Talk:Industrial and multiphase power plugs and sockets

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Reyrolle plugs and connectors?[edit]

These were in use here in New Zealand until they were banned in 1990, normally they were 3 phase 400V Delta, with a scraping earth connection on the metallic body of the plug/socket combo, I remember as an industrial electrician getting a good tingle off of these plugs when plugging them in or unplugging them. Trumpy (talk) 09:45, 12 June 2017 (UTC)

NEMA 10 & 14 connectors[edit]

NEMA 10 & 14 connectors are used in neither industrial settings nor for multiphase power, and as such don't belong in this article. I had copied the information from the sections on this page to AC power plugs and sockets. However, a particular user has taken issue with this.

So, User:FF-UK, care to explain how you've come to believe NEMA 10 & 14 connectors are "industrial and multiphase"? Please, enlighten us all. CplDHicks (talk) 18:03, 23 July 2016 (UTC)

There are two issues here.
The first is the inappropriate decision to place additional information here: AC_power_plugs_and_sockets#North_American_and_IEC_60906-2 wherein is stated that: "A brief description of some common NEMA standards appears below. A more comprehensive list, with more detail, appears in the NEMA connector article." The general article does not need further detail on NEMA.
The second is the removal of content which has been present for more than 10 years in this article without first discussing it. I am neutral on this change, but there is a need to give other editors an opportunity to comment. There is no urgency in this!
FF-UK (talk) 19:50, 23 July 2016 (UTC)
The first issue you have is puzzling to say the least, considering the "AC power plugs and sockets" article already has subsections about the 14-30 and 14-50 connectors. And of course it does, because it's "about mains power connection devices used in domestic and light commercial environments". As this article already states, 14-30 and 14-50 plugs and receptacles are used for domestic clothes dryers and ranges (and they're slowly becoming more popular in home garages for use with electric vehicle service equipment). So that's the first issue I have with keeping the NEMA 10 and 14 subsections here: this article is about "industrial and multiphase power plugs and sockets" and the NEMA 10 and 14 designs are most commonly for domestic, residential uses.
Your second point, that this has been in this article for 10 years, is irrelevant: all it means is it has been wrong for 10 years. CplDHicks (talk) 20:54, 23 July 2016 (UTC)

Does two phase power count as multiphase? Because the article talks about 2 phase configurations. Does office use count as industrial use? Because the photo of the twist lock socket is probably a picture of a wall socket in an office environment. NEMA-14 is used in large copy machines. I suspect for the molded right angle low profile. Robert.Harker (talk) 21:23, 23 July 2016 (UTC)

I think there's a lot of confusion about what is meant by "125/250V", and it has to do with how North American homes (and many small businesses) are typically supplied with electricity. Homes are fed from a center tapped 240 V transformer, giving a "split-phase electric power". Three lines are fed to the home: a (grounded) neutral and two "hot". Essentially two halves of the 240 V are fed separately from the transformer to the home's main distribution panel; each "hot" is only 120 V with respect to the neutral, but they're still 240 V from each other.
The NEMA 10 and NEMA 14 plugs and receptacles are meant to be wired to use a combination of one of the 120 V hot-to-neutral halves and the 240 V hot-to-hot. The controls and other electronics (incl. the dryer's drum motor) of a clothes dryer or range will use one of the 120 V hot-to-neutral connections, while the heating elements will see the full hot-to-hot 240 V potential difference. Remember, the two hots are coming from opposite ends of the same transformer secondary.
NEMA 10 and 14 plugs can be connected to two of the three legs of a 208Y/120 source. They will still have a 120 V difference from one leg to neutral, but 208 V from one leg to another. Generally this won't damage a dryer or range, since the controls (and the dryer motor) will still get the 120 V it's looking for. The heating element will only receive 208 V instead of 240 V, so there is a commensurate reduction in performance. You might think this is "two-phase", but it's not: each leg has a different phase relative to neutral, but there is one (constant) phase difference from one leg to another. NEMA 10 and 14 connectors are for two voltage connections, not two phases. If you connected all three legs of a three-phase power source to a NEMA 14-30R receptacle (with no neutral) and plugged a clothes dryer with a NEMA 14-30P plug the dryer would not work. NEMA 10 and 14 connectors are explicitly meant for the connection of two 'hot' legs and a neutral (and in the case of NEMA 14, a ground). That's why neither one is a "multiphase" connector...
CplDHicks (talk) 23:43, 23 July 2016 (UTC)
The two 'hots' described are, as a result of locating the neutral at the mid point, 180 degrees apart in phase. This means there are two phases, therefore they are multi-phase. Denying this is completely illogical.
As there is a main article addressing NEMA connectors, that is the article which needs the complete information. Please refer to AC_power_plugs_and_sockets#British_and_compatible_standards as a good example of a concise summary of information which is fully dealt with in a separate main article. The summary of NEMA plugs and sockets was somewhat overblown before the additional information was added. The addition was quite unnecessary.
FF-UK (talk) 16:45, 24 July 2016 (UTC)
Quoted verbatim from "Split-phase electric power" [bold is my emphasis]: "A transformer supplying a three-wire distribution system has a single-phase input (primary) winding. The output (secondary) winding is center-tapped and the center tap connected to a grounded neutral. As shown in Fig. 1. either end to center has half the voltage of end-to-end. Fig. 2 illustrates the phasor diagram of the output voltages for a split-phase transformer. Since the two phasors do not define a unique direction of rotation for a revolving magnetic field, a split single-phase is not a two-phase system." If you connect a load between the two 'hots' the resultant is a single phase at 240 V.
Furthermore, copied verbatim from "Single-phase electric power": "No arrangement of transformers can convert a single-phase load into a balanced load on a polyphase system. A single-phase load may be powered from a three-phase distribution system either by connection between a phase and neutral or by connecting the load between two phases. The load device must be designed for the voltage in each case." If you connect a load between two of the three 'hots' on a 208Y/120 three-phase system the resultant is a single phase at 208 V.
Look, maybe these graphs will help you to understand: 240 V, 208 V.
Let's sort this page out before "AC power plugs and sockets"; whether or not you feel there is too much information on typical household NEMA connectors at that page is irrelevant to this page. I copied the paragraphs from this page to that page simply because this page has more information about them than that one does, even though they don't belong on this page at all. Again: NEMA 10 and 14 connectors are neither "industrial" nor are they meant for polyphase loads therefore they do not belong on this page. (NEMA 15, 16, 17, 18, 19 and 20 connectors look very similar to 14 and are meant for polyphase connections.)
CplDHicks (talk) 20:43, 24 July 2016 (UTC)
If something is split, then it is no longer single. If there are more than one, then the prefix "multi" is valid. As I said above, denying this is completely illogical.
What ends up in this article should be a result of consensus. As of now, that has not been achieved, and unless it is the status-quo should remain.
There is a small amount of information on NEMA 10 and 14 connectors in this article which is not in the main NEMA article, although the additions are mostly unreferenced. Perhaps such information should be added to the main article? There is no justification for adding further information to the overview of NEMA connectors in AC power plugs and sockets.
FF-UK (talk) 22:23, 24 July 2016 (UTC)
For the last time: the voltage is split from a single phase. Even the "Split-phase electric power" article begins with, "A split-phase or single-phase three-wire system is a type of single-phase electric power distribution." Arguing to the contrary is nonsense.
In order to put this argument to bed I went to the source. From ANSI/NEMA WD 6-2016, pp. 42-44, 49-53, and the chart on p. 143: type '10' and '14' devices are for 125/250 volts SINGLE-PHASE. As such I am going to rewrite the relevant subsections of this article. What ends up in this article must be a result of well-sourced material, and to include the current subsections describing NEMA 10 and 14 devices in an article titled "Industrial and multiphase power plugs and sockets" is blatantly incorrect because with absolutely incontrovertible proof from NEMA's own standard they single-phase connectors and, as the article already explains, they're most commonly used in homes for clothes dryers and kitchen ranges.
If you revert my changes again, which at this point would be running a fool's errand trying to argue from your own original research that NEMA's standards are incorrect, I must warn you I will have to report you to administrators for edit warring. Furthermore I will remind you that you do not own this article, nor do you own "AC power plugs and sockets".
CplDHicks (talk) 01:32, 25 July 2016 (UTC)

Taking a step back from this, it occurs to me that part of the problem is the term "multiphase" in the title. The NEMA connectors in contention are the only connectors referred to which are neither single-phase or three-phase. An appropriate solution would probably be to rename the article "Industrial and three-phase power plugs and sockets". I would also point out that the title includes the word "and" and in no way implies that all connectors mentioned are industrial. This is demonstrated by the inclusion of a number of three-phase connectors which are commonly used for domestic applications such as stoves in those countries where it is normal to provide three-phase service to domestic premises. As for edit warring, I would point out that the editor claiming ownership and indulging in edit warring is the editor who is unwilling to seek consensus following the original edit being challenged! FF-UK (talk) 09:38, 25 July 2016 (UTC)

I understand that the title of the article includes the word "and" and does not imply that all of the connectors mentioned are industrial, but, for what feels like the millionth time (and for the absolute last time): NEMA 10 and 14 devices are single-phase, residential devices. Ergo, they don't belong here at all.
As for edit warring and issues of "ownership", I looked through your contributions: you have a clear history of reverting changes to this article, "AC power plugs and sockets", "Mains electricity", "Mains electricity by country", "AC power plugs and sockets: British and related types", "NEMA connectors" and "IEC 60320". You describe yourself on your user page as "An Electrical Engineer with a particular interest in electrical safety issues and electrical mains connectors." Obviously these articles are central to your personal interests and expertise, and you've made considerable contributions to them, but you're also very clearly exhibiting an attitude of "ownership" over them. When I removed the NEMA 10 and 14 subsections it took you less than an hour to revert my edit, and whilst I explained in my edit summary "removed NEMA 10 and NEMA 14 sections, as they are neither industrial nor polyphase connector types" your edit summary was a wholly inadequate "This is the appropriate place for the information." I will remind you that "A reversion is a complete rejection of the work of another editor and if the reversion is not adequately supported then the reverted editor may find it difficult to assume good faith." (see Wikipedia:Reverting#Explain reverts)
I can only surmise you presumed my edit was in bad faith, that I was blanking entire subsections of this article for no good reason, despite my (totally, completely, 100% correct) justification. I found it difficult to assume your revert was in good faith due to your brusque edit summary and, given all the other evidence of "ownership" behaviour, I find it difficult to assume your appeal for "consensus" is in good faith and not merely an appeal for your approval.
Keep in mind that despite your having professional qualifications and a self-professed interest in the subject other people are probably making edits in good faith. I'm not out to "ruin" the article, I merely removed some information that clearly did not belong and succinctly explained why it didn't.
Regarding the title of this article perhaps it ought to be renamed "Industrial and three-phase power plugs and sockets". Are there any connectors in existence meant for polyphase power with more than three phases? I don't know of any.
CplDHicks (talk) 20:29, 25 July 2016 (UTC)
The problem here is the mistaken belief in the North American convention that the two lines which result from centre tapping a single phase transformer secondary (with the centre tap connected to ground) can still be regarded as a single phase! As the two lines are 180 degrees apart in phase, they are most definitely different phases. The fact that the convention is so widely accepted is simply an indication that you can fool most of the people for most of the time, but it remains, as I have already said, completely illogical. Americans seem to be completely hung-up on how the two lines are derived, and ignore the actual result. When discussing connectors, the source of the conductors is irrelevant to the function of the connector, all that matters is the voltage available, the current rating, and how many different poles there are. The two line poles on the connectors in question have different phases, therefore the connectors are NOT single phase! FF-UK (talk) 09:59, 26 July 2016 (UTC)
It took me a while to get used to, but yes the convention is that for transformers 180 counts as the same phase, since it is just a reversal of the wires. On the other hand, for multiphase rectifiers they do count separately. You can use a six-phase rectifier on three-phase power. Early US AC power generation was two phase, with the phases 90 degrees apart, and each center tapped. Gah4 (talk) 20:09, 26 May 2018 (UTC)
So now your argument is those ignorant Americans at NEMA don't understand their own connector design and an entire continent's people have been duped into misunderstanding their own electricity system. Thank goodness you're here to set us straight.
You're the one who's completely hung up on how the two lines are derived and ignore the actual result. Go find a 415 V three-phase source and grab an oscilloscope. Connect your oscilloscope to any of the two lines. Are you going to get two sine waves on your scope? Spoiler alert: no.
CplDHicks (talk) 16:01, 26 July 2016 (UTC)
That is a completely irrelevant challenge. However, if you connect three oscilloscope channels to the three lines of the three-phase source, using earth as the reference, you will see three sine waves with 120 degrees between each one. If you now connect two oscilloscope channels to the two lines on one of the NEMA connectors under discussion (assuming it is live), using earth (or neutral) as the reference, you will see two sine waves with 180 degrees between each.
Once upon a time some mainland European countries operated a system of distribution which involved two lines each having half the voltage upon it, the centre tap of the transformer was earthed, but no neutral was provided at the socket which meant that the connector could properly be described as single phase. However, the NEMA connectors under discussion DO provide a neutral contact, therefore they cannot be described as "single phase". (The German Schuko is a hangover from that system, although the two poles are now used as Line and Neutral. The legacy is that the Schuko has no polarization because in its original application there was no difference between the two lines!)
CplDHicks, in an earlier post you made the claim that: "In order to put this argument to bed I went to the source. From ANSI/NEMA WD 6-2016, pp. 42-44, 49-53, and the chart on p. 143: type '10' and '14' devices are for 125/250 volts SINGLE-PHASE."
I have looked at those pages, they contain absolutely no reference to "single phase" - you made that up!
FF-UK (talk) 21:08, 26 July 2016 (UTC)


And herein lies the fundamental misunderstanding on your part: "If you now connect two oscilloscope channels to the two lines on one of the NEMA connectors under discussion (assuming it is live), using earth (or neutral) as the reference, you will see two sine waves with 180 degrees between each." That's not how devices plugged into NEMA 10 and 14 receptacles work. To get 240 V the connected load will use the two 'hot' lines as their respective references, not the neutral. The neutral doesn't even come into play. It works no different than if the transformer secondary wasn't centre-tapped at all but had the 'hot' line at one end of the winding and grounded neutral at the other: exactly how you get your 240 V (nominal 230 V...) single-phase in your home in the UK. NEMA 6 devices use two 120 V 'hot' lines and no neutral: are they "two-phase"? NEMA 10 and 14 devices make use of the two 'hots' in exactly the same manner (when whatever it is that's connected needs 240 V). The neutral in a NEMA 10 or 14 device is used only when the connected load needs 120 V.
This is perfectly emblematic of how you're "hung up on how the two lines are derived and ignore the actual result". You're questioning my reference to ANSI/NEMA WD 6 in the same way: do you see "two-phase" anywhere in that document? Do you see the words "single-phase" on the various NEMA 1 or 5 drawings? No, you don't, because anything that is meant for polyphase power is called out, and everything else is for single-phase loads.
You know what works exactly same way as a NEMA 14 connector? Orange-coloured IEC 60309-2 industrial connectors. You're a man who loves standards and apparently believe NEMA are a bunch of morons, so you go look up Table 104 in IEC 60309-2 and tell me what the rated operating voltage is for the orange "2P+N+E" connectors with earthing positions at 12 o'clock. I can tell you it says "125/250 single-phase"—verbatim—in my copy, but let's see what yours says.
CplDHicks (talk) 23:23, 26 July 2016 (UTC)
I will quote again from CplDHicks earlier in this thread: "The NEMA 10 and NEMA 14 plugs and receptacles are meant to be wired to use a combination of one of the 120 V hot-to-neutral halves and the 240 V hot-to-hot. The controls and other electronics (incl. the dryer's drum motor) of a clothes dryer or range will use one of the 120 V hot-to-neutral connections, while the heating elements will see the full hot-to-hot 240 V potential difference." That seems to me to be a reasonable description, but it is a description of an appliance using two phases, which is, of course, what is available from the NEMA 10 and NEMA 14. Now the same editor is claiming "To get 240 V the connected load will use the two 'hot' lines as their respective references, not the neutral. The neutral doesn't even come into play."! As the editor has already stated, the neutral is required for the "controls and other electronics". Quite clearly, in explaining how an appliance derives its power we have to adopt one reference and stick to it, we cannot move the reference around and attempt to explain one part of the appliance circuit using one reference, and another part using a second reference. The phrase "the connected load will use the two 'hot' lines as their respective references" is meaningless gobbledygook. There IS a Neutral present. The Neutral IS used by the appliance circuitry ("controls and other electronics"). By convention, when a Neutral is present and in use, it is regarded as the reference. The 240 V is obtained by summing the two phases, each of 120V but of opposite phase.
The attempt to brush off the false quote from the NEMA standard is pathetic, disingenuous, and completely dishonest! And this from an editor who is very free with his accusations that I have not acted in good faith!
I am glad that CplDHicks has recognized the similarities between the NEMA 10 & NEMA 14 connectors and the "orange "2P+N+E" connectors with earthing positions at 12 o'clock" specified in IEC 60309-2. This similarity reinforces the point which I have been making. I quote from clause 7.5 of that standard:
"For rewirable accessories, the contacts shall be indicated by the following symbols.
for accessories with four contacts (three phase + earth):
L1, L2, L3, ♥ or alternatively 1, 2, 3, ♥
except for Series II clock position 12 h (phase + centre tap + phase + earth) which is marked: L1, N, L2, ♥"
(As the earth symbol which actually appears in the text of the standard is not available on WP, I have used: ♥ in place of it.)
The use of the terms "phase + centre tap + phase + earth" clearly confirms that the authors of IEC 60309-2 regard the orange connector as having two phases, just like the NEMA 10 & NEMA 14 connectors.
FF-UK (talk) 10:08, 27 July 2016 (UTC)

I'm done here. The only meagre attempt you have made at "consensus" was suggesting that perhaps the article should be moved to "Industrial and three-phase power plugs and socket". There's nothing left to discuss, now that you're resorting to ad hominem attacks ("...pathetic, disingenuous, and completely dishonest!"). Perhaps you should step away from the keyboard for a while, FF-UK. Cool down. You might come to realize, with a little time away from Wikipedia, that my only interest here was in improving the article.

CplDHicks (talk) 15:27, 27 July 2016 (UTC)

I have not made an ad hominem attack, but you have lied by misquoting a reference which did not, in any way, support your claim! You simply ignore all proof that your arguments are incorrect, and now appear to have run out of further attempts at justifying your misguided edit. You continue to ignore the facts because they do not suit your mistaken beliefs. You have not attracted any support for your changes, and as you have not, in any way, justified your reasons for deleting information from the article, then there is no reason for me not to replace it where it belongs (whilst maintaining some of your other edits to the article). FF-UK (talk) 16:30, 27 July 2016 (UTC)
The central problem here is that you just cannot and will not accept that centre-tapped, three-wire residential service to homes in North America is "single-phase". You said it earlier: "The problem here is the mistaken belief in the North American convention that the two lines which result from centre tapping a single phase transformer secondary (with the centre tap connected to ground) can still be regarded as a single phase! The fact that the convention is so widely accepted is simply an indication that you can fool most of the people for most of the time, but it remains, as I have already said, completely illogical." The real problem here is your assertion that "the North American convention" is "mistaken".
From Garland Group, a manufacturer of domestic kitchen ranges and commercial kitchen equipment, "NEMA Plug Guide": "[NEMA] 14 indicates 125/250 VAC, single phase, four wire, three pole"
From Schneider Electric, "The Different Types of AC Power Connectors in North America": Table 1, "AC power distribution system: Single-phase center tapped without safety ground ; Number of pins: 3; Application: Residential ovens and clothes dryers — AC power distribution system: Single-phase center tapped with safety ground; Number of pins: 4; Application: Residential large appliances"
From the Canadian Electrical Code Handbook: [1]
From The Lineman and Cableman's Handbook (published by McGraw-Hill, ISBN 0071467890): [2]
Over and over and over and over again: single-phase, single-phase, single-phase, single-phase... I've tried explaining why it's single-phase: you refuse to listen, you don't care. I've tried showing you proof: you dismiss it, ignore it, or smear me as a "pathetic, disingenuous" liar because you refuse to read it in context. I've tried warning you that you're safeguarding this article and other similar articles with the zeal of someone exhibiting "ownership": you don't care. I've suggested you step away from the situation, gather some perspective, and realize that I'm not out to lie and cheat my way into ruining this article I'm just here to improve it: you obviously don't believe me and just don't care.
For the very, very last time: consider the sources I have provided in this reply. Consider one of the largest domestic and commercial kitchen appliance manufacturers in the world, publishing a guide for installers, says NEMA 14 plugs are "125/250 VAC single-phase". Consider one of the largest electrical device manufacturers in the world published a white paper specifically about North American AC power connectors, and say "Single-phase center tapped without safety ground" (NEMA 10) and "with ground" (NEMA 14) connectors for residential appliances really are single-phase. Consider the Canadian Electrical Code says it's "single-phase, 3-wire". Consider a lineman's handbook, showing precisely how a centre-tapped transformer for North American residential use is "single-phase, 3-wire". Consider that half a billion North Americans know how their electrical power works, that they know how their domestic appliances work, that they know how their dryer and oven plugs work, and that they have not been systematically duped into believing an elaborate lie.
I am reinstating my edits to this page. Please heed my advice. Think long and hard about reverting again.
CplDHicks (talk) 20:53, 27 July 2016 (UTC)
I understand that the service is DERIVED from a single phase, but then it is SPLIT. You cannot split anything without creating multiple parts, in this case two. It is an illogical denial of the meaning of our language to say otherwise. Two definitions of "split" from Merriam-Webster: "to divide into parts or portions" and "to separate (the parts of a whole) by interposing something". Taking the latter definition, it is perfectly clear that what is "interposed" is the neutral connection which is then tied to ground. As I keep telling you, this results in two phases, 180 degrees apart. This is easily proved by observing the waveform at each phase relative to neutral, using an oscilloscope. There can be no disputing this, we have a lexical proof supported by a measurement proof. Examples of the misuse of the term "split phase" do nothing to support your mistaken ideas, they simply demonstrate that it is a common error. As long as a connector is used for neutral and two separate (different) phases, that connector is a multiphase connector. Wikipedia is not here to reinforce error, but to tell the truth. I note that no other editor has stepped in to support your case. Please stop edit warring. FF-UK (talk) 21:25, 27 July 2016 (UTC)

NEMA is basically a trade organisation which is notorious for ignoring International standards. It is not even a fully fledged standards body in the sense that, unlike electrical standards bodies in other countries, when it comes to connectors it concerns itself with physical dimensions and not with electrical specifications! NEMA is also notorious for complaining that it has insufficient influence on the International Electrotechnical Commission, not surprising when you consider how it ignores basic IEC standards. One of the problems with NEMA is that instead of using International English terms, as defined by the IEC, it continues to use Americanisms. 'Hot' to describe a conductor is an example of this, it has no recognition outside of North America, the international terms are 'phase' and 'line' (they basically mean the same thing in terms of conductors, with line being the more modern term). We do agree with the rest of the world on 'neutral' (which is, at some point, connected to ground, and is accepted as the reference point for measurements wherever you are). Most of the world uses 'earth' (or its local language equivalent, eg 'terre' in French, 'tierra' in Spanish) but our term 'ground' is close enough to not cause too many problems for non-American English speakers ('ground' is actually recognized by the IEC!)

We have to remember that people from all over the world use English Wikipedia, it is not just for Americans, and not even just for English speakers! It is no good having WP articles which are unintelligible to non-Americans. That does not just include the terminology, but the concepts as well. You cannot justify to a non-American that a connector which has two 'phase', or 'line' contacts is NOT a "multiphase connector", that is an example of our national arrogance.

I know that we have this somewhat crazy acceptance of 'split-phase' as still being 'single phase', but as FF-UK has pointed out, that is totally illogical, and technically wrong. I can see no justification for CplDHicks' insistence on removing connectors which have more than one phase contact from this article. As both CplDHicks and FF-UK have agreed, the IEC functional equivalent of these connectors is the orange IEC 60309-2 connector, and as FF-UK has shown, that is clearly identified as having two phases. Can we please end this rather silly spat and keep the NEMA 10 and NEMA 14 connectors here where they belong? 2601:703:1:2990:E9CD:43A1:E96F:7774 (talk) 03:45, 28 July 2016 (UTC)

As CplDHicks has now raised an edit warring complaint against me, I feel it appropriate to record a few more facts here. In particular, I am intrigued by the repeated allegations of "ownership" made against me! The NEMA 14 information was first added on 25th September 2004. The NEMA 10 information was first added on 2nd February 2005. By 13th June 2006, both subsections were in the form which CplDHicks (who shows no evidence of any previous interest in WP connector articles) arbitrarily deleted on 23rd June 2016. During the intervening 10 years no one appears to have queried the presence of these connectors here, and there is no record in the talk history of any discussion about those types having been raised. My own WP editing career started in August 2012, my only prior editing of this article was on 30th September 2015 when I added information about Swiss three-phase connectors. Ownership?!?!
CplDHicks has drawn attention to the similarity of the "orange "2P+N+E" connectors with earthing positions at 12 o'clock" specified in IEC 60309-2, and I have quoted from that standard as to how the poles are to be indicated in connectors: "(phase + centre tap + phase + earth) which is marked: L1, N, L2, ♥". NEMA markings do not follow the IEC conventions, on two-pole and earth connectors the 'hot' may be indicated by the word "hot" or may be left unmarked, the neutral is indicated by the word "white" for the colour of the wire which should be connected to it. In the ANSI/NEMA WD 6-2016 standard the configuration diagrams for 2 pole 3 wire grounding connectors use the designation 'G' for ground, the designation 'W' for neutral. and the 'hot' pin is left unmarked. However, in configuration diagrams for three-phase connectors, the three phase pins are designated 'X', 'Y' and 'Z', with the designation 'G' for ground, and designation 'W' for neutral. In NEMA 10 connectors, the two phase pins are designated 'X' & 'Y', with the designation 'W' for neutral. In NEMA 14 connectors the two phase pins are designated 'X' & 'Y', with the designation 'G' for ground, and designation 'W' for neutral. The use of the two phase designators 'X' & 'Y' is another clear indication that these are TWO PHASE CONNECTORS!
I am left with the clear impression that CplDHicks has driven by this article, found it not to his personal liking, and decided that it is OK to remove two significant sub-sections. When challenged, he has demonstrated a lack of understanding of the issues, and has resorted to falsifying a reference in a vain attempt to defend his PoV. He has raised lots of defences, but each time his defences are shown to be flawed he offers no acknowledgement of the error, engages in no meaningful discussion, but simply comes up with an alternative defence. He has shown no interest in achieving a consensus, but demonstrated a belief that his PoV should prevail, no matter what the facts are. FF-UK (talk) 10:46, 28 July 2016 (UTC)
I have often found that a very useful reference document, written in international terminology, is "International electrical standards and regulations" published by Legrand and downloadable from them at: http://www.legrand.com/files/fck/File/pdf/Guide-International.pdf The following quotes are taken from the American section of that document. On page 50: "SUPPLY- Domestic supply is usually 2 phases (120 V/240 V - 60 Hz). 2 phases + neutral are supplied. Neutral is re-earthed at entry. Earth is local." Also on page 50: "POWER CIRCUITS - Appliances having heavy power consumption (ranges, water-heaters, etc.) are supplied on a specific circuit, often 120/240 V. Various socket outlets of appropriate ratings are available, these are non-interchangeable, thus 2 Phase + Neutral + Earth plug cannot be fitted to a 2 Phase + Earth socket, etc." These references make it obvious that, in international terms, our 120 V/240 V connectors are regarded as two phase. 2601:703:1:2990:E9CD:43A1:E96F:7774 (talk) 21:19, 28 July 2016 (UTC)
Thank you, IP editor, for that very useful contribution. It is obvious that a lot of the confusion illustrated in the above exchange is based on a lack of understanding of the terms used outside North America. In an effort to clarify this I have added to this article an adapted and expanded version of the "Concepts and Terminology" section from AC power plugs and sockets. FF-UK (talk) 15:26, 30 July 2016 (UTC)
Maybe this is settled now, but anyway ... 120/240 center tapped is considered one phase. I might disagree, but that is the WP:COMMONNAME. (Unless it is input to a rectifier, in which case it is two.) But I don't think you can call two phases and neutral of 120/208 single phase. They are not 180 degrees apart. For a load using only phase to phase, then there is only one phase. US water heaters, even heat-pumps with electronics and fans, run off 240 or 208 single phase, no neutral and no fake neutral using ground. Gah4 (talk) 20:29, 2 December 2020 (UTC)
As for the other question, I suspect that NEMA 10 and 14 are often enough used in industrial environments to be described here. That is independent of the number of phases you want to assign to them. Maybe not as much as twist-lock, but often enough. Gah4 (talk) 20:29, 2 December 2020 (UTC)

Sockets for loading electric cars[edit]

These sockets are also multi-phase and often provide loading through three-phase currents (if not DC). Either include here of provode a link to a resepctive page. Meerwind7 (talk) 08:45, 8 January 2018 (UTC)

NEMA 10 and 14, again[edit]

Regarding the removal of a section on NEMA 10 and 14. While these are commonly used in residential environments (US, at least), I suspect that they are sometimes used in industrial, or similar environments. NEMA 10 used to be usual for electric dryers and ranges, either on 120/240 (home) or 120/208 (non-home residential, such as dormitories and apartments). NEMA 14 is now supposed to be used in those cases for home use, I don't know about industrial use. What connector is used for laundromats? I believe that they are sometimes used for higher power copying machines, too. As noted, in many cases they are used with two phases of a 120/208 supply. For NEMA 10, there is always the question about the third pin being neutral or ground. With NEMA 14, there is a separate neutral pin. In either case, when connected to a 120/208 circuit it seems to me that they are multiphase. It might be that a section with a header, and a short description with a link to the NEMA page would be fine. Gah4 (talk) 20:22, 26 May 2018 (UTC)

Here is an industrial grade NEMA 10-50 connector]. It doesn't look like one would use for home powering an electric range. Gah4 (talk) 20:42, 26 May 2018 (UTC)

You "suspect" they are "sometimes" used in industrial environments. My dear Gah, I have two words: citation needed.
We already direct the reader to NEMA connector for more info, where the sections on 10 and 14 plugs and receptacles are repeated (almost) verbatim. The most common uses for 10 and 14-series connectors—by far—are domestic clothes dryers and ranges; definitely not industrial. As such they don't merit any particular mention in this article. (Whereas twist-lock connectors, no matter the particular voltage or phase, are much more common in industrial settings therefore they do merit the particular mention they get here.) I would wager the single most common 'industrial' NEMA connector is in fact the simple NEMA 5 three-prong, the same as used in the home but beefed up for robustness and durability's sake. We already state as much: "NEMA devices are not exclusively industrial devices, and some types are found in nearly all buildings in the United States. "Industrial-grade" connectors are constructed to meet or exceed the requirements of more stringent industry testing standards, and are more heavily built to withstand damage than residential and light commercial connectors of the same type."
As for being "multiphase", if you plug a device into a NEMA 10 or 14 receptacle you're only going to get single-phase power out of it. It doesn't matter whether it's wired to a panel fed from 120/240 split-phase or two of the line conductors from a 120Y208 transformer: you're going to get 240 V or 208 V single-phase—one sine wave—from one line conductor to the other. The appliance doesn't 'know' any different.
Making subheadings for single-phase, residential dryer and range plugs in this article is, was and always will be patently absurd. As such I removed them, and they will stay removed. CplDHicks2 (talk) 03:20, 27 May 2018 (UTC)
So, Grainger makes industrial plugs and receptacles that no-one uses in industry? Sounds like a good way to go out of business. Note that they specifically state that they are industrial, and are industry yellow instead of residential gray. How many have to get used in industry to count? Gah4 (talk) 08:50, 27 May 2018 (UTC)

wye and delta[edit]

Should the article discuss wye and delta, and which connectors are used with which? Gah4 (talk) 01:43, 3 December 2020 (UTC)

No. This isn't a textbook. --Wtshymanski (talk) 01:45, 3 December 2020 (UTC)
No, I didn't mean textbook, but how otherwise do you explain the difference in connectors? People do need to know that there are two kinds of connectors, and so should somehow be explained. Gah4 (talk) 04:20, 3 December 2020 (UTC)
Large potable electrical welding machines in Europe are often 380 to 440 volts single phase and are connected between two phases via a plug that has no need of a neutral connection. But in any event, a three phase load does not have to be balanced just as long as there would be no neutral current (including triplen currents) to require a neutral pin. 86.142.79.215 (talk) 13:42, 3 December 2020 (UTC)