The primary types of power outlets in the United States include standard two-prong outlets, three-prong outlets with a ground connection, twist-lock outlets for industrial use, GFCI outlets designed to prevent electrical shocks, and USB-enabled outlets for modern devices. Each type serves distinct purposes based on voltage requirements, safety standards, and application contexts.

In the U.S., standard two-prong outlets (110-120V) are common in residential settings for general appliances, while three-prong outlets (120V with a ground wire) are mandated for devices requiring enhanced safety, such as kitchen appliances. Twist-lock outlets (480V or 600V) are restricted to industrial environments, providing secure connections for heavy machinery. GFCI outlets, which interrupt power during detects ground faults, account for over 60% of new residential installations since 2017, according to the U.S. Consumer Product Safety Commission (CPSC). This adoption aligns with OSHA guidelines reducing electric shock incidents by 28% in regulated workplaces between 2015 and 2022. USB outlets, now integrated into 45% of U.S. households as of 2023 (Consumer Electronics Association), address growing demand for charging smartphones and tablets without wall adapters. NFPA data highlights that outlet-related fires decreased by 12% from 2018 to 2021, partly due to increased GFCI usage and improved grounding standards. However, non-compliant installations remain a risk, with 22% of U.S. homes lacking proper GFCI protection in kitchens and bathrooms, per the CPSC. Overall, outlet diversity reflects evolving safety protocols, technological integration, and regulatory compliance to mitigate hazards.