specific. Three main components determine whether your home needs an upgrade: the main fuse capacity, the consumer unit configuration, and the earthing arrangement.
Main fuse capacity. The standard domestic main fuse in the UK is 60 amps or 80 amps. A heat pump draws between 2 kW and 7 kW of electrical load at peak, depending on its size and whether it has an integrated immersion heater. That equates to roughly 9 to 30 amps at 230 volts. When added to a typical home load, lights, cooking, shower, washing machine, a 60-amp fuse is often insufficient. The IET Wiring Regulations (BS 7671, 18th Edition Amendment 2) require that the main fuse and supply cable be rated to carry the total expected load without exceeding 80% of the fuse’s capacity under normal conditions (IET Wiring Regulations, 2026).
Consumer unit capacity. The consumer unit (fuse box) must have a dedicated circuit breaker for the heat pump, with a “spare way” to install it. Many older fuse boxes have no spare ways, or have only a single row of fuse holders that cannot accept a modern MCB (miniature circuit breaker). If no spare way exists, the electrician must either install a new consumer unit or add a sub-board, both of which add cost.
Earthing. Heat pumps require a good earth connection to protect against electrical faults. Older homes, especially those with a TN-S (separate earth) or TT (earth rod) system, may need an earth upgrade to meet the 0.1 ohm or less resistance required by BS 7671. This is often included in a consumer unit upgrade but can add £200–£400 if a new earth rod or bonding is needed.
Ofgem’s guidance on electric vehicle and heat pump charging states that homes with a main fuse of 60 amps or less should arrange a DNO upgrade before installing a heat pump (Ofgem, 2026).
Quick numbers cost, savings, and payback for a heat pump electrical upgrade
| Upgrade type | Typical cost (GBP) | Typical time (hours) | Impact on heat pump efficiency | BUS grant eligibility |
|---|---|---|---|---|
| Service head upgrade (fuse increase) | £500–£1,500 | 2–4 | None | No |
| Consumer unit upgrade | £800–£1,200 | 3–5 | None | No |
| Full mains cable upgrade (street to house) | £2,500–£4,500 | 4–8 | None | No |
| Dedicated circuit only (no other upgrade) | £300–£600 | 1–3 | None | No |
Source: Energy Saving Trust, “Heat Pump Installation Costs” (2026) (Energy Saving Trust, 2026); DESNZ, “Boiler Upgrade Scheme: Technical Guidance” (2026) (DESNZ, 2026).
Note that none of these electrical upgrades are eligible for the Boiler Upgrade Scheme grant. Understanding the Boiler Upgrade Scheme 2026
The direct answer a heat pump electrical upgrade is needed if your main fuse is 60 amps or less, or your consumer unit has no spare way
The single most common reason for an electrical upgrade is insufficient capacity at the main fuse. If your main fuse is rated at 60 amps or less, it cannot safely supply a heat pump alongside a standard home load of lights, cooking, shower, and appliances without tripping or overheating.
The Energy Networks Association’s Heat Pump Connection Guide (2026) states that a 60-amp fuse can typically supply a heat pump only if the home has no electric shower, no electric cooker, and no other high-demand appliance running simultaneously (Energy Networks Association, 2026). For most UK homes, that is not realistic.
You can check yourself in two minutes. Look at the main fuse label on your fuse box or electricity meter, it will say “60A”, “80A”, or “100A”. Then count the number of occupied ways (circuit positions) in your consumer unit. If all ways are filled, or if the fuse is 60 amps or less, you almost certainly need an upgrade.
The rule of thumb from MCS Installer Standard MIS 3005 (2026) is that any home built before 2000 has a high probability of needing an electrical upgrade for a heat pump (MCS, 2026). Homes built after 2010 are more likely to have an 80-amp or 100-amp supply and a consumer unit with spare ways, but a check is still recommended.
How to verify your electrical upgrade installer is certified for heat pump work
Not all electricians are qualified to sign off on the electrical work for a heat pump. The only certifications that matter for the electrical side are NICEIC or NAPIT registration. For the heat pump installation itself, you need an MCS-certified installer.
A standard domestic electrician may be able to replace a consumer unit, but they must be registered with a competent person scheme such as NICEIC or NAPIT to self-certify compliance with Part P of the Building Regulations. Without that registration, the work must be notified to the local building control authority, which adds delay and cost (GOV.UK, Building Regulations: Part P, 2026).
To check a contractor’s NICEIC registration, use the “Find a Contractor” directory on the NICEIC website (NICEIC, 2026). For NAPIT, use their similar online register. For the heat pump installer, check the MCS Installers database (MCS, 2026).
If the same company is doing both the electrical upgrade and the heat pump installation, confirm that they hold both NICEIC (or NAPIT) and MCS certification. Many heat pump installers subcontract the electrical work, so you need to verify the subcontractor’s credentials separately.
The Boiler Upgrade Scheme grant covers the heat pump but not the electrical upgrade, here is what you actually pay
The Boiler Upgrade Scheme (BUS) in 2026 provides a fixed grant of £7,500 off the cost of an air source heat pump installation, or £7,500 for a ground source heat pump. However, the BUS grant explicitly excludes electrical supply upgrades, including any work on the main fuse, service head, consumer unit, or mains cable (DESNZ, Boiler Upgrade Scheme: Grant Conditions, 2026).
The typical split is that the BUS covers the heat pump unit, the indoor hot water cylinder, the basic refrigerant pipework, and the commissioning. The homeowner pays separately for any mains or consumer unit electrical work.
Some installers include a basic electrical upgrade, such as adding a dedicated circuit breaker to an existing consumer unit with a spare way, in their quoted price. Others do not, and you only discover the electrical cost when the MCS installer’s electrician arrives on site. To avoid surprises, ask for a written breakdown before accepting any quote: “Is the electrical upgrade included in the £X,XXX price, or is it an extra?”
Your true out-of-pocket cost after BUS is: heat pump installation cost (excluding grant) + electrical upgrade cost − £7,500. For example, a £12,000 heat pump installation with a £1,200 consumer unit upgrade costs £12,000 + £1,200 − £7,500 = £5,700.
Ofgem’s BUS eligible costs guidance (2026) confirms that any work on the electrical supply side of the heat pump’s isolator switch is not covered (Ofgem, BUS: Eligible Costs, 2026). Boiler Upgrade Scheme 2026: What’s Covered and What’s Not
How long a heat pump electrical upgrade takes and what it involves for your home
The timeline depends on the scope of work. A consumer unit swap takes 2 to 4 hours. A service head upgrade (fuse increase) takes 2 to 4 hours, but requires the DNO to attend, which can add a scheduling delay of several weeks. A full mains cable upgrade from the street to the consumer unit takes 4 to 8 hours, plus the time needed to dig a trench or drill through walls.
The process for a consumer unit upgrade is: the electrician isolates the power, removes the old fuse box, installs a new consumer unit with the heat pump’s dedicated circuit breaker, reconnects all existing circuits, tests earthing and bonding, and then restores power. For a service head upgrade, the DNO replaces the fuse holder and potentially the meter tails.
As a homeowner, you will experience a half-day power cut, typically from 8am to 1pm. You will need to reset all clocks, timers, and any appliances that lost programming. If the work involves a full mains cable upgrade, expect additional disruption: the electrician may need to lift floorboards, drill through an external wall, or dig up a garden path or driveway to lay new cable from the street to the consumer unit.
According to the Energy Saving Trust’s homeowner guide, most electrical upgrades for heat pumps are completed within a single working day (EST, Heat Pump Installation: A Homeowner’s Guide, 2026). The main variable is the DNO appointment for a service head upgrade, which can take 2 to 6 weeks to schedule.
Frequently Asked Questions
Yes, if your home was built before 2000 or has an older consumer unit. The Energy Saving Trust confirms most homes need at least a consumer unit upgrade to add a dedicated heat pump circuit.
Between £800 and £4,500. A simple consumer unit swap costs £800–£1,200, while a full mains cable replacement from the street can reach £4,500, according to the Energy Saving Trust's 2026 report.
An NICEIC-registered electrician must do the work to comply with Part P of the Building Regulations. The heat pump installer (MCS-certified) typically subcontracts this separately.
Most heat pumps require an 80 to 100 amp supply. The Distribution Network Operator (DNO) may need to upgrade your main fuse from 60 amps if your existing supply is insufficient.
No, it is usually quoted separately. The Energy Saving Trust states the average total installation cost of £12,000–£15,000 includes both the heat pump unit and electrical work.
