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When 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 appearance.
At 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.
As 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 supply.
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 appliances
abroad.
Below is a brief outline of the
plugs and sockets used around the world in domestic environment.
The outline map below visualizes the spread of the different
plug types used around the world. For easy reference, compatible
plug types are represented with the same colour.
Look Up Table
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