Electric Vehicle Charger Circuit Breaker Selection Guide (USA – NEC)

Okay, you’ve got an electric vehicle (EV), and now it’s time to plug it in and charge it up. But here’s the challenge in real time—you can’t just plug your EV charger into any old outlet without considering one crucial piece of equipment: the circuit breaker.

So, making sure your circuit breaker is the right size and type for your EV charger is essential to avoid nasty surprises later on. 

Trust me, you don’t want to skip this step.

What is a Circuit Breaker?

So, let’s break it down real quick. A circuit breaker is a safety device that automatically stops the electrical current if something goes wrong—think of it as the hero of your charging system. 

If your EV charger pulls too much power (or if there’s a fault like a short circuit), the circuit breaker trips, and cuts off the current before anything bad happens. No power, no problem.

ChargePoint Home Flex Tripping Breaker: Solution

Why Is Selecting the Right Circuit Breaker Important for Your EV Charger?

For EV chargers, a circuit breaker is there to protect your car, your charger, and your home’s wiring system from overloads or electrical faults. 

Without the right one, you’re asking for trouble, so it’s important to choose wisely.

Circuit breakers are like the bouncers of your home’s electrical system. They regulate the flow of power (W or kW) and keep everything from overheating, catching fire, or damaging your home’s electrical system. 

Types of Circuit Breakers for EV Chargers

1. MCB (Miniature Circuit Breaker)

What is it?

• MCBs are small, compact breakers designed for low-power applications and residential use. They protect circuits from overload and short circuits.
  
• They are rated for current up to 100A, with Type C MCBs commonly used for residential Level 2 EV chargers.
  

Why is it used for EV Charging?

• MCBs are ideal for Level 2 chargers because they can handle the moderate inrush current typical of EV chargers. They also provide short-circuit protection and prevent damage due to overloads.
  
• Type C MCBs are best because they trip at 5-10 times the rated current, allowing for brief surges without tripping unnecessarily.

Where to use it?

• MCBs are primarily used in residential settings and for Level 2 EV chargers (240V) in homes. They are not suitable for high-amperage industrial or commercial applications.

2. MCCB (Molded Case Circuit Breaker)

What is it?

• MCCBs are larger and more robust than MCBs and are designed to handle higher currents (usually from 100A to 2500A). They offer adjustable trip settings for overload protection and short-circuit protection.
  

Why is it used for EV Charging?

• MCCBs are used in larger commercial and industrial EV charging stations that require more power capacity. For example, DC Fast Chargers (high-power chargers) need an MCCB to handle the high current demands and provide adjustable trip settings for greater flexibility.
  

Where to use it?

• MCCBs are best suited for high-power charging stations or for installations requiring customized settings, especially in commercial or industrial environments with DC fast chargers or high-power Level 2 chargers.
  

3. RCD (Residual Current Device) / GFCI (Ground Fault Circuit Interrupter)

What is it?

• RCDs (also known as GFCIs) detect leakage currents or faults to the ground and cut the power off to prevent electrical shocks or fire hazards. This is critical for any EV charger, especially when charging outdoors or in areas prone to moisture, like garages or parking lots.
  

Why is it used for EV Charging?

• An RCD/GFCI is essential when installing Level 2 chargers in outdoor or damp environments where moisture could pose a shock risk.
  
• It adds an extra layer of protection in case of electrical faults, ensuring that if any current leakage is detected, it shuts down the charging process immediately.
  

Where to use it?

• RCDs/GFCIs are mandatory in areas exposed to moisture, including outdoor charging stations or garages, and often come integrated with EV chargers in certain models for added safety.
  

4. AFCI (Arc Fault Circuit Interrupter)

What is it?

• AFCIs are circuit breakers designed to detect electrical arcs that could potentially cause fires due to faulty wiring or damaged insulation. They trip the circuit if they sense arcing faults that can lead to fire hazards.
  

Why is it used for EV Charging?

• AFCIs are highly recommended in older homes with outdated wiring systems. Since EV chargers will be in use for extended periods, an AFCI adds an extra layer of fire protection by cutting off power if an arc is detected.
  

Where to use it?

• AFCIs are ideal for older homes or areas where the electrical system might be older and prone to issues like faulty wiring. Some Level 2 chargers require or recommend AFCIs for extra fire protection.

How To Choose the Right Circuit Breaker for EV Charger?

Choosing the right circuit breaker isn’t just about picking one up at the hardware store and calling it a day. You need to think about:

1. Amperage Rating
   The amperage of the breaker needs to match the current your charger will pull. Too low? It trips all the time. Too high? You risk damaging your charger or electrical system.
   
   • Level 1 chargers typically require a 15-20 amp breaker.
     
   • Level 2 chargers need a 40-50 amp breaker.
     
   • DC Fast Chargers might need 100 amps or more.
     
2. Voltage Rating
   Make sure the breaker is rated for the voltage your charger uses—this is usually 120V for Level 1 and 240V for Level 2 chargers. Fast chargers use even higher voltages, so they need a beefier breaker.
   
3. Compliance with Codes
   You also need to make sure your breaker meets the National Electrical Code (NEC) and local regulations. Skipping this could lead to safety issues, or worse, void your insurance.

Choosing the right circuit breaker involves considering several factors, including:

1. Charger Rating:
   
   • The breaker needs to match the amperage of your EV charger. For instance, for a 7.4 kW charger, you would calculate the amperage requirement and pick a breaker rated accordingly.
     
2. Breaker Type:
   
   • MCB (Miniature Circuit Breaker): For residential installations.
     
   • RCD (Residual Current Device): For additional protection against earth leakage.
     
   • AFCI (Arc Fault Circuit Interrupter): For extra protection against arc faults, which can lead to fires.
     
3. Voltage Compatibility:
   
   • Ensure that the circuit breaker supports the voltage of the EV charger (usually 240V for Level 2 chargers).
     
4. NEC Compliance:
   
   • Follow the National Electrical Code (NEC) or local electrical codes for sizing and wiring. In most cases, NEC 625 applies for EV charging stations.
     
5. Safety Margins:
   
   • It’s crucial to choose a breaker that slightly exceeds the maximum current draw to prevent frequent tripping.

How to Choose the Right Ampere Rating for CB?

Alright, here’s where things get a little more specific. The amperage rating of your breaker needs to match your charger’s power needs. If you’re using a Level 1 charger (like a regular household outlet), a 15-20 amp breaker will usually do the trick.

If you’re upgrading to a Level 2 charger (which runs on 240 volts and charges your car faster), you’ll need a 40-50 amp breaker. 

Fast chargers, like those at public charging stations, require much more power—100 amps or more, depending on the charger’s output.

Here’s a quick reference table:

Charger Type	Voltage	Amperage Requirements	Circuit Breaker Size
Level 1 (120V)	120V	12-16 amps (varies by vehicle)	15-20 amps
Level 2 (240V)	240V	20-80 amps (depending on charger)	40-50 amps
DC Fast Charger	480V	100-200 amps (high-powered units)	100-200 amps

The breaker size determines how quickly your car will charge, so pick the right one to match your charger’s needs.

What Voltage Should Your Circuit Breaker Support?

Your circuit breaker needs to match your charger’s voltage. If you’re using a Level 1 charger, it runs on a standard 120V outlet, so you’ll need a breaker that supports 120V.

For a Level 2 charger, which uses 240V, you’ll need a breaker that supports that higher voltage. Fast chargers go even higher, so make sure to check the specs before installing.

Understanding the Electrical Code Requirements for EV Chargers

Now, here’s where things get a little technical: Electrical codes. If you’re in the U.S., you’ll need to follow the National Electrical Code (NEC) when installing your EV charger. This ensures safety and protects your home and electrical system from potential issues.

For example:

• NEC Section 625 talks about electric vehicle charging systems, including wiring methods and grounding.
  
• NEC 625.54 dictates the minimum wiring sizes for residential EV chargers, usually requiring 8 AWG copper for Level 2 chargers.
  

If you’re doing this yourself, make sure to consult these codes. If you’re not sure, calling in a licensed electrician is always a smart move.

Why Choose a GFCI or AFCI Circuit Breaker for Your EV Charger?

If your EV charger is going outdoors or in a damp environment, you need to pick a GFCI circuit breaker. Why? 

Because moisture and electricity don’t mix. A GFCI detects when electricity is leaking and shuts it off before you get shocked.

An AFCI breaker, on the other hand, is crucial if you’re installing a charger in an older home. This breaker detects faulty wiring or dangerous electrical arcs and prevents fires. 

These breakers add an extra layer of safety, and in some areas, they’re required by law.

What size mcb for 7.4 kw EV charger?

When selecting an MCB (Miniature Circuit Breaker) for a 7.4 kW EV charger, it’s essential to calculate the required amperage for the charger, and then match it with the right MCB size.

1. Power Calculation:
   
   • Power (in watts) = Voltage x Current
     
   • For a 7.4 kW charger (which is commonly a Level 2 EV charger), we calculate the amperage as follows:
     
     • 7.4 kW = 7400 watts
       
     • Assuming you’re using 230V (typical in many countries), the current required will be:
       Current=7400W230V=32.17 amps\text{Current} = \frac{7400W}{230V} = 32.17 \text{ amps}Current=230V7400W​=32.17 amps
       
2. Breaker Sizing:
   A 32AMCB would be ideal for a 7.4 kW EV charger. However, it’s always a good idea to size the breaker slightly above the charger’s current draw for safety and to account for possible fluctuations in power. Typically, you’ll need:
   
   • 32A or 40A MCB for a 7.4 kW charger.
     
3. Make sure to check your EV charger manufacturer’s guidelines, as they may recommend specific breaker sizes based on your model.

What type of MCB is required for EV charging?

For EV charging, a Type C MCB is often used. Here’s why:

• Type C MCB:
  
  • Type C breakers trip at 5-10 times the rated current, making them suitable for devices like electric vehicle chargers that may have brief inrush currents during startup.
    
  • The C curve is best for devices with moderate inrush current and is typically used in residential settings for EV chargers.
    
• Type B or Type D MCBs may be used in some specific setups, but Type C is most common for Level 2 residential chargers.
  

Also, it’s often recommended to use an RCD or GFCI (Ground Fault Circuit Interrupter) with your EV charger for safety. These devices will protect against any leakage of electricity, especially important for outdoor charging setups.

How many watts can A 20 amp breaker handle?

To calculate how many watts a 20A breaker can handle, you use the following formula:

Power (in watts) = Voltage x Current

• Assuming 230V (typical for residential charging in many countries):
  20A×230V=4600W20A \times 230V = 4600W20A×230V=4600W
  

So, a 20A breaker can safely handle about 4600 watts.

• For 240V systems, a 20A breaker can handle around 4800 watts.
  

Note: Never exceed 80% of the breaker’s rated capacity for continuous use (NEC recommends this). So, a 20A breaker should be used for a max 16A continuous load for better safety.

What is the best circuit breaker?

The “best” circuit breaker depends on your specific needs, but for EV charging at home, here are the recommended features:

1. MCB Type C: As mentioned earlier, a Type C MCB is ideal for handling moderate inrush currents associated with EV chargers.
   
2. RCD or GFCI: It’s recommended to use an RCD (Residual Current Device) or GFCI (Ground Fault Circuit Interrupter) for additional protection. These devices protect against electric shock or leakage currents, especially important in areas with higher moisture (like garages).
   
3. High-Quality Brands: Look for reputable brands like Schneider Electric, Siemens, or Legrand for reliable and safe breakers.

Best Circuit Breaker Brands for EV Charging in the US

Brand	Reputation	Popular Features	Best For
Schneider Electric	Highly trusted in residential and commercial setups.	Offers Type C MCBs, RCDs, GFCIs, and surge protection.	Comprehensive range for both home and commercial charging stations.
Siemens	Known for high-quality, reliable circuit breakers.	Type B and Type C MCBs, arc fault protection, and RCDs.	Excellent for residential installations and safety features.
Legrand	Leading brand in electrical solutions for homes and industries.	Offers Type C MCBs, surge protection, and RCDs.	Great for both home and commercial EV chargers, with easy installation features.
Eaton	Trusted for innovation and durable breakers.	Type C MCBs, ground fault protection, and arc fault circuit interrupters (AFCIs).	Ideal for heavy-duty and industrial installations.
Square D (by Schneider)	One of the most well-known brands in electrical equipment.	Offers Type C, Type B, GFCI breakers, and surge protectors.	Popular for high-quality residential and industrial use.
Cutler-Hammer (Eaton)	Known for reliability and long-lasting performance.	Type C MCBs, RCDs, high amp breakers.	Suitable for both residential and heavy-duty commercial EV charger installations.

How to Choose the Right EV Charger Installation Service

How to Wire a Level 1 EV Charger: NEC Rules You Need to Know

Wiring a Level 1 EV charger is pretty straightforward and doesn’t require any heavy-duty electrical work, especially since you’re using a standard 120V outlet. But that doesn’t mean you can skip over the safety rules, especially the NEC guidelines (National Electrical Code). Let’s walk through the process, step by step.

Step 1: Breaker Size

For a Level 1 charger, which is the kind that plugs into a regular 120V outlet (just like your household appliances), you typically use either a 15-amp or 20-amp breaker.

• 15-amp breaker: Suitable for basic charging needs where the current draw is modest.
  
• 20-amp breaker: Provides a bit more headroom in case your charger needs more power, especially for certain vehicles that draw a little more juice.
  

Always match the breaker size with your charger’s power draw, which is usually specified in the owner’s manual.

Step 2: Choosing the Right Wire Gauge

Wire size is crucial for safely carrying electricity from the circuit breaker to your charger. For a Level 1 charger, the wire gauge will vary depending on the amperage of your circuit:

• 14 AWG copper wire: For a 15-amp circuit.
  
• 12 AWG copper wire: For a 20-amp circuit.
  

The NEC recommends these wire gauges to ensure your charger’s power flow is safe without risking overheating or fire hazards.

Step 3: Installing the Outlet

Since you’ll be using a standard 120V outlet for your Level 1 charger, the next thing to make sure of is that the outlet is dedicated—meaning no other devices share that circuit. This is key for safety; the outlet should only serve the charger.

• A standard 3-prong outlet (NEMA 5-15) or a 4-prong outlet (NEMA 5-20) will work for a 120V circuit.
  
• If you’re installing this yourself, NEC Section 625.54 recommends grounding your outlet properly to avoid electrical shocks in case of faults.
  

Step 4: Circuit Breaker Location

The NEC requires that the circuit breaker controlling the outlet for your Level 1 charger be clearly labeled and easily accessible. In case of an emergency or when maintenance is required, you need to be able to identify and shut off the breaker quickly.

• NEC 110.25 requires clear labeling and easy access to circuit breakers, and that includes your EV charger.
  

Step 5: Testing the Circuit

Once everything’s wired up, it’s time to test the circuit! Flip the breaker, plug in the charger, and turn it on. The breaker should not trip, and your charger should start working.

• If your charger is working without problems and there’s no flickering of the breaker, you’ve wired it correctly!
  

Summary of NEC Requirements for Level 1 Wiring:

• Breaker Size: 15 or 20 amps, depending on the charger’s draw.
  
• Wire Gauge: 14 AWG for 15 amps, 12 AWG for 20 amps.
  
• Outlet: 120V, dedicated circuit.
  
• Grounding: Proper grounding for safety.
  
• Breaker Location: Accessible and clearly labeled.
  

How to Wire a Level 2 EV Charger: NEC Rules Explained

Now, let’s dive into Level 2 chargers, which are much more powerful and require more attention to detail when it comes to wiring. These chargers use 240V outlets, so you’ll be dealing with larger wire sizes and stronger breakers to safely handle the power load.

Step 1: Choosing the Right Breaker Size

For Level 2 chargers, which charge your EV much faster than a Level 1 charger, you’ll need a 240V circuit and a stronger circuit breaker. Here are the general guidelines:

• 40-50 amp breaker: This is standard for most residential Level 2 chargers. It gives your car the proper charging speed without overloading the system.
  
• 100 amp or more: This is typically needed for DC Fast Chargers or higher-powered chargers used in commercial settings.
  

To determine the exact breaker size, check your charger’s manual. The amperage rating on the charger should guide your breaker choice.

Step 2: Selecting the Right Wire Gauge

For Level 2 chargers, the wire size is bigger because more power is needed:

• 10 AWG copper wire for a 30-amp circuit.
  
• 8 AWG copper wire for 40-50 amp circuits.
  

The NEC requires these wire sizes to safely carry the increased current without heating up or causing fire hazards. The thicker the wire, the safer the electrical flow.

Step 3: Installing the 240V Outlet

A Level 2 charger uses a 240V outlet—much different from the standard 120V outlet you’d use for a Level 1 charger.

• NEMA 6-50: This is the most common 240V outlet for residential setups. It’s typically used for dryers and large appliances, making it a great fit for your Level 2 charger.
  
• NEMA 14-50: This is another outlet type that works with some high-powered Level 2 chargers.
  

You must use a dedicated 240V circuit for your EV charger. No other appliances should share this circuit.

Step 4: Following NEC Guidelines for Proper Grounding

The NEC 625.54 mandates that all Level 2 chargers be properly grounded to prevent electrical shock hazards. Grounding gives the current a safe path to follow in case something goes wrong.

• Be sure to use a grounding conductor when wiring your 240V outlet to your circuit breaker.
  

Step 5: Installing the Circuit Breaker

Now that the outlet is installed, it’s time to wire everything to the breaker panel. For a Level 2 charger, use the correct amp-rated breaker. A 40-50 amp breaker is the most common for residential installations.

• Your circuit breaker panel should have a dedicated space for this circuit, and the breaker must be clearly marked for easy identification.
  

Step 6: Testing the Charger

Once everything is wired up, turn on the breaker and plug in your Level 2 charger. If the charger powers up without any issues, you’ve done it right. Double-check that the breaker doesn’t trip during the charging process, and ensure the outlet and wiring remain cool to the touch.

Summary of NEC Requirements for Level 2 Wiring:

• Breaker Size: 40-50 amps for typical Level 2 chargers; higher for commercial units.
  
• Wire Gauge: 10 AWG for 30 amps, 8 AWG for 40-50 amps.
  
• Outlet: 240V, use NEMA 6-50 or 14-50 receptacle.
  
• Grounding: Proper grounding is essential for safety.
  
• Breaker Location: Accessible, labeled, and dedicated to the charger.
  

FAQ Section:

1. What happens if I choose the wrong circuit breaker for my EV charger?
   
   • Choosing the wrong breaker can lead to constant tripping, damage to your charger, or even fires. Make sure the breaker matches your charger’s amperage and voltage.
     
2. Can I install my EV charger circuit breaker myself?
   
   • If you’re comfortable working with electrical systems and follow NEC guidelines, you can install it yourself. If not, it’s safer to hire a licensed electrician.
     
3. Do I need a GFCI breaker for my Level 1 EV charger?
   
   • While it’s not strictly required for indoor installations, if your charger is outdoors or in a damp area, a GFCI breaker is highly recommended.
     
4. How do I know if my wiring is up to code?
   
   • Always consult the NEC codes and check the wire gauge, breaker size, and outlet type. If in doubt, call an electrician to ensure your setup is compliant.
     
5. What’s the difference between a Level 1 and Level 2 charger’s wiring?
   
   • Level 1 chargers use standard 120V outlets and require minimal wiring, while Level 2 chargers use 240V outlets and require thicker wires and a dedicated circuit.

Conclusion

From choosing the correct amperage rating and voltage to understanding NEC compliance, selecting the right breaker involves ensuring safety and meeting local regulations. Type C MCBs are ideal for Level 2 residential chargers, while MCCBs and AFCIs are used for high-powered or industrial systems. 

Additionally, RCDs or GFCIs are essential for outdoor installations or areas prone to moisture.