New-Build EV Charger and Heat Pump Load Management UK 2025: Complete Guide
Most new-builds now include heat pumps, induction hobs, and EV readiness?but a 60?80A supply can be stretched fast. This guide shows how to install a 7kW charger alongside a heat pump without nuisance trips or long DNO delays, using dynamic load management, smart tariffs, and solar/battery options. UK costs, wiring, and compliance included.
Why New-Builds Need a Load Plan
- Heat pumps draw 3?5kW plus defrost peaks; EV chargers add 7kW.
- Compact consumer units often have few spare ways; SPD now required.
- DNO fuse upgrades can take 4?12 weeks; dynamic load control often avoids upgrades.
Quick Spec Checklist
- Charger: 7kW smart, OZEV-approved, tethered for convenience.
- Protection: RCBO + SPD per BS 7671 Amd.2; PME/open-PEN protection if required.
- Load management: dynamic CT clamp on main tails.
- Cable: 6mm? T&E for short runs; upsize for 15m+ external runs.
- Evidence: photos of CU, main fuse rating, heat pump breaker, distance to charger.
Step-by-Step Plan
- Assess supply: note main fuse (60/80/100A), meter tails, and heat pump rating.
- Pick load management: dynamic CT (Ohme, Hypervolt, Wallbox Power Boost, Zappi + Harvi). Set headroom (e.g., 55A on 60A supply).
- Space and SPD: need RCBO + SPD way; if CU full, add small EV sub-board with SPD.
- Cable route: shortest safe path; external conduit if CU far from driveway/garage.
- DNO notification: G98 for 7kW; apply early if heat pump already present; fuse upgrade only if required.
- Commission: test RCD/RCBO, CT calibration, PME test if built-in, and live load test with heat pump running.
- Tariff setup: switch to smart tariff after stable commissioning; verify schedules.
Load Management Options (UK)
- Zappi + Harvi: dynamic, solar-friendly, great for headroom limits.
- Ohme Home Pro: CT-based load balance; strong Octopus/OVO integrations.
- Wallbox Pulsar Max + Power Boost: compact for meter cupboards; dynamic clamp.
- Hypervolt Home 3: clear load display, good app.
- Indra Smart PRO: robust load control, suited to multi-load homes.
Practical Scenarios
- 60A supply, 5kW heat pump: dynamic cap 55A; EV throttles during defrost; no trips.
- 80A supply, planning second EV: dual CT for load share; consider sub-board; future-proof with tethered 7m cable.
- Solar + battery: use Zappi ECO+/Ohme solar mode; keep battery reserve 20?30% for morning heating; divert midday solar to EV.
Costs (Typical 2025)
- Standard 7kW with load management: ?900??1,300.
- Add sub-board with SPD: +?250??450.
- Long run 15?25m conduit: +?200??400.
- DNO fuse upgrade (if needed): ?0??120, 2?8 weeks typical.
- Combined heat pump + EV commissioning visit: ?120??200.
Avoid These Mistakes
- Installing a dumb charger to save ?150?loses ?300??600/year in smart tariff savings.
- No dynamic load management on 60A with heat pump?expect trips or DNO pushback.
- Overfilling main CU; use a tidy sub-board.
- Ignoring WiFi at driveway; smart/load control fails without stable signal.
- Skipping SPD; surge damage voids warranties.
Smart Tariffs and Coordination
- Octopus Intelligent Go (~7.5p/kWh, 6 hours) works with Ohme, Wallbox, Zappi, Hypervolt.
- OVO Charge Anytime (~7p/kWh credit) with Ohme/compatible cars.
- Stagger loads: run DHW cycle outside EV window; set load cap so EV throttles automatically when heat pump peaks.
Solar and Battery Integration
- Daytime: prioritise DHW/space heating; divert surplus to EV via ECO+/solar modes.
- Battery: set reserve so battery does not empty into EV overnight; keep 20?30% for morning heating.
- SEG vs self-consume: in summer, solar-to-EV usually beats export rates.
Commissioning Checklist
- RCBO/SPD installed and tested; readings recorded.
- CT clamp orientation correct; headroom set to fuse.
- Charger WiFi/4G verified at install point.
- DNO notification submitted; reference stored.
- Customer shown override, schedule, and load limit settings; manual provided.
Real UK Example
- Oxfordshire new-build, 60A fuse, 5kW heat pump, Wallbox Pulsar Max + Power Boost. Added sub-board with SPD. Load cap 55A. DNO notified. No trips through winter; off-peak charging saves ~?420/year vs standard tariff.
Internal Links
- Load balancing fundamentals: /post/ev-charger-load-balancing-complete-guide-2025
- Heat pump + EV capacity: /post/heat-pump-and-ev-charger-electrical-capacity-guide-2025
- Tariffs: /post/smart-ev-tariff-optimization-complete-uk-guide-2025
- Solar integration: /post/ev-charger-solar-panel-integration-guide-uk-2025
Mini FAQ
Do I need DNO approval for 7kW with a heat pump?
Notify under G98. If supply is heavily loaded, DNO may ask for load management proof or upgrade.
Will load management slow charging a lot?
Only during high house load; it returns to 7kW when headroom is free.
Should I get 22kW three-phase?
Only if you have or plan three-phase and cars that support it. Most UK homes are single-phase; 7kW with good load control is sufficient.
What if WiFi is weak at the driveway?
Use 2.4GHz, add an outdoor extender, or run Ethernet/powerline to garage. Smart/load control needs stable comms.
Can I DIY the CT clamp?
No. Part P applies. Have a competent person fit and test; wrong orientation gives false load readings.
Survey Photo Checklist
- Consumer unit close-up showing spare ways and labels.
- Main fuse rating and meter tails.
- Heat pump breaker rating and location.
- Proposed charger wall with tape measure for height.
- Route from CU to charger (indoors/outdoors) with any obstacles.
- WiFi signal test screenshot at driveway/garage.
Heat Pump Behaviour to Plan Around
- Defrost cycles can spike draw briefly; dynamic load management should account for this headroom.
- Schedule DHW away from EV off-peak window if using smart tariffs.
- Set load cap slightly below fuse to avoid nuisance trips during defrost.
DNO Interaction Tips
- Submit G98 with notes on dynamic load management and CT clamp settings.
- If DNO asks for evidence, provide installer letter, photos of CT, and load cap setting.
- For fuse upgrades, book early; many DNOs do 80?100A swaps free if tails and CU are suitable.
Sub-Board vs Main CU
- Sub-board: adds RCBO + SPD cleanly when main CU is full; keeps EV circuit tidy.
- Main CU spare ways: fine if space exists and SPD can be accommodated; avoid overcrowding.
- Meter cupboard installs: ensure IP rating and ventilation; avoid cramming devices that overheat.
Additional Real-World Example
- Newcastle new-build flat with allocated bay: Hypervolt Home 3, dynamic cap 50A on 60A fuse, sub-board with SPD, WiFi extender fitted. No trips; Octopus Intelligent saves ~?380/year; heat pump runs outside EV window.
More FAQ
Should I pre-wire during construction?
Yes?run suitably sized cable/conduit and CT path; cheaper and neater than retrofits.
Can I use a commando socket instead?
Not recommended for long-term home use; a fixed smart charger with load management is safer and compliant.
Do I need ventilation for the charger?
Most wallboxes are fine outdoors (IP rated). Ensure glands sealed and no direct spray from gutters.
What about battery + heat pump + EV together?
Use hierarchy: keep battery reserve, let heat pump run first, then divert surplus to EV. Dynamic load keeps total under fuse.
Cost Scenarios (Illustrative)
- Basic 7kW + load management, short run: ?950??1,200.
- With sub-board + SPD + 20m external conduit: ?1,300??1,750.
- With WiFi extender, tariff setup, and combined heat pump/EV test: add ?80??150.
- Fuse upgrade (if required): often free to ?120; schedule 2?8 weeks.
Install Day Checklist
- Verify RCBO type A/F, SPD fitted, terminations torqued.
- CT clamp orientation correct; headroom set below fuse rating.
- Charger height ~1,200?1,400mm; cable reach confirmed for bay.
- WiFi signal tested at charger; extender installed if weak.
- App configured: override button works; schedules off until tested.
- DNO notification submitted; reference recorded on circuit schedule.
Car and API Considerations
- Some car APIs can conflict with charger schedules; start with charger-controlled schedules only.
- If using Octopus Intelligent via car API (e.g., Tesla), ensure charger is in ?dumb? mode during initial setup.
- Verify car charge limit and start/stop times after linking to avoid double scheduling.
Common Pitfalls (And Fixes)
- Problem: Heat pump and EV both start at 23:00 causing trips.
Fix: Stagger DHW/space heating earlier; set load cap to throttle EV during peaks. - Problem: CT clamp installed backwards.
Fix: Electrician to correct orientation; re-test headroom. - Problem: WiFi dropouts killing smart sessions.
Fix: Use dedicated 2.4GHz SSID or outdoor AP; in rural areas, consider 4G backup module if supported.
Extra Case Study
- Surrey townhouse, 80A supply, 7kW charger, 8kW heat pump, battery storage. Load cap set to 70A; battery reserve 30% overnight. EV charges off-peak; battery serves heat pump morning peak. Bills down ~?55/month vs pre-optimisation.
Extended FAQ
Will a battery stop the EV and heat pump clashing?
It can reduce grid draw but still set dynamic load management; do not rely solely on the battery to prevent overload.
Do I need a dedicated supply for the charger in a new-build?
Yes?a dedicated circuit with appropriate breaker/RCBO and SPD. Do not share with other loads.
Can I install outside a garage on a timber frame?
Yes if using correct fixings and fire-stopping where cable penetrates; maintain IP rating and mechanical protection.
What if I plan a second EV later?
Choose a charger supporting load sharing or a dual setup; run conduit sized for future cable if trenching now.
How often should load settings be reviewed?
Review annually or after adding new loads (battery, additional heat pump, induction upgrade). Re-test headroom after DNO fuse changes.
