One of the most common questions about EV charger installation is whether your home's electrical supply can handle it. Here's a complete guide to main fuses, supply capacity, and when you might need an upgrade.
Understanding Your Main Fuse
What Is the Main Fuse?
The main fuse (or service fuse) is the first protection device in your electrical system. It:
Common Main Fuse Sizes
| Fuse Size | Typical Property | Max Continuous Load |
|---|---|---|
| 60A | Older/smaller properties | ~14kW |
| 80A | Standard modern homes | ~18kW |
| 100A | Larger modern homes | ~23kW |
Note: The "Max Continuous Load" is approximate. The safe continuous load is typically 80% of the fuse rating to prevent nuisance tripping.
How to Check Your Fuse Size
Option 1: Look at the fuse
Option 2: Check your DNO records
Option 3: Ask your electrician
Do You Need an Upgrade?
The Calculation
Step 1: Determine your current peak load
Typical household loads:
| Appliance | Power Draw |
|---|---|
| Electric shower | 7–10kW |
| Electric oven | 2–3kW |
| Electric hob | 3–7kW |
| Kettle | 2–3kW |
| Washing machine | 0.5–2kW |
| Tumble dryer | 2–3kW |
| Immersion heater | 3kW |
| Lighting | 0.5–1kW |
| General (fridge, TV, etc.) | 0.5–1kW |
Worst-case scenario: If someone takes an electric shower (9kW) while the oven is on (3kW) and the kettle boils (3kW), you're already at 15kW.
Step 2: Add your EV charger
| Charger Rating | Power Draw |
|---|---|
| 3.6kW (16A single phase) | 3.6kW |
| 7kW (32A single phase) | 7kW |
| 22kW (three phase) | 7kW per phase |
Step 3: Compare to your supply
| Main Fuse | Safe Continuous (80%) | With 7kW Charger |
|---|---|---|
| 60A | ~14kW | Tight if other heavy loads |
| 80A | ~18kW | Usually fine |
| 100A | ~23kW | Plenty of headroom |
The 60A Question
Do I definitely need an upgrade from 60A?
Not necessarily. Here's why:
Smart chargers with load management:
Charging timing:
Real-world usage:
When Upgrade Is Likely Needed
60A supply + any of these = likely upgrade needed:
60A supply + these factors = probably fine:
The Upgrade Process
Who Does the Upgrade?
DNO (Distribution Network Operator):
Your electrician:
How to Request an Upgrade
Finding Your DNO
| Region | DNO |
|---|---|
| South & East England | UK Power Networks |
| North West England | Electricity North West |
| North East & Yorkshire | Northern Powergrid |
| Midlands | Western Power Distribution |
| South West & Wales | Western Power Distribution |
| Scotland (south) | SP Energy Networks |
| Scotland (north) | Scottish & Southern Electricity |
| Northern Ireland | NIE Networks |
Upgrade Costs
Good news: Many fuse upgrades are free.
| Situation | Typical Cost |
|---|---|
| 60A to 80A (fuse only, cable adequate) | Often free |
| 60A to 100A (fuse only, cable adequate) | Often free |
| Fuse + service cable upgrade | £500–2,000+ |
| Fuse + significant cable work | £2,000–5,000+ |
Why free? If your existing service cable can handle the higher rating, the DNO just swaps the fuse. They're generally supportive of EV charging and often don't charge for simple fuse upgrades.
When it costs money: If the cable from the street to your property is too small for higher capacity, it needs replacing. This involves digging, new cable, and significant work.
Timeline
| Stage | Typical Time |
|---|---|
| Application and assessment | 1–4 weeks |
| Simple fuse upgrade | 2–4 weeks |
| Cable upgrade required | 6–12 weeks |
| Complex situations | 3–6 months |
Impact on charger installation: If an upgrade is needed, your installer may:
Alternatives to Upgrading
Smart Charger with Load Management
How it works:
Benefit: Can make a 7kW charger work on a 60A supply without upgrade.
Cost: Smart chargers with load management cost £50–150 more than basic models.
Recommended products:
Lower Power Charger
If you have a constrained supply, consider:
| Charger Rating | Daily Charge (8 hours overnight) |
|---|---|
| 3.6kW | ~28kWh (80–100 miles) |
| 7kW | ~56kWh (150–200 miles) |
For most daily commutes, even 3.6kW overnight provides plenty of range. A 7kW charger is nice but not essential.
Three-Phase Supply
For larger homes or 22kW charging:
Cost: Installing three-phase where it doesn't exist can cost £3,000–10,000+. Usually only worthwhile if you have other high-power needs (workshop, commercial use, heat pump).
What Installers Check
During the Survey
A reputable installer will:
Red Flags
Be cautious if an installer:
Common Questions
"Can I just ignore the fuse rating?"
No. If you regularly exceed your fuse rating:
"Will my installer handle the DNO application?"
Usually yes. Most installers will:
"What if my supply can't be upgraded?"
Rare but possible scenarios:
Solutions:
"Does the upgrade affect my electricity bill?"
No. A larger fuse doesn't mean higher standing charges or costs. You only pay for what you use.
Summary
| Main Fuse | 7kW Charger Feasibility | Recommendation |
|---|---|---|
| 60A | Possible with care | Use smart charger with load management |
| 80A | Usually fine | Standard installation |
| 100A | Plenty of headroom | Standard installation |
Decision Guide
60A supply:
80A or 100A supply:
Standard 7kW installation should be straightforward. No upgrade typically needed unless you have exceptional loads.
Key takeaway: Many homes with 60A supplies can run a 7kW EV charger without upgrade, especially with modern smart chargers. But always get a professional assessment — assumptions about electrical capacity can be dangerous.