Heat pumps draw electricity differently to gas boilers. They run steadily for long periods and can have short peaks for defrost or an immersion boost. That means the supply, protection and controls must be right from day one.
Getting the electrics right delivers safety, reliability and efficiency. It reduces nuisance tripping, supports lower running costs and keeps warranties valid. Clima Tech assesses your home, upgrades where needed, certifies to NICEIC and BS 7671, and coordinates with your DNO if a main fuse change is required. With 20+ years’ experience and MCS, REFCOM, NICEIC and Gas Safe accreditations, you’re in safe hands. New to heat pumps? Start with what is an air source heat pump.
Understanding Loads: Amps, Diversity And Your Home
Typical running currents vary by model and size. An air source heat pump compressor often draws around 6–18 A in heating, with brief peaks a little higher. Circulation pumps are small (0.2–1 A each). A 3 kW immersion heater is about 13 A and may run for hot water boosts or legionella cycles. Ground source units can be similar or a touch higher on start-up; modern inverters reduce inrush.
Diversity (ADMD) recognises that not everything runs at once. We add realistic loads for the heat pump and high‑draw appliances so the total stays within safe limits. EV chargers (16–32 A), electric showers (30–45 A), induction hobs and hot tubs can tip the balance and may drive the need for upgrades. Read more in do air source heat pumps use a lot of electricity.
kW vs Amps And Supply Types
Amps (A) are current; kW is power. On a 230 V supply, 2 kW is roughly 9 A (2,000 ÷ 230). Most UK homes are single‑phase; larger properties may have three‑phase, which spreads load across phases and increases capacity.
Our Load Assessment Process
We start with simple checks: recent bills, supply rating, meter tails, earthing and bonding, consumer unit space and device types, plus a suitable outdoor isolator position. On site we verify protective devices, cable routes and any constraints.
If usage is unclear, we can fit a non‑invasive data logger for 7–14 days to capture real peaks. We then give a clear outcome: proceed as‑is; minor works (e.g., a dedicated circuit); or DNO involvement for a main fuse/service head upgrade. See our electrical installation services for more detail.
- What to prepare: photos of your consumer unit and meter
- Confirm where your main earth and bonding are
- List of high‑load appliances and when you use them
Main Fuse And DNO Approvals: What To Expect
Many older homes still have 60 A main fuses. If your calculated demand needs more headroom, we’ll recommend an uprate to 80 A or 100 A. The DNO owns the service head and cut‑out; the supplier handles the meter; the homeowner owns the consumer unit and internal wiring.
For low‑carbon tech, we follow the DNO’s Connect & Notify or Apply to Connect process. Approvals often take 10–20 working days. Fuse upgrades can take 2–8 weeks depending on the DNO and whether the service cable needs attention. On the day, power is briefly off while the engineer fits an isolator and upgrades meter tails if needed.
Consumer Unit Upgrades And Protection
Your heat pump should have a dedicated circuit with correctly sized MCB or RCBO. Inverter‑driven units require RCD Type A (or Type F if specified by the manufacturer). This avoids nuisance trips and ensures proper protection.
We add surge protection devices (SPD) to protect electronics, label circuits clearly, and fit a weatherproof external isolator near the outdoor unit for safe maintenance. All works comply with BS 7671 (18th Edition), include Part P notification where applicable, and we verify bonding to water and gas for safety.
NICEIC-Compliant Works And Your Documentation
After works you receive an Electrical Installation Certificate or Minor Works Certificate, with test results. Where relevant, we notify building control under Part P and provide you with confirmation.
Electrical compliance supports MCS commissioning and BUS grant eligibility. We include a handover pack covering product literature and settings. The DNO manages supply equipment; the meter operator handles the meter; we handle everything else and coordinate so nothing is missed. Learn about grants via the boiler upgrade scheme.
Realistic Timelines From Survey To Switch‑On
Fast track (no upgrades): survey and design in week 1; installation scheduled for week 2–3; commissioning and handover the same or next day. Power may be off for up to an hour during electrical works.
With a DNO fuse upgrade: survey and application in week 1; approval in 2–4 weeks; DNO visit scheduled while we prepare; install follows within days. Overall allow 4–10 weeks, driven by DNO lead times. For the full journey, see the heat pump installation journey.
This image was generated with AI and may not always represent the product or service exactly.
Costs, Value And Finance Options
Indicative ranges (every home differs): dedicated circuit £250–£600; SPD £80–£200; external isolator £60–£150; consumer unit upgrade £500–£1,200. DNO fuse uprates are often free, but not guaranteed; reinforcement works may carry a cost.
Good electrics pay back over the system’s life: safer operation, fewer trips, efficient running, smoother servicing and stronger resale value. We provide itemised quotes with clear scope, so you know exactly what’s included.
Case Studies: Three Common Homes And Outcomes
1930s semi, 60 A fuse + EV charger: load assessment showed limited headroom. DNO uprated to 100 A; we installed a dedicated RCBO heat pump circuit and SPD. Total time: six weeks end‑to‑end. Result: stable operation with EV charging managed on a schedule.
New‑build with spare capacity: single dedicated circuit and external isolator fitted in half a day. Minimal disruption. Result: quiet, efficient heating with no nuisance tripping.
Rural property with long service cable: DNO assessed the supply; full upgrade was costly. We implemented selective load management and scheduling to avoid peaks. Result: reliable heating without major network works.
Future‑Proofing: Solar, EV And Indoor Comfort
We can plan spare capacity for future EV charging or induction cooking, and stage upgrades to spread cost. If helpful, we add load management so high‑draw devices don’t overlap.
Solar PV pairs well with heat pumps and hot water. Add a diverter and a well‑sized cylinder to harvest daytime solar. To explore sizing, see how many solar panels are needed to power a typical house. For comfort, MVHR and efficient AC complement low‑temperature heating and improve air quality.
FAQs: Electrical Upgrades For Heat Pumps
You might not need a full rewire. Many homes only need a dedicated circuit or RCD/RCBO changes. We’ll advise after a simple assessment and only recommend what’s necessary.
Fuse upgrades are often free where capacity exists, but it’s set by the DNO. If cable reinforcement is required, the DNO may quote for works. We handle the application for you.
Power is typically off for 30–90 minutes during electrical works or a DNO visit. We schedule at convenient times and keep disruption to a minimum.
Nuisance tripping is rare when protection is correctly selected and circuits are designed for inverter equipment. Type A or F RCDs and proper cable sizing are key.
Routine checks are simple: visual inspection of isolators and labels, and testing at service intervals. Annual heat pump servicing is a good time to verify electrics.
Next Steps: Book Your Electrical Survey With Clima Tech
Send us photos of your consumer unit, meter and main bonding points, plus a list of high‑load appliances. We’ll confirm capacity and outline any upgrades in plain English.
Clima Tech delivers punctual surveys, clear recommendations and tidy, NICEIC‑certified installations, backed by MCS, REFCOM, NICEIC and Gas Safe. Ready to get started? Contact our friendly team today.
FAQs
Do I Need Three‑Phase For A Heat Pump?
Most UK homes do not. Single‑phase supplies are fine for typical domestic heat pumps. We’ll confirm during the load assessment.
Will A Heat Pump Trip My Electrics?
Not when designed correctly. A dedicated circuit with the right RCD/RCBO and cable sizes prevents nuisance tripping.
What If I Have A 60 A Main Fuse?
We apply to the DNO to uprate to 80 A or 100 A if calculations show it’s needed. Many upgrades are straightforward.
How Long Does DNO Approval Take?
Allow 10–20 working days for approval and 2–8 weeks for an upgrade visit, depending on your DNO’s schedule.
Do I Need An Electrical Certificate?
Yes. You’ll receive an EIC or Minor Works Certificate and Part P notification where required, all under NICEIC.
Can You Coordinate With My EV Charger?
Yes. We account for EV load and can add load management so charging and heating don’t clash.
Who Handles Grants Paperwork?
We provide the electrical compliance needed for MCS and BUS applications and guide you through next steps.