What is a sub panel?
A sub panel is an extension of your home’s main electrical panel. It is a smaller electrical panel that is connected to your main electrical panel and is typically installed in the basement for a future basement finish. Sub panels achieve two things: (1) it brings power closer to where power will be needed in the future and (2) provides more space for installing new circuit breakers.

Do I need a sub panel for my basement? Can’t I just use my main electrical panel?
If you plan on finishing the basement in your home, a sub panel will likely be needed. In a typical home, your main electrical panel will likely only have one or two spaces for additional circuit breakers in the future. This is not an adequate amount of space to finish a basement. A sub panel will provide you with more space for additional circuit breakers needed for a basement to be finished as well as be in a more convenient location for shutting power off.
Installing a sub panel can also help save you time and money. Sub panels reduce the need for multiple ‘home runs’ back to the main electrical panel, which can be costly. This in turn will reduce the amount of materials and labor needed.