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Archive 1Archive 2

Separate?

Many of these sections could be expanded into their own articles including common useages, regions, histories etc. Should we consider seperating this article into many smaller articles which would be easier to expand? 48v 03:40, 11 July 2006 (UTC)

The article isn't really big enough to need it yet but when it becomes so just split out long sections and replace them with a shorter summary and a main article link. Plugwash 21:05, 11 July 2006 (UTC)

Weird image...

Is there a reason the GFCI pic is a line drawing? I thought we only used them for sex acts? 68.39.174.238 20:21, 10 October 2006 (UTC)

Feel free to replace it with a photo provided the photo shows all the relavent features reasonablly well. Plugwash 20:00, 11 October 2006 (UTC)

terminology

Perhaps a brief discussion about the meaning of words like "plug" "socket" "receptacle" "connector" etc. It seems different words are being used to describe similar things, and the same word used to describe different things. So, first off, these words need to be defined, and a standard usage needs to be adopted so as to not be so confusing. 143.127.3.10 21:08, 5 June 2007 (UTC)

Globalize tag?

In what way does this need a "worldwide view". As an article about a specific electrical code element, I fail to see how that tag is relevant. The intro notes that these plugs are used in countries other than the US. Pjbflynn 00:22, 19 June 2007 (UTC)

The beginning mentions other countries that use it, but the rest of the article only discusses the US and Canada.--Jorfer 23:55, 19 June 2007 (UTC)

like, NEMA10, eh???

"In Canada, the use of NEMA 10 devices was discontinued much earlier (if it was ever permitted at all), so NEMA 14 devices are more common there."

Um, so were they ever permitted? or were they not? It's got to be one or the other, eh? --carlb 05:24, 6 March 2007 (UTC)

FWIW, I don't remember ever seeing a NEMA 10 plug or receptacle (Montreal, QC). I remember from around the mid-late 1980's when the landlord of the apartment that I was living in did some electrical upgrades and one of them was adding a NEMA 14-50 plug/receptacle for the stove which was previously hard wired into the wall. --Aa456 00:33, 24 September 2007 (UTC)

Safety comparison

Could somebody who understands this stuff include a safety features section similar to a Schuko#Safety_features and Europlug#Design_considerations? And compare the NEMA std with Schuko, europlug and others? --Jirka6 (talk) 16:54, 31 March 2008 (UTC)

Afaict they don't really have any, if you partially insert an american plug you can easilly touch the live pins. I guess the americans think (rightly or wrongly) that the lower voltage means such features are not required. Plugwash (talk) 18:23, 22 January 2009 (UTC)

Long winded

My word, this article does babble on. One picture would truly be worth 1000 words - we could then condense the text to "NEMA connectors use different combinations of pin widths, orientation, and dimensions to furnish connectors that are unique to a particular voltage, current capacity, and grounding system" or words to that effect. Put on my to-do list, I'm sure I can redraw from CEC and NEMA to save a ton of space here. --Wtshymanski 17:46, 21 July 2006 (UTC)

Hear, hear! [But I can't help noticing that it's been nine months since you wrote that. What's keepin' ya?  :-) ] 24.6.66.193 19:23, 18 April 2007 (UTC)
Busted. But I've been fighting off the kibibytes and remodelling a bathroom...it's been a busy year. --Wtshymanski 21:46, 18 April 2007 (UTC)
Just remember: Black goes to black, white to white, and always use GFCIs ;-).
Atlant 12:12, 19 April 2007 (UTC)
Hear, hear! DIAGRAM PLEASE! Here's an example of a good NEMA diagram. I'd add one myself but someone will probably beat me up with a copyright bat. --Goodmanj (talk) 20:52, 16 June 2009 (UTC)

Given that the NEMA standard is available for free download, are the other links necessary? (Argument for: the NEMA link isn't a direct link; it requires that you agree with a simple license.)

Jordan Brown 08:13, 26 February 2007 (UTC)

Furthermore, it's a very large file that contains painstakingly intricate blueprint-style drawings intended for product designers. Simple, straightforward diagrams aimed at ordinary people would be preferable, such as the ones found here:
http://www.frentzandsons.com/Hardware%20References/twistlockplugandreceptacle.htm
http://www.frentzandsons.com/Hardware%20References/plugandreceptacleconfiguratio.htm
24.6.66.193 05:01, 21 April 2007 (UTC)

Bob Stein - VisiBone (talk) 18:00, 4 September 2009 (UTC) — I agree with the need for a comprehensive, basic diagram for users. Thanks, Jordan, for yours. Here's another great diagram that finally cleared up a lot of my confusion.

http://www.sheffield-pottery.com/Articles.asp?ID=127 (article with diagram)
http://www.sheffield-pottery.com/v/vspfiles/assets/images/nemaconnectors.jpg (diagram)

Here's Goodmanj's good diagram, copied from above (though missing NEMA 10):

http://www.nooutage.com/nema_configurations.htm (diagram and nomenclature)

NEMA 2-20 fitting NEMA 5-20 & 6-20?

I don't think that's correct. The pin orientation would allow it if the spacing was the same, but according to the standard, the pins in a NEMA 2-20 connector are farther apart (.844 in center to center) than the those in a NEMA 5-20 or NEMA 6-20 (.609 in center to center). Carolina wren (talk) 06:29, 28 May 2010 (UTC)

Python?

During my searching, I've seen "python", "python plug" and "python connector" mentioned multiple times. Are these NEMA connectors also called "python plugs"? That seemed kinda odd to me. 188.192.118.79 (talk) 03:23, 12 February 2010 (UTC)

Python is a brand name for a series of plugs and connectors (the female version of a plug you'd find on an extension cord for example) manufactured by Leviton. You attach them to the cord yourself. The name "python" probably comes from that they hinge open like clams and the two screws that hold the thing together look like fangs. --Marc Kupper|talk 06:59, 9 October 2010 (UTC)

1-15 Plug Picture

A_plug.jpg

The current picture for the 1-15 plug, A_plug.jpg (at right) - which lists itself as a "Type A" connector and not a NEMA 1-15P, does not appear to be a NEMA1-15P. I believe that NEMA plugs in this series all have circular holes in them to be grabbed by the socket. Can someone confirm? tonsofpcs (Talk) 02:41, 4 April 2011 (UTC)

Why do you believe that? The NEMA standard WD 1 is availble for free download. It says the holes in the ends of the blades are optional, but if present, have to meet specified dimensions. You can't have a receptacle that relies on an optional feature of a plug. --Wtshymanski (talk) 02:50, 4 April 2011 (UTC)

http://www.cpsc.gov/CPSCPUB/PUBS/099.pdf should be updated (this is the correct link) for the GFCI fct sheet. All I see is reflist2 and cant change it. —Preceding unsigned comment added by 198.169.188.226 (talk) 13:14, 20 May 2011 (UTC)

 Done Updated in the "Special safety features" section [1] --Tothwolf (talk) 02:55, 21 May 2011 (UTC)

Historicals

Lots of practical info here, but very little historical data or other social/soft stuff. Anyone care to add it in? —Preceding unsigned comment added by 67.81.164.24 (talk) 02:53, 24 October 2008 (UTC)

(years later) A perennial problem. Everybody has the current catalog and code book, nobody has any historical documents. It's like everythign was given to us by flying saucer. --Wtshymanski (talk) 16:39, 19 January 2012 (UTC)

Reversions on NEMA 10

@Mautby: Please don't edit war. If you want to discuss, please do so here.

  • The image you removed is hosted by Wikipedia and in fact is being put into Wikimedia commons. If you want to remove an image, please remove the other one, which is external. ANd I don't see it in the article at all anymore, actually.
  • In addition to the picture, you removed text which is relevant and does not appear elsewhere in the article.

I believe this provides a sound basis my restoration of material that you then reverted. Since the text I restored is well established, please gain consensus for removal before you pull it out again. Dovid (talk) 18:03, 18 November 2013 (UTC)

Neither of the above statements is true. The image of the obsolete socket was moved to a new section on obsolete devices. The text was also moved to that section, at the same time the broken link to the patent was replaced by a working one. Your unnecessary reversions have been undone. Mautby (talk) 19:06, 18 November 2013 (UTC)
I don't know what broken link you refer to. You removed two images and some text. One image was to And when I compared the original text to the moved text, it was close but incomplete. I checked the text that you removed. There are no broken links, all three images work, and it includes slightly different language on the obsolete design (AU ref standard, implied possibility of it preceding the patent). The differences are not bigm and I could live without them, but I saw no reason to. The only reason there could be considered any duplication is due to the fact that the obsolete section was restored, without discussion. The only discussion took place in the other article, but as pointed out there by another editor, NEMA discussions do not belong there, they belong here. So it should have been at least mentioned in the talk page here with a reference to the other article talk, and additional time allowed for NEMA editors if any to chime in. IN all honesty, it isn't worth my effort to deal with this acrimony, which is a typical issue at WP, and its loss. Dovid (talk) 17:21, 19 November 2013 (UTC)
Frankly, that is the sort of sloppy response which typifies careless editing; it is quite difficult to discern what you are trying to say! Your first statement is clear I don't know what broken link you refer to., but the reason you say it is far from clear, as I clearly referred to "the broken link to the patent". The link that you reinstated was this: http://patimg1.uspto.gov/.piw?Docid=1179728&idkey=NONE
The link which works, but you removed, is this: http://pdfpiw.uspto.gov/.piw?Docid=1179728&idkey=NONE&homeurl=http%3A%252F%252Fpatft.uspto.gov%252Fnetahtml%252FPTO%252Fpatimg.htm
I put great value on accuracy, it really is important to check that edits work before saving them, and again immediately afterwards so that inadvertent errors (which we all make) can be corrected there and then. Mautby (talk) 18:18, 19 November 2013 (UTC)
Mea culpa on sloppy talk page editing. Happens. Looks like something typical of my hyperactive trackpad, though I'm surely responsible for my own texts.
The broken link you refer to is part of a ref. The text you removed includes an in-line image. Since you didn't mention that it was a ref, I didn't in the refs, and the only "link" I could find in the contended main text was the inline image. So I guess you might say we were both sloppy in our descriptions on the talk page.
The broken ref predated all my edits. On the 17th I was searching for a working replacement, found one, and seeing that it was public domain, decided that the image of the patent would be even better than just a fixed patent link alone. By the time I got around to editing to incorporate that, you had beaten me to the punch with your updated ref by a few hours. When I went to the NEMA 10 section to add the image in, I found it had been recently removed. That's when I reverted and added the patent image in. So serendipity had us both working on the patent at the same time, and that kicked this whole thing off, ironically. Have a good laugh. Dovid (talk) 02:47, 22 November 2013 (UTC)
Thank you Dovid, I guess that lays it to rest. Best wishes. Mautby (talk) 23:52, 22 November 2013 (UTC)

"Pole" undefined

The article suddenly introduces the word "pole" without ever defining it. The word is heavily used in one section, and then mentioned again in one other section. This is all very confusing to a non-expert reader. Could somebody find a clear definition of "pole", as used in this article? Reify-tech (talk) 12:47, 20 December 2013 (UTC)

Good catch. The term as used for electrical devices does not have its own WP article but redirects to and is defined in Switch:

The number of "poles" is the number of separate circuits which are controlled by a switch. For example, a "2‑pole" switch has two separate identical sets of contacts controlled by the same knob.

I dislike using the term "circuit" for purposes here. For single-phase power wiring the live and neutral contact sets together supply one "circuit", while the ground contacts are not part of any circuit that is supposed to be seeing appreciable current. So the number of contact pairs doesn't match the number of circuits here. But something close to this explanation should work. Could we use the word "connections" instead? Something like

Connector types are characterized by the number of "poles". This is the number of separate connections that are made or broken when mating or unmating a connector pair and which are expected to carry current in normal operation. In counting the number of poles, live and neutral contacts are included, but ground contacts are not.

I think it's acceptable, but I'm not overjoyed with it. Refinements, anyone? Jeh (talk) 19:33, 20 December 2013 (UTC)
You may wish to consider that ground would not be counted as a pole in international terminology, a NEMA 5-15 grounded would be described as "two pole (2p) and earth". Mautby (talk) 20:15, 20 December 2013 (UTC)
Isn't that what it says above? I did originally have that wrong, but I corrected it almost immediately. Do you think the point needs to be expressed more than twice? Do you have other suggestions for improvement?
How about this:

Connector types are distinguished by the number, shape, and physical arrangement of mating contacts. In the standards, the number of contacts is expressed as the number of "poles" plus, if present, a grounding (earthing) contact. Live and neutral contacts are included in the number of poles, but grounding contacts are not. Thus the common North American "three-prong grounded" plug, the NEMA 5-15, is described as "two pole (2p) and earth".

Jeh (talk) 21:06, 20 December 2013 (UTC)
Jeh, I seem to remember that I started my comment, addressed to your original wording In counting the number of poles, live, neutral, and ground contacts are all included., and was then called away before I saved it, by the time I did it appears that you had corrected it anyway! You might want to change live to phase, remember both phase and neutral are classed as live contacts. ref: Electrical Inspection Manual, 2011 Edition, Noel Williams & Jeffrey S Sargent, Jones & Bartlett Publishers, 2012, p.249 Mautby (talk) 03:41, 21 December 2013 (UTC)
As I said, I did orginally have that wrong, but I corrected it. Didn't you see an "edit conflict" when you saved? Don't you use "preview"? ... oh well.
Re. "phase", I wonder if that term is really as well known as it needs to be, to convey the correct meaning here. Would you like to suggest a wording of your own? Jeh (talk) 04:05, 21 December 2013 (UTC)
Use hot, line or phase, whichever you prefer, they are all used interchangeably in the article already. But please, do not introduce the misuse of "live", its use in the article at present is correct, why spoil it? Mautby (talk) 12:31, 21 December 2013 (UTC)

Relationship to ANSI?

How does NEMA relate to ANSI, from a standards perspective? Do their standards overlap, or do the organizations cooperate with each other? Why do some connectors have ANSI numbers such as "ANSI C73 13"? Why is the dimensional standard called ANSI/NEMA WD–6? 3dimen (talk) 14:33, 5 June 2013 (UTC)

So NEMA is a private association of electrical equipment manufacturers that develops standards related to electrical devices. ANSI is a private organization that accredits standards developed by other organizations. So NEMA developed their standard "WD-6" for electrical connectors, and ANSI accredited the standard as being reasonable and useful. It's written as ANSI/NEMA WD-6 so that people know it's been approved by ANSI. The "ANSI C73" designation is an older standard for electrical connectors. This standard was obsolesced by the WD-6 standard. I can't find a good reference, but I think what happened was prior to 1980 or, ANSI would refer to standards based on their internal review committee numbers, as opposed to the trade group that developed the standards, so the ANSI C73 is just the standard reviewed by the C73 review group, which happened to be electrical connectors. The WD-6 standard is the new one, and should be used for all new design, engineering, and acquisitions. However, it appears that references to the "ANSI C73" in the US Code of Federal Regulations; so people keep referring to it even though it's obsolete because there may be a legal requirement to do so. Bosef1 (talk) 01:06, 7 July 2014 (UTC)

I've added a section on additional and related standards for the NEMA connectors. It's kinda US centric right now, but I guess all the NEMA stuff is, what with it being a national standard and all. The only standards listed are UL 498 for actual plug construction and Fed Spec W-C-596 for "military" grade connectors. I added this mostly so I could find the Fed Spec number again. I don't know much about the UL 498 standard, so any additional input would be appreciated. Bosef1 (talk) 01:13, 7 July 2014 (UTC)

Name change

Over a year ago there was discussion about shrinking the AC power plugs and sockets article by moving many of the family-specific details to family-specific articles.

Subsequently this was done for the British connectors, resulting in what is now named AC power plugs and sockets: British and related types.

Although I was one of the strong proponents of this reorg, I subsequently got busy with real work (since I'm self-employed that's a good thing). Now however I'd like to pick this up again. But unlike the previously attempted page split, I want to be sure first that no one objects. So...

I would like to proceed with this effort here. Accordingly, this article would be renamed to AC power plugs and sockets: NEMA and related types. This article would become the place for comprehensive coverage of these connectors, and the NEMA section of AC power plugs and sockets would be reduced to include only introductory-level information about the most common types and all material from there that's not already here, would be copied here.

Is there any objection? Jeh (talk) 06:19, 23 September 2015 (UTC)

Jeh I think that this would be a good rationalizing move and go a long way towards achieving conformity. FF-UK (talk) 06:33, 23 September 2015 (UTC)
Last day for protests! Going once... going twice... Jeh (talk) 22:11, 27 September 2015 (UTC)

Are 5-15 connectors allowed on 20A circuits in the USA

if they are why do people bother with the 5-20 T slot in kitchens?

if they are not why is the 5-20 T slot (which also allows a normal domestic plug to be connected to a 20A circuit) allowed? Plugwash 11:51, 15 September 2006 (UTC)

Yes, 5-15 receptacles are allowed on 20 amp circuits. For example, most North American GFCI outlets use 5-15 pinning but are rated at "20A pass-through".
I'm not sure I understand the second half of your question, but I'll make some observations: You'd certainly want kitchen convenience outlets to accommodate 5-15 plugs because most of the loads in the North American world have that connector, even pretty hefty electric cooking loads like table-top broilers and big coffee makers. On the other hand, accommodating a 5-20 plug is a nice feature and cues the user that the circuit is a 20A circuit, even if there are very few domestic loads with a 5-20 plug. (I've only seen 5-20 plugs in industrial environments.) If I were to rewire my kitchen again, I'd probably install 5-20R T-slots for that reason.
Atlant 13:45, 15 September 2006 (UTC)
5-15 receptacles are allowed on 20A circuits as long as there is more than one receptacle on the circuit. In some jurisdictions, a 5-15 duplex counts as more than one receptacle, in others, not. Where I live, if you have just one receptacle on a circuit, it has to be a "single" receptacle, and it has to be a 5-20R. A 5-20R on a 15A circuit is not allowed anywhere.Yak99 00:14, 23 April 2007 (UTC)yak99
How are 5-20R receptacles able to carry more current than a 5-15R given that the dimensions of the "hot" blade (if im reading the article correctly) are identical ?
Type Designation Introduction Neutral Width Hot blade Width Remarks
2 pin unpolorised NEMA 1-15 19?? 6.35 mm 6.35 mm 1/4 inch neutral blade
2 pin polorised NEMA 1-15 1948 7.938 mm 6.35 mm 5/16 inch neutral blade
3 pin grounded NEMA 5–15 1927 (mandatory 1962) 6.35 mm 6.35 mm Only polorised with 3 pin plugs
3 pin polorised NEMA 5–15 1948 (mandatory 1974) 7.938 mm 6.35 mm
3 pin 20 Amp NEMA 5–20 19?? ? 6.35 mm Most recent standard -Transition ongoing.

82.132.139.217 (talk) 18:55, 22 December 2011 (UTC)

For a variety of reasons, a connector's rating is usually far, far less than what it can actually safely carry. Jeh (talk) 21:33, 27 September 2015 (UTC)
How are 5-20R receptacles able to carry more current than a 5-15R given that the dimensions of the "hot" blade (if im reading the article correctly) are identical ? It isn't that they can carry more, but that it restricts their use. You can put many (I don't know the exact number) of 5-15R on a 20A circuit, assuming that they won't all run at the full 15A. I believe you can only put one 5-20 (but maybe duplex is fine) on a 20A circuit, with no other loads on the circuit. (I didn't look it up, so don't wire your house based on that.) The kitchen rules also restrict the outlets on a circuit, as kitchen loads (toaster, microwave, coffee maker) can run close to 15A. (There is now a free NEC online reading site if you want to see what it says.) Gah4 (talk) 21:03, 15 September 2016 (UTC)

why do air conditioners get special treatment?

are they in some way more dangerous than other large portable loads (such as portable heaters) or is it just a case of them gaining more attention because there are in more common use. —The preceding unsigned comment was added by Plugwash (talk • contribs) .

Probably because they're inherently wet during operation (from condensate) and often wet from precipitation.
Atlant 23:04, 15 September 2006 (UTC)
It seems that they are. For one, they are the rare portable home use device using more than 1800W (for 5-15R) or 2400W (for 5-20R). But also, being not so portable when installed, some like to nail the power cord to the wall. There is a new restriction on air conditioner power cords that requires leakage current detection in the cable. Gah4 (talk) 21:09, 15 September 2016 (UTC)

Ground fault circuit interrupter (GFCI) receptacles

Re NEMA connector#Ground fault circuit interrupter (GFCI) receptacles[citation needed]. The requirement(s) for their use, especially in bathrooms, is (are) to be found in the national building codes of Canada and the US, in the provincial and state building codes as well as in the city and municipal building codes. The rub is that these codes do not appear to be available for a gratis consultation but must be ordered on line for the payment of serious money. Try to google National Building Code of Canada & see what it gets you. have fun... Peter Horn 20:44, 10 June 2009 (UTC)

There is now an online (no download) free site for reading the US NEC (from NFPA).[1] I suspect it might be newer than 2009. (You have to get a free account.) I don't know about Canada. Gah4 (talk) 21:16, 15 September 2016 (UTC)
  1. ^ "Free Access to: 2017 edition of NFPA 70". www.nfpa.org. NFPA. Retrieved 15 September 2016.

NEMA 1 Voltage rating?

IN the Article it states "All NEMA 1 devices are two-wire non-grounding devices (hot-neutral) rated for 125 V maximum". These connectors (and others similarly described) are used in many countries where the mains voltage (phase to neutral)is 220/240V [1] so either these countries are using them dangerously outside of their rating or some wiki entries are incorrect. Can anybody comment? — Preceding unsigned comment added by Lightening Rod (talk • contribs) 20:45, 24 March 2013 (UTC)

NEMA seems to be a US organization, and mostly affects US and Canada. Each country decides what to do to keep its citizens safe. Many in the US would say that 220V is unsafe for home use, though it reduces the needed copper in wiring. Type A plugs are probably a little less safe, in that it is easier to contact live pins than with many European plugs, but I don't know that they should be unsafe otherwise. The breakdown voltage of plugs and wire insulation is plenty high enough, but contact with 220V is much harder on people. Most professional electricians seem to work (carefully) on live 120V systems, but not so many on higher voltages. Much of the NEMA design is to keep from intermixing plugs within the NEMA system. Gah4 (talk) 19:42, 15 September 2016 (UTC)
I suppose one question is what unsafe conditions you might consider. The main effect of higher voltage is dielectric breakdown, where the voltage is high enough to start conducting through the plastic. From a table[2] of plastic properties, plastics can hold off from 10 to 170 kv/mm, with nylon (a popular plug material) at 25kV/mm. Add some safety margin, and one mm of plastic will keep you safe against maybe 10kV, or 1/40 of a mm for 250V. In a real plug, you will likely be at least 1mm of plastic away from 240V. The main unsafe condition with NEMA 1 plugs is that it is possible to contact live pins when the plug is partly inserted. Contacting 240V is more dangerous than 120V, but both are considered unsafe to contact. European plugs are better at keeping users away from contacting live pins. Gah4 (talk) 07:50, 17 September 2016 (UTC)
  1. ^ http://en.wikipedia.org/wiki/Mains_electricity_by_country
  2. ^ "Electrical Properties of Plastic Materials" (PDF). www.professionalplastics.com/. professional plastics. Retrieved 17 September 2016.

6-20

"The 20 A plug has the neutral pin rotated 90 degrees, and the 6-20R receptacle may have a T-shaped hot hole, to accept both 6-15P and 6-20P plugs"

i didn't think american 240V wiring had a neutral so both holes are hot. Plugwash 02:13, 24 June 2006 (UTC)

Nearly all wiring has a neutral, without neutral, there is nothing reliable to refrence the 240 volts to. 48v 03:40, 11 July 2006 (UTC)
Ok i could have phrased that better, in US wiring 240V basically means both hots so in a socket that supplies only 240V (e.g. the nema 6 series we are discussing here) there won't be a neutral. Plugwash 20:43, 11 July 2006 (UTC)
So I presume that by 'both hots' you mean that there are two seperate 110 volt legs which makes plenty of sense. My question is this: what are the 110v legs refrenced to if there is not neutral?
There is a neutral in the supply system just not at the socket, relative to neutral the two hots are the same magnitude but 180 degrees out of phase with each other, so equipment that needs 120V is connected between one hot and neutral (and uses a 1- or 5- series plug), equipment that needs 240V is connected between both hots and not connected to the neutral (and uses a 2- or 6- series plug) equipment that needs both (e.g. cookers, clothes driers etc) is connected to both the hots and the neutral (and uses a 10- or 14 series plug). Plugwash 23:24, 11 July 2006 (UTC)
Ahh. That makes much more sense. Thanks for explaining! 48v 23:45, 11 July 2006 (UTC)
Actually, that's not entirely accurate. There's no neutral in a 240V circuit. Two points of confusion: (1) the 240V are not relative to anything other than _each other_: they are 240V (RMS) apart from each other. (2) There is, however, a ground that is earth potential: one of the "hot" conductors is 120V "above" the ground and the other is 120V "below". The ground is not used in an ordinary 240V circuit except for safety. Some circuits, like a typical electric clothes dryer, require both 120V and 240V circuits; they will add a neutral line. To get their 240V circuit, they use only the two hot wires; to get their 120V, they use one of the hots and the neutral. So what's the difference between neutral and ground, you may ask? That's actually a good question, as the neutral is connected to the ground back at the main panel. The difference is that neutral is designed to carry the return current in a circuit, whereas the ground is not designed to carry current. In fact, in some places (unfinished basements, bathrooms, etc.) you are required to install a GFCI breaker, which will break the circuit as soon as it senses any current on the ground line. Fool4jesus (talk) 14:52, 26 February 2012 (UTC)
By the way GFCIs don't sense current on the ground, but instead the differential current between hot and neutral. That detects current shunted to the ground wire, or through you to a cement floor. (Cement floors are fairly good conductors.) Gah4 (talk) 22:47, 15 September 2016 (UTC)
Correct. In fact, last time I checked, NEC allows the installation of a GFCI outlet in older installations where there is no ground wire, and of course it requires one anyplace where GFCI would normally be required (basically near water or laid-on-the-ground concrete floors). And then you can connect other outlets with ground pins downstream of the GFCI, again with no actual ground connection. The GFCI provides the protection that's implied by the presence of the ground pin, although by different means. Jeh (talk) 02:14, 16 September 2016 (UTC)
Yes. You have to label them "No Equipment Ground" in addition to the usual required "GFCI Protected". All GFCI that I know of come with a little sticker for the latter, but not the former. And if you chain outlets, you aren't supposed to pass the ground along. Gah4 (talk) 14:06, 16 September 2016 (UTC)
240v could easily be live-to-neutral in a commercial or industrial environment. This explanation is beyond the purview of this talk page, but I suggest looking at mains distribution articles (and wye and delta). 69.205.240.64 (talk) —Preceding undated comment added 02:33, 4 April 2011 (UTC).

I believe the figure that shows all the receptacle layouts ("NEMA simplified pins.svg") is incorrect with respect to the 6-20. It's shown identical to the 5-20, which is not correct. — Preceding unsigned comment added by Pgf (talk • contribs) 20:30, 19 February 2013 (UTC)

In the case of the 10-30 and 10-50, previously commonly used for electric dryers and electric ranges, respectively, it was usual for low current loads, such as timers and even light bulbs, to connect phase to ground. I believe that the 14-30 and 14-50 are now required, with separate ground and neutral. As far as I know, and I don't see anything in the NEC[1] regarding the wiring of 6-15 or 6-20. As far as I know, it is not allowed to use the grounding pin of 6-15 and 6-20 as neutral, in which case appliances should work with either split phase or 240V and neutral. The latter would be rare, and likely not code, in residential settings. In industry, and some apartments and dormitories, it is more usual to have two phases of a 120/208 wye circuit. Gah4 (talk) 22:47, 15 September 2016 (UTC)

The 240V configuration at a 6-15 or 6-20 receptacle could involve several different permutations of voltage to ground depending upon the supply type. In the typical residential or small business environment, the supply will be the common 120/240V single-phase type, so each "hot" leg will be at 120V to ground, and no neutral is provided at the receptacle. As mentioned above, in commercial environments with a 120/208V three-phase wye supply, the same receptacle can be found connected across two phases to provide 208V, still with 120V to ground on each leg. In the case of a 240V corner-grounded delta supply (rare these days, but still some around), you could end up with one side of the receptacle at ground potential and the other at 240V to ground, or with both sides at 240V to ground depending upon the phases used. Also becoming rarer and no longer installed in most areas but still around is the 4-wire delta derived by taking a 240V delta secondary and grounding the center-point of one winding. Depending upon the phases chosen for the connection, a 6-15/6-20 receptacle on such a system may end up with each side at 120V to ground, or with one side at 120V and the other at 208V. 47.35.10.200 (talk) 20:30, 26 September 2016 (UTC)

  1. ^ "Free Access to: 2017 edition of NFPA 70". www.nfpa.org. NFPA. Retrieved 15 September 2016.

Upside down 5-15

The NECA_130 Draft says (available here: http://apps.necanet.org/files/NECA_130_draft.pdf) it is acceptable to install the receptacle with the ground pin up OR down so long as it is consistent for the facility.

I'd question the rationale in the paragraph:

"It is customary in the U.S. to install 5-15 and 5-20 receptacles with the ground pin down. This is to ensure that a loose cord remains grounded even if its two prongs no longer contact the line voltage. As a safety measure, however, many receptacles are now installed "upside down" (with the ground pin up.) In the case of a metal object falling onto a dislodged cord, the foreign object is less likely to straddle two conductors, possibly avoiding a short circuit."

As I understand the practice, the goal is to make it less likely that a metal object falling between the plug and socket will touch the live blade without first touching the ground pin. A short circuit, which would trip the circuit breaker, is a more desirable outcome than a live bare metal object that someone might come in contact with. --agr 11:28, 14 June 2006 (UTC)

In every diagram of NEMA connectors I've seen, the ground pin is on the top. The NEMA standard document (available in PDF format here: http://www.nema.org/stds/wd6.cfm) shows the ground pin on top. Leviton has a nice diagram of all the pin configurations showing ground pins on top here: http://www.leviton.com/sections/techsupp/nema.htm

I agree that the reason for having the ground pin on top is to prevent conductive objects dropped between the plug and receptacle from contacting a live pin. The loose cord explanation for having the ground pin on the bottom doesn't entirely make sense, since the ground pin's primary purpose is to ground any internal shorts and trip the circuit breaker. With the plug loose enough so the live pins no longer contact, there will be no reason to protect against internal shorts, since there will be no internal voltage. The ground pin is longer so it is the first pin to contact, so any internal shorts will go directly to ground upon insertion. I believe, in all seriousness, that the reason it is customary in the U.S. to install these receptacles with the ground pin down is because people like to see the "smiley face". I don't know if the NEC specifies one way or the other. --Rich 02:35, 20 July 2006 (UTC)

I think a part of the reason the connectors are installed "ground pin down" is the mnemonic attraction: the earthed safety conductor faces the earth. I also wonder if there was a hang-over effect from the earlier ungrounded recepticles. That is, was it conventional to install these with neutral leftwards and hot rightwards? That would certainly explain keeping that convention when 5-15 connectors came around.
Atlant 11:35, 20 July 2006 (UTC)
If there is a reason for installing them ground down, I think it must be anthropomorphic. They look like faces. I'll admit that's why I prefer to install them that way. Rich is correct that the NEC does not specify.Yak99 00:10, 23 April 2007 (UTC)yak99
Could it be that the reason for the grounding pin down is that most (at least the ones that I have seen) is that the cord would be sticking up if the pin/hole was up instead of down. I looked at the cord for my computer and the cord comes out of the bottom of the plug if the grounding pin is at the bottom. Aa456 05:04, 15 October 2007 (UTC)

I'm not sure why, but it's common (at least in the Midwest) see the ground down in residential wiring, and the ground up in commercial wiring. Jayscore (talk) 02:05, 10 December 2007 (UTC)

I think the reason may be ergonomic. Try grabbing a plug with the ground pin up and typically it's not as comfortable as with the ground pin down and your thumb on the (typically) flat top of the plug.154.5.124.154 (talk) 20:37, 21 July 2009 (UTC)

The article says that it is customary to install these with the ground pin down, but all the pictures show the ground pin up. Either the pictures or the text ought to be changed. —Preceding unsigned comment added by 67.142.162.28 (talk) 23:28, 11 July 2010 (UTC)

According to longtime electricians in my family, a big reason for putting the ground on the bottom is so it acts as a brace to help keep the plug from tilting downward & exposing the blades, which matches my experience growing up in a house with ground-up outlets. Try experimenting with an unplugged power strip and IME you'll find the same: it's much easier to tilt it away from the ground plug than vice-versa. —Xyzzy☥the☥Avatar 08:29, 29 September 2013 (UTC)

My experience is that it's historical. Older construction tends to have the ground pin down; newer, ground pin up. But I was in one house where they'd installed almost everything one way but used the opposite to denote outlets connected to wall switches. Jeh (talk) 21:28, 27 September 2015 (UTC)
I don't see it one way or the other in the NEC.[1]

The referenced NECA "standard" cited for a preferred NEMA 5-15R orientation is a voluntary installation guideline from a contractor's association not an authoritative source. The NECA is the "National Electrical Contractors Association" The NEC, the "National Electrical Code" is published by the "National Fire Protection Association". Specific versions of the NEC have been incorporated by reference into the building code of each of the states of the United States by legislation that may also exclude or modify specific sections. No revision of the National Electrical Code has ever cited a preferred or required orientation for the installation of NEMA 5-15R receptacles. The rationale commonly given for preferring a ground pin superior orientation is a scenario where a metal cover plate that loses its screw(s) and falls on exposed contacts might balance on the (round) ground pin and never contact the ungrounded power contact. It is more probable that it will eventually slip and contact the ungrounded power conductor. An unsecured cover plate is already prohibited by the NEC because it presents a shock hazard, and any hot material created during the failure of either the receptacle or any wire splices in the box will not be contained and may ignite nearby combustible materials. PolychromePlatypus 17:16, 24 September 2016 (UTC)

NECA 130-2010 (which is, I believe, the current version) clearly states, in several places, that it is "An American National Standard" . It also states that its use is voluntary, but, of course, there is nothing unusual about a standard which is not mandated, very few are! FF-UK (talk) 20:55, 26 September 2016 (UTC)

The use of "Edison" to describe NEMA 5-15 plugs and receptacles appears to have begun relatively recently as a shorthand description in use by mainland Chinese equipment suppliers. If this is an accurate understanding, then it would be better if Wikipedia did not perpetuate an ill-informed foreign language colloquialism. The name "Edison" was not historically used for 2-prong (later NEMA 2) or 3-prong (NEMA 5) 125v plugs and receptacles in North America. The only related historical use of "Edison" was the threaded "Edison" base fuse, which was identical to the threaded base on single filament lamps of 150w or less. PolychromePlatypus 17:16, 24 September 2016 (UTC)

"Hubbell" was never used for NEMA 5 connectors. This appears to have arisen from a poorly edited web based source. It was common to refer to the circular contact pattern locking connectors patented and made only by the Hubbell Co. as "Hubbell" connectors through the 1960's even though there were multiple sources by that time. By the 1970's these were referred to as "twist-locks", not "Hubbells", which then referred only to high cost, very high current round shell connectors with machined pin and socket contacts used for boat marinas, mainframe computers, and other niche markets. The NEMA L5, L6, etc. standard designations now cover the specific types originally referred to as "Hubbells". PolychromePlatypus 17:16, 24 September 2016 (UTC) — Preceding unsigned comment added by PolychromePlatypus (talk • contribs)

There is still nothing in the NEC which specifies ground up or ground down, because it's not considered an important issue. In fact, there's nothing in the NEC to say that receptacles can't be mounted sideways (i.e. ground left or ground right), which I understand is actually the norm in some cities. 47.35.10.200 (talk) 20
23, 26 September 2016 (UTC)
There are restrictions on receptacles that are face up, though, such as countertops. Other than that, I don't see anything about orientation. Gah4 (talk) 20:39, 26 September 2016 (UTC)
  1. ^ "Free Access to: 2017 edition of NFPA 70". www.nfpa.org. NFPA. Retrieved 15 September 2016.

nema 2 series dangerous.

it was claimed in domestic ac power plugs and sockets in content now moved to unusual and obsolete plugs and sockets that the 2- series connectors were dangerous. I can't see any danger in using them with 240V class 2 equipment other than the slight risk of connecting a 240V appliance to 120V (which would most likely just result in the appliance not working) would anyone like to comment on this? Plugwash 17:20, 15 September 2006 (UTC)

Well, not having a ground pin could be considered dangerous. For residential use in 120VAC countries, there isn't much need for ungrounded 240VAC appliances. If you did have such an appliance, you could still put a grounding plug on it, though that does hint that the appliance is grounded. If I had something with that plug, I wouldn't be any more worried than with any other ungrounded appliance. Gah4 (talk) 22:44, 26 September 2016 (UTC)

Unsourced

6-15R and 6-20R receptacles are usually manufactured on the same assembly line as "Industrial" or "Commercial" grade 5-15R and 5-20R receptacles, with all 4 receptacles sharing the same "triple wipe" T contacts behind the varying faceplates. The faceplate bonded onto the receptacle determines the final configuration of the receptacle.[citation needed] I removed this unsourced statement, which mostly applies to manufacturing details. It was reverted explaining And as for "uncited" it is hardly a controversial or implausible claim. I suppose it isn't implausible, but that doesn't seem a convincing reason for not needing a citation. I could smash apart a bunch of outlets, and then learn how the different companies built them. I am not sure how many it would take to be usual. One picture of a smashed open outlet could show that it sometimes occurs. Gah4 (talk) 19:55, 15 September 2016 (UTC)

It is completely plausible that it is "usual" because keeping as many components as possible common between the two types is obviously an economical way to do it. The vast majority of the cost in making injection-molded plastic pieces, or stamped metal pieces, etc., is in setup - making the mold or the tool and die.
A related claim that I think would demand a source would be that the sockets were deliberately designed with the goal of making as many components common between the two as possible - as opposed to the manufacturers figuring out how to do that after the design was standardized.
n.b.: Technically you are within your rights to "challenge and remove" any unsourced material, however obvious it is to some editors... but you have to ask yourself: Are you really improving the encyclopedia thereby? Jeh (talk) 20:09, 15 September 2016 (UTC)
I might have thought that 5-15 was enough more common, and the extra metal just enough, that they wouldn't do it for that. The less common 5-20, 6-15, and 6-20 maybe with common metal parts. The statement says usually, a little stronger than sometimes. At the time I thought it was an improvement, however small. A picture showing the insides would at least get to sometimes, but we don't even have that. A picture, in addition, would be an improvement to the rest of the article. I suspect that I only have residential grade. Gah4 (talk) 20:53, 15 September 2016 (UTC)
Anyone with an actual source, or picture of a smashed open receptacle showing the inner construction. (Though the latter could be considered OR, it is fine to me.) Gah4 (talk) 23:09, 26 September 2016 (UTC)
Still no source? Gah4 (talk) 21:07, 6 October 2016 (UTC)

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Ground or Neutral

Although there are several non-grounding device types in the NEMA standards, only three of them are in widespread use today. I thought the third pin on 10-30 and 10-50 was a ground pin, not a neutral pin, but maybe the difference isn't so obvious. I believe it connects to the metal frame on dryers and ranges, but is also used with 120V timers and lights. Though some ranges switch 120V across a heating element in the lowest power mode. Gah4 (talk) 07:25, 17 September 2016 (UTC)

The third pin on those obsolescent plugs is connected to the neutral conductor running back to the breaker box. It is only "grounded" inasmuch as the neutral is connected to ground at the breaker box. There is no dedicated "safety ground" in these older connectors, which is why they are now deprecated. Reify-tech (talk) 16:21, 17 February 2017 (UTC)

Hyphen, en dash, em dash

Hi @Carnby just curious where you find an official NEMA document saying that its an en dash? Not saying you're wrong, just that I wasn't able to find any official looking indication either way, on their site or otherwise (google).

Did you end up asking at the village pump? because I had already (previously) asked at the Tea House. At least that was the concensus for the many instances within the body of the article. Whether it also needs the literal "it is actually an en dash" is the other question.

tea house question on hyphen vs em or en dash — Preceding unsigned comment added by Mucm (talk • contribs) 21:58, 29 January 2016 (UTC)

Carnby (talk · contribs) Mucm (talk · contribs) Here is the Village Pump discussion. The only reference seems to be a scanned PDF. It is impossible to tell from it whether they were hyphens or en dashes in the original (and, of course, no way to know if that particular graphic artist's choices reflected the "official" documents). I'll bet these standards were originally prepared, way back when, on a typewriter that had only a hyphen, and the engineers who actually wrote them couldn't care less.
Although there is no official closure I believe the VP discussion can be summed up the same way as the one at the TH, namely "leave 'em as hyphens, it's better for the reader if browser inpage search works, rather than being typographically correct, not that we know what's correct anyway". I have deleted the "they're really en dashes" text as a) we have no reference for that claim and b) most readers aren't likely aware of what an "en dash" even is, and this article is about NEMA connectors, not typography.
I actually think hyphens are more correct for model or type designations anyway. I find nothing at MOS:HYPHEN or MOS:DASH specifically one way or the other, but it seems to me that "5-15R" or "B-29" or "RS-232" is much more like a single term that happens to include a hyphen than it is like two independent words that are being somewhat linked. (You'll notice that the latter two articles use hyphens.) Certainly I find no rationale within MOS:DASH for using an en dash, but in MOS:HYPHEN I find "In hyphenated personal names: John Lennard-Jones.". Use of a hyphen in a model or type designation seems to me to be close to that, certainly closer than any of the reasons expressed for using an en dash. Jeh (talk) 00:31, 31 January 2016 (UTC)
I agree, a hyphen is preferable over a dash in this context, because it links the two or more parts of a model or type designation (e.g. FOO-123-BAR). There is no implication of contrast or separation, which would require a dash. Reify-tech (talk) 16:29, 17 February 2017 (UTC)

Redundant terminology section

@FF-UK: and @JimmiCheddar:, please justify your continued insistence in reverting my well-sourced edit. The relevant information—that the IEC calls receptacles "socket-outlets" and blade terminals "pins"—is entirely retained, complete with sources. The rest of the terminology section uses loaded language that infers that the common, accepted North American terminology is not so-called "normal English". As this is an article about a subject that is entirely North American in scope such language is entirely inappropriate, and runs counter to the Wikipedia Manual of Style with respect to the use of national varieties of English. Such terminology differences ought to be glossed over, rather than an entire glossary being added. Given the only relevant information in the terminology section has been otherwise incorporated in the nomenclature section there is no reason whatsoever to keep the terminology section. This article is about NEMA plugs and receptacles, not the IEC. CplDHicks (talk) 23:19, 17 February 2017 (UTC)

@Jeh: discuss. CplDHicks (talk) 05:21, 18 February 2017 (UTC)
Per WP:BRD, after you're reverted, YOU are supposed to start discussion. I don't agree with your changes. Please justify them. It is up to you to justify changes to the status quo. Jeh (talk) 05:40, 18 February 2017 (UTC)
And btw, I'm watching this page, so no need to ping me. Thanks. Jeh (talk) 05:41, 18 February 2017 (UTC)
I started this discussion prior to your revert, so that's why I pinged you. You obviously weren't paying much attention. You wanted it, here it is. Discuss. CplDHicks (talk) 05:46, 18 February 2017 (UTC)

1. This is the English Language version of WP, it is not the North American WP.

2. This version of WP is used by English speakers from all around the world (English is the World language in greatest use).

3. I agree that it is entirely appropriate for this article to be written in American English.

4. Both the US (via ANSI) and Canada (via the Standards Council of Canada) are full members of the IEC.

5. It is normal for IEC members to align their standards, where possible, to IEC standards. This does not mean adopting everything in an IEC standard, for instance the overarching IEC standard on "Plugs and socket outlets for household and similar purposes", IEC 60884, does not include any standard sheets for particular styles, but does define general principles and terminology. NEMA is one of the few exceptions to this norm. It is not my place to comment on whether the deviations of NEMA are a good or bad thing, but it is important to assist non-North American readers to understand the differences, and for North Americans to be aware of international standards.

The original edit in which I inserted the Terminology section involved replacing a number of inappropriate uses of the IEC term "socket" with the NEMA term "receptacle" and a number of inappropriate uses of "outlet" where receptacle is the correct term (in North American terminology "outlet" refers to a physical location, "receptacle" to the actual socket). Not the actions of an editor who does not respect the WP policies on varieties of English! I also corrected a number of glaring inaccuracies in the text, including several claims that some connectors were "single pole"! It was while performing these edits that I realised that an explanatory addition was required. I considered adding something to the "Nomenclature" section but as this is mainly devoted to explaining the method of identifying individual connector types, chose to add the new section instead (similar terminology sections exist in other mains connector articles). The language used in the Terminology section is not "loaded" as claimed by CplDHicks, it is a straightforward statement of fact and is most certainly NOT "redundant". FF-UK (talk) 18:43, 18 February 2017 (UTC)

The additional information in the terminology section is both accurate and useful. There is no justification in the position taken by CplDHicks. JimmiCheddar (talk) 22:53, 18 February 2017 (UTC)
Agree with FF-UK and JimmiCheddar. Jeh (talk) 00:47, 19 February 2017 (UTC)
Having now reviewed the text in question, I have to agree that the Terminology section serves a worthwhile purpose, and has decent references. I have great respect for FF-UK and his extensive work on this and related articles, and his clear explanations of the reasoning behind his editorial choices. I agree with the 5 points he makes above, which are carefully explained with worldwide readers' thorough understanding of this technology as a goal. Before this reworking, the article was a sad jumble of inconsistent, ill-defined jargon, and I don't want to see it descend into such a mess again. Reify-tech (talk) 04:22, 19 February 2017 (UTC)

Added a section about NEMA connectors in the laboratory

I added something about NEMA connectors in the lab, specifically about heating mantles. While it doesn't exactly affect everyone I considered it a sufficiently important concept to include. Many labs, including teaching labs, have two or more ordinary-looking receptacles. Some will be variable voltage, some will not. There isn't a consistent color code.

It's exceedingly common for students, even after being warned about it, to plug equipment into the variable-voltage receptacle and complain that their equipment doesn't work. Heating mantles are generally reserved for students with more experience, because the consequences of putting those into the wrong receptacle are much worse than a stirrer failing to stir.

It's an example, I suppose, of the reason why there are so many connectors in the first place -- what can go wrong will go wrong, and since variable-voltage circuits in labs don't have special connectors, things go wrong.

Roches (talk) 22:11, 6 February 2014 (UTC)

This would seem to be about lab practice rather than NEMA connectors, I can see nothing specific to NEMA connectors and do not believe that it belongs in this article. Mautby (talk) 22:23, 6 February 2014 (UTC)
Okay. The article has several highly specific sections about, for example, stage lighting. The error I described is very common, and by no means restricted to one lab or my personal experience. The article includes several examples of plugs designed to prevent dangerous situations. I thought it might be of interest because this is an example of a situation that could be avoided with a specific receptacle. But I agree it would be more appropriate in a different article. Roches (talk) 23:49, 6 February 2014 (UTC)
This could probably be done as a footnote for special purpose receptacles instead of a dedicated subsection. For that fact, one could also footnote the (mis)use of receptacles for freestanding lamps on dimmer-controlled circuits (which unless I'm mistaken, is actually against the NEC in the US, but they are seen "in the wild" from time to time).
On a somewhat related note, would it be useful if I begin taking photos of some of the other special purpose receptacles described in NEMA connector#Color code? I think I have examples of most of those laying around that I can snap photos of. "Hospital grade" can also refer to plugs and cord-mounted sockets. --Tothwolf (talk) 07:36, 7 February 2014 (UTC)
To Roches: There is also an article about laboratory safety, which would be an excellent place to add your points about variable-voltage receptacles and heating mantles. There already is a subsection on electrical safety, and your additions would be very appropriate there. Reify-tech (talk) 14:43, 18 February 2017 (UTC)
In these comments at least there seems to be a consensus that the article is better without the laboratory section, and perhaps better without sections about specialized uses. So, I have no objection to removing that content. Roches (talk) 16:57, 21 February 2017 (UTC)
Yes, this article is already quite long and detailed, whereas the laboratory safety article is still C-class and needs expansion. More importantly, readers who would be interested in the topic are much more likely to read the lab safety article than they are likely to wade through a lot of material here that may not be directly relevant to their interests. There currently is no mention of heating mantles there, and the electrical section is vestigial in length and coverage. I suggest that you bring up your suggestions there for discussion, and add any useful material to there. A Wikilink would be useful here, once there is content to point to. Cheers! Reify-tech (talk) 17:17, 21 February 2017 (UTC)
I notice that the lab safety content here is gone. It can be recovered from the History of this article, or just recreated from scratch. What matters is that it should be added to the laboratory safety article, where it will be more useful and likely to be seen by interested readers. Reify-tech (talk) 17:52, 21 February 2017 (UTC)

Frequency?

Shouldn't it say something somewhere about how many hertz these plugs are generally used with? Especially since this is not the same as other plugs (I'm pretty sure NEMA connector are usually used with 60 hertz, in contrast with the 50 hertz of European models). I don't feel that I really know enough about this though to edit the article. 209.176.79.34 (talk) 18:04, 8 January 2008 (UTC)

Whoops, wasn't signed in. The above is me. Crito2161 (talk) 18:05, 8 January 2008 (UTC)
I wouldn't argue too strenuously, but my feeling is that it doesn't need to be in this article. The frequencies used in different markets are discussed in mains electricity, which is linked at the top of this article. Here is my basic argument against inclusion: For each connector type, we talk about the voltage and current it's used for. We do this for two reasons: (1) The connectors are deliberately different, so that you cannot connect devices in a hazardous way. Plugging a 120 V appliance into a 240 outlet would be hazardous, and a home in North America (for example) can have both 120 V and 240 V outlets, so preventing this confusion is important. (2) The connectors actually have to be designed differently, depending on the current they handle. The 50 A receptacle has to be made more robust than a 15 A receptacle, so that it doesn't catch fire. But frequency has neither of these concerns. If you're in a 60 Hz country, you're getting 60 Hz electricity no matter what outlet you plug into. And any 60 Hz receptacle would be physically capable of handling 50 Hz power, or vice-versa—we're not talking about RF or microwave frequencies where it's a critical design parameter. So basically, the situation is that NEMA connectors are used in the same places that the electricity is 60 Hz, but neither fact has anything directly to do with the other. -- Coneslayer (talk) 18:56, 8 January 2008 (UTC)
Some transformers desgined for 60Hz won't work properly at 50Hz, but usually not the other way around. As I understand it, Japan has both 50Hz and 60Hz in one country, but that is rare. There are some industrial uses for 400Hz, and there might be plugs and outlets designed for that. 400Hz is sometimes used in aviation, where the transformers are smaller and lighter. Pretty much, NEMA connectors are used for 60Hz. Gah4 (talk) 19:15, 15 September 2016 (UTC)
The NEMA standard does, however, specify that "Configurations utilized on alternating current systems,[sic for the superfluous comma] are limited to 50 or 60 Hertz, unless otherwise specified.... The electrical ratings of the configurations in these standards are AC and DC, unless specifically stated 'AC' or 'DC'." (Introduction, p. iv). Since the standard does directly address frequency, perhaps the article should take account of this. 72.76.2.163 (talk) 06:17, 26 August 2013 (UTC)
In Canadian homes the only 220 or 240 V outlets are those for the electric laundry dryer and the kitchen stove (range) which both require a spcial oulet (not the same for them both) so the possibilety to plug a 110 V appliance in a 240 V outlet are all but nill. Peter Horn 20:30, 10 June 2009 (UTC)
No air conditioners in Canada? Window air conditioners often run 20A/240V. Switches often have a lower rating for DC, as there is no zero cross to stop any arcing that might start. Series wound motors will run on either AC or DC, and are often labeled that way. I don't know where you would find a DC outlet to plug one in, though. Gah4 (talk) 21:05, 26 June 2017 (UTC)

Compatibility

Can American NEMA plugs be plugged int Japanese outlets (and vice versa) & the appliance run without any problems? 68.14.147.200 (talk) 04:49, 10 May 2008 (UTC)

Afaict (i'm not american or japanese so this is from information I have picked up on line) the answer is usually yes but there are a few potential issues
1: a lot of japanese sockets will only accept the plugs with two narrow blades, not the ones with a wider blade used for polarisation:
2: the japanese voltage is a bit lower which may cause problems for some applicances
3: half of japan uses 50hz, some american appliances may not like the lower frequency
4: if you are planning to sell something the safety standards are different which could potentially bring up legal issues. This isn't really an issue if it's only for your own use though.
-- Plugwash (talk) 18:40, 22 January 2009 (UTC)

Many small devices now are rated 100-240V 50/60Hz, so should be fine in Japan. It used to be that, for example, audio equipment sold for world (other than US and Canada) use would have a multitap transformer that allowed for 100V, 120V, 220V, 240V. Maybe they still do. Gah4 (talk) 21:09, 26 June 2017 (UTC)

non-standard

I reverted the removal mentioning the popular use of a non NEMA plug. It seems worth mentioning, otherwise readers will assume that the NEMA plug is to be used. It would, however, be nice to link to a description (not here) about the actual plug, its uses, and otherwise. Gah4 (talk) 05:56, 26 June 2017 (UTC)

The removal was correct. There is already a link to AC power plugs and sockets, the article which includes California connectors, under "See also", but I have added a clarification to that. FF-UK (talk) 07:26, 26 June 2017 (UTC)
I have restored one of the two mentions. Although I firmly agree with "articles should be about their subject" (a line I've used often in opposing various cases of topic creep), it is not necessary to be so rigorous about it as to diminish the value of the article. Sometimes a subject is better defined by including a bit of description of things that it doesn't include, but which a reader might logically assume it includes. A mere mention of a non-NEMA connector for applications that a reader might think would be covered by a NEMA connector is not out of place here, even in the article body. It's not as if we're featuring photographs, etc., of these. Jeh (talk) 08:08, 26 June 2017 (UTC)
I agree that mentioning the existence of the "California Standard" connectors is quite appropriate and helpful to readers of this article. The article AC power plugs and sockets doesn't contain any mention of the California connectors, nor does a Wikipedia-wide search, so there is very little content to point to. The best course of action might be to create a new article and Wikilink it to other related articles. Reify-tech (talk) 18:24, 26 June 2017 (UTC)
Here's one forum thread I found with some seemingly good info. Of course we can't use it directly but it may provide pointers as to what to look for. Jeh (talk) 19:18, 26 June 2017 (UTC)
Here [2] (linked from the one above) is a page with some discussion, pictures, and links. One page indicates that they are often used in the Hollywood film industry, possibly being better when dragged around on the ground. Also that the metal shield adds protection against the arc from hot disconnect. A Hubbell catalog page describing one (of the six) is: [3]. Six connectors should be enough for their own page. Gah4 (talk) 19:52, 26 June 2017 (UTC)
Happy to accept the consensus view, and sincere apologies for misidentifying the location of the California entry, it is actually in Industrial and multiphase power plugs and sockets I have corrected the article. FF-UK (talk) 20:02, 26 June 2017 (UTC)
Thanks all. It seems that there are actually six different plugs, the first three are 50A at 125V, 250V, and 480V. At $67, I don't expect to run out and buy many of them. It does sound like they are used in RV and boating applications, so not only industrial users. The real question, is why NEMA doesn't standardize them? (That is, copy the standard in the same way that IEC does.) Gah4 (talk) 20:53, 26 June 2017 (UTC)
If there is a NEMA standard 50 amp connector, why does the "California standard" type still exist? Inertia in the movie business? And is there a "standard document" that gives the dimensions, pinouts, etec. for them? --21:03, 26 June 2017 (UTC)
If you'll look at the forum thread I linked above, you'll see some reasons offered - the "California" connectors have some advantages. Jeh (talk) 15:47, 27 June 2017 (UTC)
As of now, searching Wikipedia for "California Standard", "... connector", "... plug", "... socket", etc. turns up nothing helpful. Could somebody set up appropriate redirects or dab pages to point to the relevant subsection of Industrial and multiphase power plugs and sockets? Until FF-UK mentioned it above, I had no idea that there was any coverage at all, and the average Wikipedia reader won't find this information if it doesn't show up in the search results. Reify-tech (talk) 16:21, 27 June 2017 (UTC)

There's your definition

See WP:TALKNEW, "Make the heading clear and specific as to the article topic discussed". I have moved the content of this section to "Terminology section", a title which reflects the subject itself. FF-UK (talk) 14:49, 18 October 2017 (UTC)

Terminology choices , the general reader, and WP:COMMONNAME

If the term "receptacle" for a common electrical outlet is so unfamiliar to the general reader -- and (I TELL YOU THREE TIMES) I agree that it is -- why insist on using it?

The article AC power plugs and sockets doesn't slavishly stick to the IEV-recommended term "socket-outlet". Yes, it does mention it in the terminology section but most uses that are in the article body are direct quotes from IEC documents. In far more instances (about 435 to 35) it simply calls them "sockets".

Why don't we adopt a similar strategy here?

Just because the NEMA documents say "receptacle"? Of course we can't ignore that term completely: it's the origin of the "R" suffix used in NEMA's designations. But we have ample cause to not use it much beyond that, and to say "socket" instead.

Consider WP:COMMONNAME. The birth certificate of the 42nd President of the United States reads "William Jefferson Clinton", but that's not what his bio article is called. I know, COMMONNAME is about article titles, but the principle informs article content too.

Consider MOS:COMMONALITY: "Universally used terms are often preferable to less widely distributed terms, especially in article titles" (but it does not say "only in article titles").

And if that is not enough, there is the principle that Wikipedia is written for the general reader. I agree that nowhere in the world are we likely to find general readers, or even specialists in the field, who often use the term "receptacle" in this context. I doubt that very many people, even specialists in the field, who even hear or read the term routinely.

So why not follow MOS:COMMONALITY and just call them "sockets"?

Of course we'd need a bit of explanation at the beginning - close to what's already in the "terminology and nomenclature" section, just turned on its head: ~"We use the common term 'socket' here, but NEMA calls them 'receptacles' and the IEC calls them 'socket-outlets'".

Then the reader who skips the "Terminology and nomenclature" section (as, let's face it, most do) will be seeing only familiar terms through most of the article. Jeh (talk) 02:22, 15 November 2017 (UTC)

Some years ago, I started a discussion about ethernet hub which should be called an ethernet repeater. The claim, though, is that hub is the WP:COMMONNAME and so the article should have that name. I suspect that most people know the name receptacle, at least when they see it written, but maybe think it is too long. I might be that hub being shorter than repeater is the case for ethernet. But the article title is NEMA connector. Should it be NEMA plugs and sockets? Gah4 (talk) 23:05, 17 November 2017 (UTC)
WP:SINGULAR discourages the use of plurals in article titles. Jeh (talk) 23:59, 17 November 2017 (UTC)
OK, NEMA plug and socket. Sounds funny, though. Gah4 (talk) 01:04, 18 November 2017 (UTC)
There is an exception the names of classes of objects. Seems to me that applies here. Gah4 (talk) 01:07, 18 November 2017 (UTC)
This isn't the focus of what I was writing here. I'm not talking about changing the name of the article. I'm talking about using the term "socket" routinely within the article, instead of the very-little-used but NEMA-standard term "receptacle." If you want to change the article name that discussion should go in another section. Jeh (talk) 01:43, 18 November 2017 (UTC)
Jeh I suppose that it will not surprise you to know that I agree with your suggestion re: "socket". FF-UK (talk) 18:05, 24 November 2017 (UTC)
Then why did you revise the article to routinely, even rigorously, use the term "receptacle"? Jeh (talk) 18:46, 24 November 2017 (UTC)
I didn't! Immediately before my major tidy up of the article on 7th February 2017 there were 132 occurrences of "receptacle", 6 of "socket", and 26 of "outlet", afterwards the corresponding numbers were 148, 4 and 16. To have chosen to replace occurrences of "receptacle" with "socket" with no discussion would have been wrong. FF-UK (talk) 21:16, 24 November 2017 (UTC)
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