Three-phase voltage, frequency and
number of wires

Although single-phase power is more prevalent today, three phase is still chosen as the power of choice for many different types of applications. Generators at power stations supply three-phase electricity. This is a way of supplying three times as much electricity along three wires as can be supplied through two, without having to increase the thickness of the wires. It is usually used in industry to drive motors and other devices.

Three-phase electricity is by its very nature a much smoother form of electricity than single-phase or two-phase power. It is this more consistent electrical power that allows machines to run more efficiently and last many years longer than their relative machines running on the other phases. Some applications are able to work with three-phase power in ways that would not work on single phase at all.

Mind you, since three-phase electricity is rarely used for domestic purposes, the table below is only relevant to electricians, electrical engineers and other technically skilled people. Travelers should take a look at the single-phase voltage table. Look-up table (single-phase voltage, frequency and plug/sockets)

* In Brazil there is no standard voltage. Most states use 127 V electricity (single-phase) and 220 V (three-phase) (Acre, Amapá, Amazonas, Espírito Santo, Mato Grosso do Sul, Maranhão, Pará, Paraná, Rondônia, Roraima, Sergipe and Minas Gerais). Other – mainly northeastern – states are on 220 V (single-phase) and 380 V (three-phase) (Alagoas, Brasília, Ceará, Mato Grosso, Goiás, Paraíba, Rio Grande do Norte, Santa Catarina and Tocantins). Although in most parts of the states of Bahia, São Paulo, Rio de Janeiro and Rio Grande do Sul 127 V (single-phase) and 220 V (three-phase) is used, the cities of Santos, Jequié, Jundiaí, São Bernardo do Campo, Novo Friburgo, Bagé, Caxias do Sul and Pelotas run on 220 V (single-phase) and 380 V (three-phase). The states of Pernambuco and Piauí use 220 V (single-phase) and 380 V (three-phase), except for the cities of Paulista and Teresina (127 V single-phase and 220 V three-phase).

** Although the mains voltage in Japan is the same everywhere, the frequency differs from region to region. Eastern Japan uses predominantly 50 Hz (Tokyo, Kawasaki, Sapporo, Yokohama, Sendai), whereas Western Japan prefers 60 Hz (Osaka, Kyoto, Nagoya, Hiroshima).

*** In most parts of Saudi Arabia - such as the Dammam and al-Khobar area - 190 V three-phase electricity is used (110 V single-phase). 220 V (single-phase) and 380 V (three-phase) can be found as well.

**** In Tahiti the frequency is 60 Hz, except for the Marquesas archipelago where it is 50 Hz.