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Electricity

Worldwide AC Voltages and Frequencies

The voltage and frequency of alternating current (AC) electricity used in homes varies from country to country throughout the world. Typically either 110-volt AC (110V) or 220-volt AC (220V) are used. Note that 110 volts and 220 volts are averages, since the voltage does fluctuate during usage. Most countries use 50Hz (50 Hertz or 50 cycles per second) as the frequency of their AC. Only a handful use 60Hz. The United States uses 110V and 60Hz AC electricity.

Questions you may have about AC electricity are:

• How were the voltage and frequency values selected?

• What happens when you visit another country?

• What is the listing for the various countries?

How values were selected

The type of electricity delivered to homes and businesses was first direct current (DC) but then changed to AC electricity. The standard voltage level started at 110V, went to 240V, back to 110V, and then to 220V. The frequency started at 60Hz and then went to 50Hz in most areas.

Tesla starts AC

Early in the history or electricity, Thomas Edison's General Electric company was distributing DC electricity at 110 volts in the United States. Then Nikola Tesla the devised a system of three-phase AC electricity at 240 volts. Three-phase meant that three alternating currents slightly out of phase were combined in order to even out the great variations in voltage occurring in AC electricity. He had calculated that 60 cycles per second or 60Hz was the most effective frequency. Tesla later compromised to reduce the voltage to 110 volts for safety reasons.

Europe goes to 50Hz

With the backing of the Westinghouse Company, Tesla's AC system became the standard in the United States. Meanwhile, the German company AEG started generating electricity and became a virtual monopoly in Europe. They decided to use 50Hz instead of 60Hz to better fit their metric standards, but they kept the voltage at 110V.

Unfortunately, 50Hz AC has greater losses and is not as efficient as 60HZ. Due to the slower speed 50Hz electrical generators are 20% less effective than 60Hz generators. Electrical transmission at 50Hz is about 10-15% less efficient. 50Hz transformers require larger windings and 50Hz electric motors are less efficient than those meant to run at 60Hz. They are more costly to make to handle the electrical losses and the extra heat generated at the lower frequency.

Europe goes to 220V

Europe stayed at 110V AC until the 1950s, just after World War II. They then switched over to 220V for better efficiency in electrical transmission. Great Britain not only switched to 220V, but they also changed from 60Hz to 50Hz to follow the European lead. Since many people did not yet have electrical appliances in Europe after the war, the change-over was not that expensive for them.

U.S. stays at 110V, 60Hz

The United States also considered converting to 220V for home use but felt it would be too costly, due to all the 110V electrical appliances people had. A compromise was made in the U.S. in that 220V would come into the house where it would be split to 110V to power most appliances. Certain household appliances such as the electric stove and electric clothes dryer would be powered at 220V.

When visiting another country

Bringing an electrical appliance from one country to another may require some special converters, transformers and adapters to allow the appliance or device to work properly.

Converters

Converters are typically used to decrease the AC voltage from 220V to the 110V level needed by the appliance.

They are only used for simple electrical products such as hair dryers, steam irons, shavers, or small fans. They are only used for short periods of time, can only be used for ungrounded appliances, and must be unplugged from the wall when not in use.

Converters cannot be used by electronic devices such as radios or computers. A transformer is used for those devices. The reason is that a converter simply cuts the AC sine wave in half, reducing the voltage. Electronic devices need the full sine wave to function properly.

Some converters will also change AC to DC. An example is converting 120V AC to 12V DC.

Transformers

Transformers are used to increase or decrease the voltage and should be used with electronic devices such as radios, televisions, computers and other devices having electronics circuitry.

Transformers are more expensive than converters. They can also be used with electric appliances and may be operated continually for many days. A device like a hair dryer does not have any electronic circuitry. It simply has a heater element and electric fan, so it and can use either a converter or transformer.

Dual voltage devices

Some devices have a built-in converter or transformer, such that they are called dual voltage devices. Most laptop battery chargers and AC adapters are dual voltage, so they can be used with only a plug adapter for the country you are visiting.

Outlet plugs are different in the various countries. Plug adapter must often be used when visiting a different country. These adapters do not convert electricity. Rather, they simply allow a dual voltage appliance, transformer or converter from one country to be plugged into the wall outlet of another country.

Frequency difference

Converters and transformers only change the voltage and not the frequency. The result is that a motor in a 50Hz appliance will operate slightly faster on 60Hz electricity. Likewise, a clock made for 60Hz will run slower in a country using the 50Hz frequency.

Most modern electronic equipment like computers, printers, DVD players and stereos are usually not affected by the frequency difference

Country listing

Of the over 200 countries listed below, less than 40 use 110V. Some countries use dual voltages. 43 countries use 60Hz, while the rest use 50Hz.

Country Voltage Frequency
Afghanistan 220V 50Hz
Albania 230V 50Hz
Algeria 230V 50Hz
American Samoa 120V 60Hz
Andorra 230V 50Hz
Angola 220V 50Hz
Anguilla 110V 60Hz
Antigua 230V 60Hz
Argentina 220V 50Hz
Armenia 230V 50Hz
Aruba 127V 60Hz
Australia 240V 50Hz
Austria 230V 50Hz
Azerbaijan 220V 50Hz
Azores 230V 50Hz
Bahamas 120V 60Hz
Bahrain 230V 50Hz
Balearic Islands 230V 50Hz
Belarus 230V 50Hz
Belgium 230V 50Hz
Belize 110/220V 60Hz
Benin 220V 50Hz
Bermuda 120V 60Hz
Bhutan 230V 50Hz
Bolivia 230V 50Hz
Bosnia 230V 50Hz
Botswana 230V 50Hz
Brazil 110-220V 60Hz
Brunei 240V 50Hz
Bulgaria 230V 50Hz
Burkina Faso 220V 50Hz
Burundi 220V 50Hz
Cambodia 230V 50Hz
Cameroon 220V 50Hz
Canary Islands 230V 50Hz
Cape Verde 230V 50Hz
Cayman Islands 120V 60Hz
Central Africa 220V 50Hz
Channel Islands 230V 50Hz
Chile 220V 50Hz
China 220V 50Hz
Colombia 110V 60Hz
Comoros 220V 50Hz
Congo (Zaire) 220V 50Hz
Cook Islands 240V 50Hz
Costa Rica 120V 60Hz
Côte d'Ivoire
(Ivory Coast)
220V 50Hz
Croatia 230V 50Hz
Cuba 110/220V 60Hz
Cyprus 230V 50Hz
Czech Republic 230V 50Hz
Denmark 230V 50Hz
Djibouti 220V 50Hz
Dominica 230V 50Hz
Dominican Republic 110V 60Hz
East Timor 220V 50Hz
Egypt 220V 50Hz
Equatorial Guinea 220V 50Hz
Eritrea 230V 50Hz
Estonia 230V 50Hz
Ethiopia 220V 50Hz
Faeroe Islands 230V 50Hz
Falkland Islands 240V 50Hz
Fiji 240V 50Hz
Finland 230V 50Hz
France 230V 50Hz
French Guyana 220V 50Hz
Gaza 230V 50Hz
Gabon 220V 50Hz
Gambia 230V 50Hz
Germany 230V 50Hz
Ghana 230V 50Hz
Gibraltar 230V 50Hz
Greece 230V 50Hz
Greenland 230V 50Hz
Guam 110V 60Hz
Guatemala 120V 60Hz
Guinea 220V 50Hz
Guinea-Bissau 220V 50Hz
Guyana 240V 60Hz
Haiti 110V 60Hz
Honduras 110V 60Hz
Hong Kong 220V 50Hz
Hungary 230V 50Hz
Iceland 230V 50Hz
India 240V 50Hz
Indonesia 230V 50Hz
Iran 230V 50Hz
Iraq 230V 50Hz
Ireland (Eire) 230V 50Hz
Isle of Man 230V 50Hz
Israel 230V 50Hz
Italy 230V 50Hz
Jamaica 110V 50Hz
Japan 100V 50/60Hz
Jordan 230V 50Hz
Kenya 240V 50Hz
Kazakhstan 220V 50Hz

Country Voltage Frequency.
Kiribati 240V 50Hz
Korea, South 220V 60Hz
Kuwait 240V 50Hz
Kyrgyzstan 220V 50Hz
Laos 230V 50Hz
Latvia 230V 50Hz
Lebanon 230V 50Hz
Lesotho 220V 50Hz
Liberia 120V 60Hz
Libya 127/230V 50Hz
Lithuania 230V 50Hz
Liechtenstein 230V 50Hz
Luxembourg 230V 50Hz
Macau 220V 50Hz
Macedonia 230V 50Hz
Malawi 230V 50Hz
Malaysia 240V 50Hz
Maldives 230V 50Hz
Mali 220V 50Hz
Malta 230V 50Hz
Martinique 220V 50Hz
Mauritania 220V 50Hz
Mauritius 230V 50Hz
Mexico 127V 60Hz
Micronesia 120V 60Hz
Moldova 230V 50Hz
Monaco 230V 50Hz
Mongolia 230V 50Hz
Montserrat Islands 230V 60Hz
Morocco 220V 50Hz
Mozambique 220V 50Hz
Myanmar (Burma) 230V 50Hz
Namibia 220V 50Hz
Nauru 240V 50Hz
Nepal 230V 50Hz
Netherlands 230V 50Hz
Netherlands Antilles 127/220V 50Hz
New Caledonia 220V 50Hz
New Zealand 230V 50Hz
Nicaragua 120V 60Hz
Niger 220V 50Hz
Nigeria 240V 50Hz
Norway 230V 50Hz
Okinawa 100V 60Hz
Oman 240V 50Hz
Pakistan 230V 50Hz
Palmyra Atoll 120V 60Hz
Panama 110V 60Hz
Papua New Guinea 240V 50Hz
Paraguay 220V 50Hz
Peru 220V 60Hz
Philippines 220V 60Hz
Poland 230V 50Hz
Portugal 230V 50Hz
Puerto Rico 120V 60Hz
Qatar 240V 50Hz
Réunion Island 230V 50Hz
Romania 230V 50Hz
Russian Federation 230V 50Hz
Rwanda 230V 50Hz
St. Kitts & Nevis Islands 230V 60Hz
St. Lucia Island 240V 50Hz
St. Vincent Island 230V 50Hz
Saudi Arabia 127/220V 60Hz
Senegal 230V 50Hz
Serbia & Montenegro 230V 50Hz
Seychelles 240V 50Hz
Sierra Leone 230V 50Hz
Singapore 230V 50Hz
Slovakia 230V 50Hz
Slovenia 230V 50Hz
Somalia 220V 50Hz
South Africa 230V 50Hz
Spain 230V 50Hz
Sri Lanka 230V 50Hz
Sudan 230V 50Hz
Suriname 127V 60Hz
Swaziland 230V 50Hz
Sweden 230V 50Hz
Switzerland 230V 50Hz
Syria 220V 50Hz
Tahiti 110/220V 60Hz
Tajikistan 220V 50Hz
Taiwan 110V 60Hz
Tanzania 230V 50Hz
Thailand 220V 50Hz
Togo 220V 50Hz
Tonga 240V 50Hz
Tunisia 230V 50Hz
Turkey 230V 50Hz
Turkmenistan 220V 50Hz
Uganda 240V 50Hz
Ukraine 230V 50Hz
United Arab Emirates 220V 50Hz
United Kingdom 230V 50Hz
United States 110/220V 60Hz
Uruguay 220V 50Hz
Uzbekistan 220V 50Hz
Venezuela 120V 60Hz
Vietnam 220V 50Hz
Virgin Islands 110V 60Hz
Western Samoa 230V 50Hz
Yemen 230V 50Hz
Zambia 230V 50Hz
Zimbabwe 220V 50Hz

Exceptions

Some countries can't decide on a standard.

Brazil

In Brazil, most states use between 110V and 127V AC electricity. But many hotels use 220V. In the capital Brasilia and in the northeast of the country, they mainly use 220-240V.

Japan

In Japan, they use the same voltage everywhere, but the frequency differs from region to region. Eastern Japan, which includes Tokyo, uses 50Hz. In western Japan, which includes Osaka and Kyoto, they use 60 Hz.

The reason for this is that after World War II, Britain was in charge of helping reconstruct Japan's electrical system in the easter part of the country and the United States set up the electricity in the western part of Japan. Since Great Britain (United Kingdom) had been using 60Hz before the war and had just switched over to the European 240V 50Hz, it is strange that they set up Japan at 100V and 50Hz, especially when the U.S. was using 60Hz.

Having different voltages and frequencies within the country not only must be confusing for the people but also can result in extra costs for appliances and adapters.

In conclusion

The voltage and frequency of AC electricity varies from country to country throughout the world. Most use 220V and 50Hz. About 20% of the countries use 110V and/or 60Hz to power their homes. 220V and 60Hz are the most efficient values, but only a few countries use that combination. The United States uses 110V and 60Hz AC electricity.