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.
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.
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 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.
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 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 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.
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.
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
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.
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 |
Bangladesh |
220V |
50Hz |
Barbados |
115V |
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 |
Canada |
120V |
60Hz |
Canary Islands |
230V |
50Hz |
Cape Verde |
230V |
50Hz |
Cayman Islands |
120V |
60Hz |
Central Africa |
220V |
50Hz |
Chad |
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 |
Ecuador |
127V |
60Hz |
Egypt |
220V |
50Hz |
El Salvador |
115V |
60Hz |
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 |
Grenada |
230V |
50Hz |
Guadeloupe |
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 |
|
|
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 |
Madagascar |
127/220V |
50Hz |
Madeira |
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 |
Trinidad & Tobago |
115V |
60Hz |
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.
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.
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.
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. |