What Size Cable Do You Need for an EV Charger?
For a 7.4kW single-phase EV charger (32A), use 6mm² cable on a dedicated 32A Type A RCBO circuit (BS 7671). For runs over 25m, upgrade to 10mm² to manage voltage drop. Under NEC, EV charging is a continuous load — apply the 125% rule, requiring a 40A circuit with 8 AWG minimum.
Quick Reference: Cable Size for EV Charger by Standard
| Standard | Cable Size | Conditions | Reference |
|---|---|---|---|
| BS 7671 | 6mm² (7.4kW) or 10mm² (long runs) | Dedicated circuit, Type A RCBO | Table 4D1A, BS 7671 Section 722 |
| NEC | 6 AWG (50A) or 8 AWG (40A) | Continuous load (125% rule), NEC 625 | Table 310.16 |
| AS/NZS 3008 | 6mm² | Dedicated circuit, AS/NZS 3000 | Table 13 |
| IEC 60364 | 6mm² | Dedicated circuit per IEC 61851 | Table B.52.4 |
Values shown are for copper conductors in typical domestic/commercial conditions. Actual size depends on installation method, ambient temperature, and cable length. Use our free cable sizing calculator for your exact scenario.
Typical Applications for a EV Charger
- 7.4kW home wallbox
- 22kW three-phase charger
- 3.6kW granny charger
Calculate Your Exact Cable Size
These are general guidelines. Your specific installation needs exact calculation accounting for cable route length, installation method, ambient temperature, and cable grouping.
Frequently Asked Questions
Why does an EV charger need 6mm² cable?▼
A 7.4kW single-phase EV charger draws 32A continuously. While 4mm² is rated above 32A, EV charging is a continuous load (3+ hours) — 6mm² provides adequate margin for thermal safety and voltage drop.
What type of RCD for an EV charger?▼
BS 7671 Section 722 requires Type A RCD protection (minimum 30mA) for EV charging circuits. Many installers use a Type A RCBO. Some chargers have built-in DC fault detection, but external RCD is still required.
Can I install an EV charger on a 13A socket?▼
While possible with a granny charger (3.6kW, 16A), it is slow and not recommended for regular use. A dedicated 32A circuit with a proper wallbox is the safe and efficient solution.
What cable for a three-phase 22kW EV charger?▼
A 22kW three-phase charger draws 32A per phase. Use 4mm² 5-core SWA cable minimum, or 6mm² for runs over 20m. A 32A three-phase RCBO is required.
How long does it take to charge an EV on 7.4kW?▼
A typical 60kWh EV battery charges from 20% to 80% (36kWh) in approximately 5 hours on a 7.4kW charger. This makes overnight charging practical for daily commuting needs.
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