is no standard mains voltage throughout the world and also the
frequency, i.e. the number of times the current changes direction per
second, is not everywhere the same. Moreover, plug shapes, plug
holes, plug sizes and sockets are also different in many countries.
Those seemingly unimportant differences, however, have some
Most appliances bought overseas
simply cannot be connected to the wall outlets at home.
it is easy to buy a plug adapter or a new "local" plug for
your "foreign" appliances, in many cases this only solves
half the problem, because it doesn't help with the possible voltage
disparity. A 110-volt electrical appliance designed for use in North
America or Japan will provide a nice fireworks display - complete
with sparks and smoke - if plugged into a European socket.
and most other countries in the world use a voltage which is twice
that of the US. It is between 220 and 240 volts, whereas in Japan and
in most of the Americas the voltage is between 100 and 127 volts.
system of three-phase alternating current electrical generation and
distribution was invented by a nineteenth century creative genius
named Nicola Tesla. He made many careful calculations and
measurements and found out that 60 Hz (Hertz, cycles per second) was
the best frequency for alternating current (AC) power generating. He
preferred 240 volts, which put him at odds with Thomas Edison, whose
direct current (DC) systems were 110 volts. Perhaps Edison had a
useful point in the safety factor of the lower voltage, but DC
couldn't provide the power to a distance that AC could.
the German company AEG built the first European generating facility,
its engineers decided to fix the frequency at 50 Hz, because the
number 60 didn't fit the metric standard unit sequence (1,2,5). At
that time, AEG had a virtual monopoly and their standard spread to
the rest of the continent. In Britain, differing frequencies
proliferated, and only after World War II the 50-cycle standard was
established. A big mistake, however. Not only is 50 Hz 20% less
effective in generation, it is 10-15% less efficient in transmission,
it requires up to 30% larger windings and magnetic core materials in
transformer construction. Electric motors are much less efficient at
the lower frequency, and must also be made more robust to handle the
electrical losses and the extra heat generated. Today, only a handful
of countries (Peru, Ecuador, Guyana, the Philippines and South Korea)
follow Tesla’s advice and use the 60 Hz frequency together with
a voltage of 220-240 V.
Europe was 110 V too, just like Japan and the US today. It has been
deemed necessary to increase voltage to get more power with less
losses and voltage drop from the same copper wire diameter. At the
time the US also wanted to change but because of the cost involved to
replace all electric appliances, they decided not to. At the time
(50s-60s) the average US household already had a fridge, a
washing-machine, etc., but not in Europe.
end result is that now, the US seems not to have evolved from the 50s
and 60s, and still copes with problems as light bulbs that burn out
rather quickly when they are close to the transformer (too high a
voltage), or just the other way round: not enough voltage at the end
of the line (105 to 127 volt spread !).
that currently all new American buildings get in fact 230 volts split
in two 115 between neutral and hot wire. Major appliances, such as
ovens, are now connected to 230 volts. Americans who have European
equipment, can connect it to these outlets.
In Brazil there is no standard voltage; most states use 110-127 V
electricity (Rio Grande do Sul, Paraná, São Paulo,
Minas Gerais, Bahia, Rio de Janeiro, Pará, Amazonas,…).
In many hotels, however, 220 V can be found. 220-240 V is used mainly
in the northeast: in the capital Brasilia (Distrito Federal) and,
among others, in the states of Ceará, Pernambuco and Santa
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, Yokohoma, Sendai),
whereas Western Japan prefers 60 Hz (Osaka, Kyoto, Nagoya,
electricity was first introduced into the domestic environment it was
primarily for lighting. However, as it became a viable alternative to
other means of heating and also the development of labour saving
appliances, a means of connection to the supply other than via a
light socket was required. In the 1920s, the two-prong plug made its
that time, some electricity companies operated a split tariff system
where the cost of electricity for lighting was lower than that for
other purposes, which led to low wattage appliances (e.g. vacuum
cleaners, hair dryers, etc.) being connected to the light fitting.
The picture below shows a 1909 electric toaster with a lightbulb
the need for safer installations grew, three-pin outlets were
developed. The third pin on the outlet was an earth pin, which was
effectively connected to earth, this being at the same potential as
the neutral supply line. The idea behind it was that in the event of
a short circuit to earth, a fuse would blow, thus disconnecting the
reason why we are now stuck with no less than 13 different styles of
plugs and wall outlets, is because many countries preferred to
develop a plug of their own, instead of adopting the US standard.
Moreover, the plugs and sockets are only very rarely compatible,
which makes it often necessary to replace the plug when you buy
is a brief outline of the plugs and sockets used around the world in
and Outlet Requiring Plug Adapter #3
in, among others, North and Central America and Japan)
class II ungrounded plug with two flat parallel prongs is pretty
much standard in most of North and Central America. At first
glance, the Japanese plug and socket seem to be identical to this
standard. However, the Japanese plug has two identical flat
prongs, whereas the US plug has one prong which is slightly
larger. Therefore it is no problem to use Japanese plugs in the
US, but the opposite does not work often. Furthermore, Japanese
standard wire sizes and the resulting current ratings are
different than those used on the American continent.
and Outlet Requiring Plug Adapter WA-5
in, among others, North and Central America and Japan)
is a class I plug with two flat parallel prongs and a grounding
pin (American standard NEMA 5-15/Canadian standard CS22.2, n°42).
It is rated at 15 amps and although this plug is also standard in
Japan, it is less frequently used than in North America.
Consequently, most appliances sold in Japan use a class II
ungrounded plug. As is the case with the type A standard, the
Japanese type B plugs and sockets are slightly different from
their American counterparts.
ungrounded version of the North American NEMA 5-15 plug is
commonly used in Central America and parts of South America. It
is therefore common for equipment users to simply cut off the
grounding pin that the plug can be mated with a two-pole
and Outlet Requiring Plug Adapters #1 & #6
in all countries of Europe except the United Kingdom, Ireland,
Cyprus and Malta)
two-wire plug is ungrounded and has two round prongs. It is
popularly known as the Europlug which is described in CEE 7/16.
This is probably the single most widely used international plug.
It will mate with any socket that accepts 4.0-4.8 mm round
contacts on 19 mm centres. It is commonly used in all countries
of Europe except the United Kingdom and Ireland. It is also used
in various parts of the developing world. This plug is generally
limited for use in class II applications that require 2.5 amps or
less. It is, of course, unpolarised.
and Outlet Requiring Plug Adapter #WA-10
almost exclusively in India, Sri Lanka, Nepal and Namibia)
has standardised on a plug which was originally defined in
British Standard 546 (the standard in Great Britain before 1962).
Although the WA-10 is now almost exclusively used in India, Sri
Lanka, Nepal and Namibia, it can still occasionally be found in
specialist applications such as hotels and theatres in the UK.
This plug has three large round pins in a triangular pattern. It
is rated at 5 amps. WA-10L, which has larger pins and is rated at
15 amps, is used alongside type WA-9 for larger appliances in
India, Sri Lanka, Nepal and Namibia. Some sockets can take both
type WA-10 and WA-10L plugs.
and Outlet Requiring Plug Adapter #WA-9
used in France, Belgium, Poland, Slovakia, the Czech Republic,
Tunisia and Morocco)
Belgium and some other countries have standardised on a socket
which is different from the CEE 7/4 socket that is standard in
Germany and other continental European countries. The reason for
incompatibility is that grounding in the this socket is
accomplished with a round male pin permanently mounted in the
socket. The plug itself is similar to #1 & #6 except that it
is round and has the addition of a female contact to accept the
grounding pin in the socket. In order to bridge the differences
between these sockets , the CEE 7/7 plug was developed: it has
grounding clips on both sides to mate with the metal grounding
clips in the socket and a female contact to accept the grounding
pin of that type socket. The original plug, which does not have
grounding clips, is no longer used, although very rarely it can
still be found on some older appliances. Note that the CEE 7/7
plug is polarised when used with the outlet with the ground pin.
The plug is rated at 16 amps. Above that, equipment must either
be wired permanently to the mains or connected via another higher
power connector such as the IEC 309 system.
and Outlet Requiring Plug Adapter #WA-9
in, among others, Germany, Austria, the Netherlands, Sweden,
Norway, Finland, Portugal, Spain and Eastern Europe)
known as CEE 7/4 and commonly called "Schuko plug", is
similar to #1 & #6 except that it is round and has the
addition of two grounding clips on the side of the plug. It has
two 4.8 mm round contacts on 19 mm centres. Because the CEE 7/4
plug can be inserted in either direction into the receptacle, the
Schuko connection system is unpolarised (i.e. line and neutral
are connected at random). It is used in applications up to 16
amps. Above that, equipment must either be wired permanently to
the mains or connected via another higher power connector such as
the IEC 309 system. In order to bridge the differences between
these similar sockets , the CEE 7/7 plug was developed. This
plug, which is shown above, has grounding clips on both sides to
mate with the type F socket and a female contact to accept the
grounding pin of the type E socket. The original plug, which does
not have this female contact, is still available at the DIY shops
but only in a rewireable version.
Soviet Republics use a standard plug and socket defined in
Russian Standard Gost 7396 which is similar to the Schuko
standard. Contacts are also on 19 mm centres, but the diameter of
this contact is 4.0 mm compared to 4.8 mm which is standard in
Continental Europe. It is possible to mate Russian plugs with
Schuko outlets, but Russian sockets will not allow to connect
type E and F plugs as the outlets have smaller hole diameters
than the pins of those two plugs mentioned. Many official
standards in Eastern Europe are virtually identical to the Schuko
standard. Furthermore, one of the protocols governing the
reunification of Germany provided that the DIN and VDE standards
would prevail without exception. The former East Germany was
required to confirm to the Schuko standard. It appears that most
if not all of the Eastern European countries generally use the
Schuko standard internally but, until recently, they exported
appliances to the Soviet Union with the Soviet standard plug
installed. Because the volumes of appliance exports to the Soviet
Union were large, the Soviet plug has found its way into use in
Eastern Europe as well.
and Outlet Requiring Plug Adapter #WA-7
used in the United Kingdom, Ireland, Cyprus, Malta, Malaysia and
plug has three prongs (two flat and one rectangular) that form a
triangle. British Standard BS 1363 requires use of a three-wire
grounded and fused plug for all connections to the power mains
(including class II, two-wire appliances). British power outlets
incorporate shutters on line and neutral contacts to prevent
someone from pushing a foreign object into the socket.
British domestic electrical system uses a ring main in the
building which is rated for 30 amps (5 amps for lighting rings).
Moreover, there is also a fusing in the plug; a cartridge fuse,
usually of 3 amps for small appliances like radios etc. and 13
amps for heavy duty appliances such as heaters. Almost everywhere
else in the world a spur main system is used. In this system each
wall socket, or group of sockets, has a fuse at the main
switchboard whereas the plug has none. So if you take some
foreign appliance to the UK, you can use an adaptor, but
technically it must incorporate the correct value fuse. Most
would have a 13 amps one, too big for the computer for example.
BS 1363 was published in 1962 and since that time it has
gradually replaced the earlier standard plugs and sockets (WA-10)
and Outlet Requiring Plug Adapter #WA-16
used in Australia, New Zealand, Papua New Guinea and Argentina)
plug has also a grounding pin and two flat prongs forming a
V-shape. There is an ungrounded version of this plug as well, the
#2 plug adapter with only two flat V-shaped prongs. Although the
above plug looks very similar to the one used in Israel (type H),
both plugs are not compatible. Australia’s standard
plug/socket system is described in SAA document AS 3112 and is
used in applications up to 10 amps. Although there are slight
differences, the Australian plug mates with the socket used in
the Peoples Republic of China (mainland China).
and Outlet Requiring Plug Adapter #WA-11A
almost exclusively in Switzerland and Liechtenstein)
has its own standard which is described in SEC 1011. This plug is
similar to #1 & #6, except that it has the addition of a
grounding pin. This connector system is rated for use in
applications up to 10 amps. Above 10 amps, equipment must be
either wired permanently to the electrical supply system with
appropriate branch circuit protection or connected to the mains
with an appropriate high power industrial connector.
and Outlet Requiring Plug Adapter #WA-20
almost exclusively in Denmark and Greenland)
Danish standard is described in Afsnit 107-2-D1. The plug is
similar to WA-9 except that it has a grounding pin instead of
grounding clips. The Danish socket will also accept either the
CEE 7/4 or CEE 7/7 plugs: however, there is no grounding
connection with these plugs because a male ground pin is required
on the plug. The correct plug must be used in Denmark for safety
reasons. A variation of this plug intended for use only on surge
protected computer circuits has been introduced. The current
rating on both plugs is 10 amps.
and Outlet Requiring Plug Adapter #WA-12A
almost exclusively in Italy and randomly found throughout North
Italian grounded plug/socket standard, CEI 23-16/VII, includes
two styles rated at 10 and 16 amps and differ in terms of contact
diameter and spacing. The plugs are similar to #1 & #6 except
that they are earthed by means of a centre grounding pin. Because
they can be inserted in either direction at random, they are
and Outlet Requiring Plug Adapter #WA-10L
almost exclusively in South Africa, Swaziland and Lesotho)
plug resembles the Indian WA-10 plug, but its pins are much
larger. WA-10L is rated at 15 amps. Although it is standard in
India, Sri Lanka, Nepal and Namibia, WA-10L is also used for
larger appliances. Some sockets over there can take both type
outline map below visualises the spread of the different plug types
used around the world. For easy reference, compatible plug types are
represented with the same colour.
do I need to use my appliances abroad ?
do not convert electricity. They simply allow a dual-voltage
appliance, a transformer or a converter from one country to be
plugged into the wall outlet of another country. The plug of a
Continental European appliance will not fit into an outlet in a
foreign country without an adapter.
and transformers both step up or down the voltage, but there is a
difference in use between them. Converters should be used only with
"electric" products. Electric products are simple heating
devices or have mechanical motors. Examples are hair dryers, steam
irons, shavers, toothbrushes or small fans. Converters are not
designed for "continuous duty" and should only be used for
short periods of time (1 to 2 hours). Additionally, most converters
can only be used for ungrounded appliances (2 pins on the plug).
Converters must be unplugged from the wall when not in use.
also step up or down the voltage, but they are more expensive than
converters and are used with "electronic" products.
Electronic products have a chip or circuit. Examples are radios, CD
or DVD players, shavers, camcorder battery rechargers, computers,
computer printers, fax machines, televisions and answering machines.
Transformers can also be used with electric appliances and may be
operated continually for many days. The advantage of converters,
however, is that they are lighter and less expensive.
are electronic devices and therefore they must be used with a
transformer, unless they are dual voltage. Fortunately, most laptop
battery chargers and AC adapters are dual voltage, so they can be
used with only a plug adapter for the country you will be visiting.
are sold in various sizes based on how much wattage they can support.
Therefore one must pay careful attention to the wattage ratings of
the appliances to be plugged into a transformer. The wattage rating
of the transformer must always be larger than the wattage rating of
the appliance to be plugged into it (plus a 25% buffer to allow for
heat build-up in the transformer or converter). When plugging
multiple items into a power strip, then into the transformer, you
must calculate the combined wattage of all appliances and the power
strip, then add an additional 25% to that total.
appliance’s voltage and wattage requirements are listed on the
manufacturer's label located on the back or at the bottom of the
appliance. In some cases, the voltage and amperage will be listed,
but not the wattage. If this is the case, simply multiply the voltage
by the amperage rating to find the wattage rating (e.g. 230 V * 1 A =
is a list that gives an idea what the wattage of common appliances
is. Use this as a guide only. Always check your appliance first !
watts: small, low-wattage appliances such as radios, CD players,
heating pads, and some televisions.
watts: larger radios, stereo consoles, electric blankets, sewing
machines, hand mixers, small fans and most TV sets.
– 2000 watts: dishwashers, most appliances that have heating
elements such as toasters, electric deep-frying pans, irons, and
only convert the voltage, not the frequency. The
difference in cycles may cause the motor in a 50 Hz appliance to
operate slightly faster when used on 60 Hz electricity. This cycle
difference will cause electric clocks and timing circuits to keep
incorrect time: European alarm clocks will run faster on 60 Hz
electricity and American clocks will lose some 10 minutes every hour
when used in Europe. However, most modern electronic equipment like
battery chargers, computers, printers, stereos, DVD players, etc. are
usually not affected by the difference in cycles and adjust
themselves accordingly the slower cycles.
can only “electric” appliances be used with a converter,
and not “electronic” ones ?
difference between a converter and a transformer lies in how the
device converts voltage current. Alternating current power is
supplied in alternating bursts that are in a shape called a "sine
wave". To reduce 230 V to 110 V, for example, a converter chops
off the sine waves in half, whereas a transformer alters the
amplitude of the waves. This is a critical difference because
electronic devices require a full sine wave for operation. This is
why they can only operate with a transformer. Electric appliances
function with either a full or a half sine wave, so they can be used
with either a converter or a transformer.
converter's "chopping" off of sine waves is a relatively
simple and compact function. The transformer's alteration of sine
waves is a relatively sophisticated function and requires more space.
As a result, transformers are generally larger, heavier and much more
expensive than converters.