NEMA Power Cords
NEMA plugs, or connectors, are more commonly known as standard American electrical
plugs, and are used throughout the United States and many places in Canada.
NEMA connectors adhere to the standards set by the National Electrical Manufacturers
Association, an American-based organization which formed in 1926 and is universally
recognized across the U.S. as a major authority of electrical codes and standards.
Virtually all of the electrical plugs and connectors used in the U.S. adhere
to NEMA codes, and NEMA's standard of regulations help to maintain consistency
and order between electrical manufacturers and consumers.
The two most common NEMA standard connectors are the 1-15P and the 5-15; these
are plugs with a body typically made of molded rubber and prongs made from
steel or brass with a zinc, tin, or nickel coating. The 1-15P is the older
of the two, as it has only two flat parallel prongs, one of which is the neutral
prong, the other a live conductor. Recent electrical codes have made it so
that one prong is slightly wider, ensuring its neutrality and, incidentally,
making the new 1-15P connectors incompatible with older outlets. 5-15 plugs
are more recent, and have the same flat parallel prongs with the addition of
a round grounding rod below both prongs; this rod makes for a safer connection
by grounding the device being plugged in before the connection is made live.
Both plugs have a maximum current capacity of 125 volts, although the 5-15 "3-pronged
plug" is generally used with higher-voltage appliances for safety purposes.
Other NEMA connectors carry different variations on these two common plugs,
with more or differently placed prongs and increasing voltage capacities. The
standard types run all the way up to L23, which is a twist-locking connector
and carries the highest voltage for NEMA connectors: 600 volts. The twist-locking
L series and most other connector types are used for industrial purposes, and
the types of connectors coincide with various types of use and voltage. For
example, some types of locking connectors are used in boats, where there is
often movement and it is important that power connection not be lost or exposed
where water damage could cause a short. The twist-lock cannot be pulled out
of its outlet unless it is twisted open.
NEMA standard connectors, while universal in much of North America, are not
standard worldwide. The most common connector in Europe is the Europlug, or
the European 2-pin, which is similar to the NEMA 1-15P two-prong except that
the Europlug's prongs are round and not flat. Other connectors used around
the world include the Old British Plug with three round pins (the third is
for grounding), the French 2-pin with a male grounding pin, the South African
3-pin, and so on. All together there are more than a dozen common standard
connector plugs in use worldwide, although adaptor kits are available. The
recent rise in the Europlug's use has consolidated many disparate European
standard plugs into one universal connector, but it remains to be seen whether
this trend will continue throughout the world anytime in the near future.