Type B Socket And Plug

American Standard

The Type B plug and socket (NEMA 5-15 specification) is currently used primarily in the United States, Canada, and Latin America.

The Type B plug consists of two parallel flat prongs and a round grounding pin. The two flat prongs are each 1.5 mm thick, 15.9 to 18.3 mm long, 6.3 mm wide, and spaced 12.7 mm apart. The round grounding pin has a diameter of 4.8 mm and extends 3.2 mm longer than the flat prongs. Because the ground pin is slightly longer than the other two prongs, the appliance is grounded before it is energized, ensuring safety. The Type B plug is rated for 15 amperes. Most modern Type B plugs are polarized, with the wider prong (7.9 mm) serving as the neutral and the narrower one (6.3 mm) as the live wire.

In some Latin American countries, Type B sockets are still not very common, so people often simply cut off the round grounding pin of the Type B plug and insert it into a two-hole Type A socket.

Japanese Standard

The Japanese standard Type B plug and socket (JIS C 8303, Class I specification) is essentially the same as the NEMA 5-15 specification, but this type of plug and socket was not common for a long time. Since 2005, the Japan Electrical Manufacturers' Association has recommended that all newly installed sockets adopt this specification, and it is mandatory for sockets used with washing machines, microwave ovens, and similar appliances.

Unlike the NEMA 5-15, some Japanese standard Type B sockets may have an additional grounding terminal, with the ground wire separately connected to this terminal.