Introduction to EV Charging Wire Requirements
Electric vehicle charging stations require proper wire sizing to ensure safe, efficient operation and compliance with NEC Article 625. Unlike typical appliances, EV chargers operate as continuous loads, requiring special consideration in circuit design.
Understanding EV Charging Levels
Different charging levels have different wire requirements:
- Level 1 (120V): 12-16 amps, 14-12 AWG wire
- Level 2 (240V): 16-80 amps, wire size varies
- Charging Speed: Level 2 provides 12-60 miles of range per hour
- Most home installations use 32-48A chargers
NEC Article 625 Requirements
EV charging is considered a continuous load. NEC requires:
- Circuit Rating = Charger Amperage × 125%
- Dedicated circuit required, no other loads allowed
- GFCI protection required for certain installations
Wire Size Selection
Select wire based on charger amperage with continuous load factor applied.
Example Calculation
A 32A charger requires 32A × 1.25 = 40A circuit. Use 8 AWG copper wire with a 40A breaker.
Common Installation Scenarios
Wire sizing depends on distance and installation location:
- Garage Installation (20-30 ft): 8 AWG for 32A charger
- Driveway Installation (100 ft): May need 6 AWG for voltage drop
- Long runs require upsizing wire gauge
- Always verify voltage drop under 3%
Best Practices
Follow these guidelines for successful EV charger installations.
Important Warning
Never use extension cords with EV chargers. Always install a dedicated circuit to the charging location. Consult a licensed electrician for installation.
Conclusion
Proper wire sizing for EV charging stations is critical for safe, efficient, and code-compliant operation. By following NEC Article 625 requirements, applying the 125% continuous load factor, and accounting for voltage drop on long runs, you can ensure your EV charging installation will provide years of reliable service.
Use our Wire Gauge Calculator to determine correct wire size for your EV charger.