What Cable Size Do I Need for a 7kW EV Charger at Home?

A Complete Guide to Safe EV Charger Wiring and Voltage Drop Prevention (230V EU Standard)

Installing a 7kW EV charger at home in Europe? Using the correct cable size is essential to ensure safety, prevent overheating, and maintain efficient charging.

⚡ Power Basics: How Much Current Does a 7kW EV Charger Draw?

Most residential EV chargers in the UK and EU operate on single-phase 230V AC.

Using Ohm’s Law:

Current = Power ÷ Voltage
7,000 W ÷ 230 V = 30.4 A

➡️ Round up to 32 A for safety and buffer.

So your cable and circuit must handle at least 32 amps continuously.

🧰 Recommended Copper Cable Size for 7kW Chargers

Following IEC and EU electrical standards, here’s what’s commonly recommended:

Always use multi-core copper cable, rated for fixed installation (e.g., NYY or H07RN-F).

📏 Long Cable Runs? Voltage Drop Still Applies

Even with 230V, long cable runs can cause voltage drop, which reduces efficiency and can trigger faults.

🔍 Voltage Drop Formula (Updated for 230V):

Voltage Drop (V) = 2 × Current × Length × Resistivity ÷ Area

• Current = 32 A

• Copper resistivity = 0.0172 Ω·mm²/m

• Area = cable cross-section in mm²

💡 Example:

65 meters, 6 mm² copper, 32 A:

Vdrop = 2 × 32 × 65 × 0.0172 ÷ 6 = ≈ 11.9 V

11.9V ÷ 230V ≈ 5.2% drop, which exceeds the recommended 5% limit.

➡️ In this case, upgrade to 10 mm² copper.

✅ Cable Size Recommendations (Quick Guide for 230V Europe)

🚨 EU Installation Safety Tips

• Use a dedicated 40A MCB or RCBO with Type A or B protection

• Ensure cable complies with IEC 60364 and local wiring regulations

• Avoid aluminum cables — only use copper for EVSE

• Hire a certified electrician familiar with EV charger installations

💡 Final Thoughts

Choosing the right cable for your 230V 7kW home EV charger ensures:

• Safe, stable charging

• Reduced energy loss

• Compliance with EU electrical codes

✅ For up to 30m: 6 mm² is fine
✅ For longer runs: Go with 10 mm²