How to Determine Your Main Breaker Size

How to identify your main breaker

To calculate how much energy your home has available for an EV charger it is important to identify your home’s electrical service size which can be determined by the main breaker. In order to do that we need to start by identifying your main breaker panel. Many homes will have more than one breaker panel. The main electrical panel is where the service first enters your home. Often times the electrical meter will be located on a shared exterior wall with the main electrical panel but this is not always the case. You should be able to locate where a conduit or cable runs from your electrical meter to the inside of your house and reaches your main panel. See the image above for an example.

Your home may have more than one electrical panel. Generally, the main breaker is going to have the highest value of any of the breakers on the electrical panels in your home. In the example above, this home has a subpanel which is right beside the main electrical panel. Subpanels can often be in different locations of the house or in a different structure such as a detached garage. Some panels will actually label the main breaker as you can see in the example below.

As you can see in this example, the main breaker value is 100 amps. Common main breaker sizes are 100, 150, or 200 amps.

Main breaker