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NEMA standards North American plugs and sockets |
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NEMA standards North American plugs and sockets |
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NEMA* standards are used in the US, Canada and Mexico. Comparable
flat blade plugs are used in Japan, various
Caribbean islands, parts of South America and some Southeast Asian
countries
* National Electrical Manufacturers Association (U.S.A.) |
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Related
galleries: locking devices dual Amp / Volt types classic types heavy duty types |
| Nomenclature Receptacle is used in American English rather than socket, but for the sake of unambiguity socket is preferred here. In North America different names and abbreviations are used. Neutral (N) is indicated as W which corresponds to the white wire; the black wire is 'Hot' (L)*. Equipment earth is indicated as Ground. Three phase L1, L2, L3 is in North America indicated as: X, Y, Z. * Occasionally a single phase hot connection is indicated as X. The following pages give additional information about US plugs: (1) History of US flat blade plugs, with emphasis on the role of Harvey Hubbell. (2) Logos and notes on history of manufacturers of material shown on North American pages. |
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| 1 | Duplex,
grounded socket
rated at 15A - 125V. The model corresponds to NEMA 5-15R (NEMA codes are explained below).
Slots for flat
blades may have
a different width. See plug no. 6 for explanation. Manufacturer: Cooper
Electric Supply, New Jersey U.S. |
| 2, 3 |
Tamper
Resistant NEMA
5-15 socket.
Hot and W slots have shutters. From November 2013 new and
renovated residential housings in the U.S. and
Canada
have to
be equipped with tamper resistant sockets. Simultaneous plugging in
both power blades pushes the shutter aside. Manufacturer: Pass &
Seymour (part of Legrand Group). {DH} |
| 4 | 15A - 125V
grounded
duplex socket (NEMA 5-15R), with ground fault circuit interrupter
(GFCI). This feature evaluates the current difference between line and
neutral and interrupts the flow of electricity when a sudden difference
is measured. Manufacturer: Leviton. |
| 5 | 15A - 125V
(NEMA 1-15P)
plug (top) and
connector
(bottom). For safety reasons, extensions
(indicated by green arrows) prevent the insertion of a grounded, 3 pole
plug in an non-grounded connector. The plug has brass blades of equal
width. Manufacturer: Eagle Electric
(plug). |
| 6 | A
difference in
width between line (hot) and neutral (W) blade changes an
essentially non-polarized NEMA 1-15
plug
into a polarized type. Manufacturer: Leviton. {DH}. |
| 7, 8 note |
Grounded
15A - 125V plug (NEMA 5-15P). The
position of the U-shaped earth pin results in a polarized plug; hot
and neutral are irreversible. The earth pin is 4 mm longer than the W
and X (hot) blades. This safety measure ensures that grounding is
already
effective before power pins make contact. The round base plate with pins can be fixed in eight positions with 45º rotational steps. Image nos 7 and 8 show five of eight positions. The plug has a side cord entry (downwards in plug no. 7). Without the possibility to adapt cord entry orientation it would be impossible to use two of these plugs in a dual socket (socket nos 1, 2 and 4). Orientations 8b and 8d are also useful when a socket has been mounted horizontally rather than vertically. {DH} The plug has a WE logo, indicating that it has been made in China by Weico (Asia) Industries Ltd. Very similar industrial grade 15A-125V (NEMA 5-15P) and 20A-250V (NEMA 6-20P) angle straight blade plugs, and 15A-125V (NEMA L5-15P) angle locking plugs are made also by Leviton Manufacturing Co. Inc. Plugs have the same eight different cord orientations. See respectively 5266-CA, 5466-CA and 4720-CA in Leviton catalog for details. Source of information: Cornell Wright. |
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| 9, 10 | NEMA 5-15R socket with isolated ground, also known as clean earth. It has two, separate earth connections – one is connected to the earth pin contacts of the outlets (green wire), and the other connects socket fixing screws to the general building earth. The green wire is connected to an earth reference bar. Read more about clean earth at the page on uncommon British sockets. The green dot indicated that it is a hospital grade socket (see no. 11 for details). Manufacturer: Leviton. {DH} |
| 11 | Hospital
grade NEMA 5-15 plug, which means that (i) blades are usually solid
instead of folded metal, (ii) the blades are normally nickel-plated,
and (iii) the plug
includes a cable retention device or strain relief to prevent any
stress to the plug's internal connections. Many hospitals prefer that
the plugs be clear so that internal connections can be
inspected visually, but this not an obligation. Hospital grade devices
are marked with a green dot (see inset top right). {DH} Manufacturer: Ching Cheng Wire Materials, Taiwan. |
| 12, 13 | Leviton Wetguard 5-15R (15A-125V)
connector (image no. 12) and 6-15P (15A-250V)* plug (image no. 13).
Wetguard®
watertight straight blade devices are engineered to IP66 and IP67
standards. Manufacturer: Leviton in Melville NY, USA. {FSE} * Find more U.S. 250 Volt device at the dual Amp / Volt page. |
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| 14 | Duplex 15A - 125V grounded power strip and an adapter plug with light, indicating when power is on. The top of the adapter has a single grounded outlet. The indicator light can also be used as a night light. Manufacturers: Leviton (power strip) and Woods Industries (adapter plug with indicator light) . |
| 15 | Multi-plug
for
three,
grounded 15A - 125V plugs. Manufacturer: Eagle. |
| 16 | Multi-plug for six, grounded 15A plugs. This device has to be used in a duplex socket (the 'standard' configuration, see no. 1) for providing sufficient stability. No brand name; made in China. |
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| 17 | Not earthed 15A-125V (NEMA 1-15R) socket; a nearly 'classic' model. From November 1973 all new outlets must have an earth contact (NEMA 5-15R). NEMA 1-15R is still available, but for repair use only. Manufacturer: Pass & Seymour / Legrand. {DH} |
| 18 | NEMA 1-15 plug-in
switch tap. Manufacturer: General
Electric (USA). |
| 19 | Multi-plug
for two
blade 15 A plugs (125V). The lower example is a swivel type device,
that can be tilted over 180 degrees. Both plugs are protected against
attempts to insert plugs with a ground pin; see image no. 5 for
comparable protection system. |
| 20 | Besides
US, Canada
and
Japan flat blade plugs are also used in many other countries.
The reliability of plugs in some Latin American and Asian countries is
occasionally doubtful. The image shows two examples. Top: Chinese made 15A molded flat blade plug. Bottom: Peruvian 15A "mini" connector. The Chinese plug is the only plug in the museum that fits in the mini-connector. The blades of standard US plugs are too wide and too thick. Unlikely that plug and connector comply with the U.S. safety standards. Note that plug and connector were (and still are?) used in countries that have a 220 Volt network. {PO} |
| The
variety in plug and
socket standards is unsurpassed The National Electrical Manufacturers Association (NEMA, USA) has set standards for configurations that differ depending on current rating (15, 20, 30, 50 or 60 A) and electrical potential (nominal 125, 208, 250, 277, 480 or 600 V)*. This has resulted in more than 35 different straight blade configurations (various grounding systems included). The system rules out accidental intermating of devices and related risks. * 480 and 600 V are three-phase only. The page on three-phase transformers explains the source of the other voltages. NEMA codes Codes consist of two numbers followed by R (receptacle) or P (plug). The first number indicates a class, second number refers to current. Class defines voltage, single, split- or three-phase, and grounded or non-grounded. Locking devices have a code preceded by an L For example NEMA 5-15R stands for a class 5 (125 Volt, grounded) socket. Plugs and sockets in Japan Also Japan uses flat blade plugs and sockets, in part comparable to NEMA types; they are shown on a separate page. |
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Locking devices Besides flat blade plugs and sockets NEMA has also defined locking devices. Japan has developed a deviant locking system. Click here for US locking devices. |
Dual Amperage /
Voltage types Series of sockets exist that can be used for more than one type of plug. Plugs can differ with respect to amperage and/or voltage. Click here for dual types. |
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