How to Determine the Right Circuit Size for Your EV Charger
As electric vehicles (EVs) become more popular, many homeowners are eager to install Level 2 chargers in their homes. One of the most common questions I hear is:
"Can I install a 50A Level 2 charger at home?"
The answer isn't always a simple yes or no—it depends on your main electrical panel capacity and existing electrical load. As a former C10 licensed electrician, I’ve seen many homeowners assume that just because a charger requires a 50A breaker, they can install one without considering the panel’s total capacity. Let's break down how to determine the right circuit size for your EV charger.
Step 1: Understand Your EV Charger’s Requirements
Level 2 chargers operate on a 240V circuit and require a dedicated breaker. The most common sizes include:
16A charger → Requires a 20A breaker
24A charger → Requires a 30A breaker
32A charger → Requires a 40A breaker
40A charger → Requires a 50A breaker(Most Common)
48A charger → Requires a 60A breaker
Per NEC (National Electrical Code) 80% rule, the breaker size should be 125% of the charger’s continuous load to prevent overheating and ensure safe operation.
Step 2: Check Your Main Panel Size
Your home’s main panel has a total ampacity (typically 100A, 125A, 150A, or 200A). The key question is:
"Do you have enough capacity left to support an EV charger?"
To check this:
Look at your panel’s main breaker rating (e.g., 100A, 200A).
Add up the major loads in your home, including:
HVAC system
Electric range/oven
Water heater
Dryer
Pool equipment
Existing circuits
Compare the total usage to your panel’s max capacity.
If your panel is already heavily loaded, adding a 50A charger could overload the system. In that case, you may need a panel upgrade or load management system to safely install the charger.
Step 3: Load Calculation & Permitting
Before installing an EV charger, a load calculation should be performed per NEC Article 220. This ensures that your electrical panel can handle the added demand. Some jurisdictions require this calculation when pulling a permit for installation.
If your panel can’t support a high-amperage charger, alternatives include:
Installing a lower-amp charger (e.g., 24A instead of 40A)
Upgrading your panel to 200A or more
Using a load-sharing device to manage energy distribution
Final Thoughts
Installing an EV charger isn’t just about plugging in a 50A breaker—it requires understanding your home’s electrical capacity. If you’re unsure, consult a licensed electrician who can evaluate your panel and help you choose the safest and most efficient option.
Need help determining your EV charger circuit size? Feel free to reach out us or contact an experienced electrician for a proper assessment.
