Brainstuff

A normal 120 volt outlet in the US has two vertical slots and a role hole centered below the slots -- the outlets with a pair of red and black 'test' and 'reset' buttons are known as GCFI outlets. Check out this HowStuffWorks podcast to learn more. Learn more about your ad-choices at https://www.iheartpodcastnetwork.com See omnystudio.com/listener for privacy information.