This chart shows the main connector types that are used in North America. Beginning with the two NEMA plugs depicted in the top left picture, the NEMA 1-15 receptacles and plugs are still in use in millions of buildings built before the 1960s. All NEMA 1 devices, which is referring to the number preceding the hyphen, are two-wire non-grounding devices typically rated for 125 V. The number following the hyphen, in this case 15, is the current rating in amperes. The last letter, either “P” or “R” indicates whether the connector is a plug or receptacle. All NEMA 5 devices are three-wire grounding devices (hot-neutral-ground) as shown earlier in this tutorial. The 5-15P is basically the three-wire, grounded version of its predecessor the 1-15P.  The remaining connectors depicted are standardized by the IEC for the connection of power cords to electrical devices and appliances up to 250 V. The C13 and C14 style connectors are very common today on personal computers and peripherals. The C7 connector depicted in the bottom right corner is available in polarized and non-polarized versions and often used for power supplies and audio/video equipment.