EV Charger Installation Voltage Drop Guide
Essential voltage drop considerations for Level 2 and DC fast EV charger installations. Covers circuit sizing, long runs, and NEC requirements for electric vehicle charging.
EV Charging: A Growing Challenge
Electric vehicle charging installations are becoming increasingly common in residential, commercial, and public settings. These circuits often present significant voltage drop challenges because chargers are frequently located far from the electrical panel—in garages, parking structures, or outdoor locations—while drawing substantial continuous current.
Proper voltage drop calculation is essential for EV charger installations to ensure full charging power delivery, meet NEC requirements, and avoid callbacks for underperforming systems. This guide covers the voltage drop considerations specific to electric vehicle supply equipment (EVSE).
EV Charger Types and Power Requirements
| Charger Type | Power | Voltage | Current |
|---|---|---|---|
| Level 1 (Cord-set) | 1.4-1.9 kW | 120V | 12-16A |
| Level 2 (Basic) | 3.8-7.7 kW | 240V | 16-32A |
| Level 2 (High Power) | 11.5-19.2 kW | 240V | 48-80A |
| DC Fast Charge | 50-350 kW | 480V 3Φ | 60-420A |
NEC Requirements for EVSE
NEC Article 625 governs electric vehicle charging installations. Key requirements affecting voltage drop calculations include:
- Continuous Load: EV charging is classified as a continuous load, requiring conductor sizing at 125% of the maximum current
- Voltage Drop: Standard NEC recommendations apply—3% for branch circuits, 5% total
- Overcurrent Protection: Must match the EVSE rating and conductor ampacity
Common Installation Scenarios
Residential Garage
- • 48A charger at 240V
- • 50-100 ft typical run
- • 6 AWG copper common
- • Verify 3% max drop
Commercial Parking
- • Multiple 32-80A stations
- • Long runs (100-300 ft)
- • Sub-panel often required
- • Load management systems
Size Your EV Charger Circuit
Use our voltage drop calculator to properly size your EV charger circuit. Enter your charger's current rating, circuit length, and see the recommended wire size for NEC-compliant installation.
EV Charger Calculator