A two-prong or NEMA 1-15 connector is used for light domestic uses and appliances that do not draw heavy energy loads or require grounding. These include lamps, clocks, radios, small electronics such as cell phone chargers, and other electrical devices requiring fewer than 15 amps or 125 volts of current.
These plugs are not grounded and are not suitable for heavy-duty or commercial use or for energy-hungry cooling and heating equipment. They are no longer permitted in new construction in the United States and Canada. Two-prong plugs may be polarized, with one prong slightly taller and narrower than the other to prevent a polarized plug from being inserted into a neutral socket, which is normally wider than the polarized prong.