Shown in number of hertz (cycles per second). Note that even if voltages are similar, a 60-hertz U.S. clock or tape recorder will not function properly on 50 hertz current. [1]

The term nominal voltage is used to denote the reported voltage in use in the majority of residential and commercial establishments in the country or city. Direct current nominal voltages are 110/220 and 120/240. The lower voltage is always 1/2 of the higher voltage. On a direct current installation, the lower voltage requires two wires while the higher voltage requires three wires.

Alternating current is normally distributed either through 3 phase wye (“star”) or delta (“triangle”), 4-wire secondary distribution systems. In the wye or star distribution system the nominal voltage examples are 120/208, 127/220, 220/380, and 230/400. The higher voltage is 1.732 (the square root of 3) times the lower voltage. In a delta or triangle system, 110/220 and 230/460 are examples of nominal voltages. The higher voltage is always double the lower voltage. The higher voltage is obtained by using 2 or 3 phase wires and the neutral wire while the lower voltage is the voltage between the neutral wire and one phase wire. The higher voltage may be single or 3 phase while the lower voltage is always single phase and used primarily for lighting and for small appliances. [2]

Attachment plugs used throughout the world come in too many forms, dimensions and configurations catalog here. This site does, however, attempt to point out the basic and most commonly used types of plugs by country. Adapters may be purchased to change a common plug type to other types. [3]

In the charts of country information, “Yes” in this field indicates that the frequency is stable and that service interruptions are rare. [HIDE MAP]