The right amperage for a car charger (EVSE) depends primarily on your home's electrical capacity and your daily driving needs. For most homeowners, a 50-amp circuit allowing for a 40-amp charger is the ideal balance of charging speed and installation cost.
Choosing an amperage is about matching the charger's power draw to your electrical system's limits. The charger's amperage must not exceed 80% of the circuit breaker's rating—a key National Electrical Code (NEC) safety rule. This means a charger rated at 40 amps requires a dedicated 50-amp circuit breaker.
The table below compares common home charging options, showing how amperage directly translates to charging speed for a typical EV with a 75-kWh battery.
| Circuit Breaker Size (Amps) | EVSE Max Amperage (80% Rule) | Power Level (kW) | Approx. Miles Added Per Hour* | Time for Full Charge (0-100%) |
|---|
| 15 Amp (Standard Outlet) | 12 Amps | 1.4 kW | 3-5 miles | ~50+ hours |
| 20 Amp | 16 Amps | 3.8 kW | 12-15 miles | ~20 hours |
| 30 Amp | 24 Amps | 5.8 kW | 18-22 miles | ~13 hours |
| 40 Amp | 32 Amps | 7.7 kW | 25-30 miles | ~10 hours |
| 50 Amp | 40 Amps | 9.6 kW | 30-35 miles | ~8 hours |
| 60 Amp | 48 Amps | 11.5 kW | 35-40 miles | ~6.5 hours |
*Approximate range based on an efficiency of 3-4 miles per kWh.
A standard 120-volt household outlet (Level 1 charging) is very slow, often called a "trickle charge." It's best as a backup. For daily use, a 240-volt Level 2 charger is highly recommended. The 40-amp charger on a 50-amp circuit is the most popular choice because it provides a full charge overnight without requiring the most expensive electrical panel upgrade. If your daily commute is short, a 20-amp or 30-amp circuit might suffice. For EVs with larger batteries or if you frequently return home with a low charge, consider a 48-amp charger on a 60-amp circuit for maximum speed. Always consult a licensed electrician to assess your home's wiring and panel capacity before installation.
