Talk:High-leg delta

Open delta high leg
I have seen multiple instances of High leg implemented with two transformers in open delta configuration, where the neutral is the center tap of one of the transformers. I am trying to describe this and do not understand the objection that has twice been made.

I just found a good diagram of this, as the last one on the page: http://www.bmillerengineering.com/elecsys.htm and also Figure 10-18 in this book http://books.google.com/books?id=8cT8D9_WP7MC&pg=PA251&lpg=PA251#v=onepage&q&f=false BillHart93 —Preceding undated comment added 20:41, 17 October 2010 (UTC).


 * The proposed edit said something like "one of the three transformers may be omitted" which is confusing to the reader since the object described in teh schematic diagram is called "a transformer". This three-phase transfomrer could be made out of a set of three individiual single-phase transformers, in which case an open delta would further allow only two transfomrers to be used. But was this in fact done?  The point of high-leg delta was to provide for a small 120 V load in an otherwise 3 phase 240 volt distribution network, which would have been primarily 3 phase loads, warranting a 3-transformer bank (or a three-phase transformer). The citation in the proposed reference warnsa bout high-leg connections and shows an open-delta connection, but doesn't show an open-delta high-leg.  --Wtshymanski (talk) 21:52, 17 October 2010 (UTC)

Diagrams in both links show open delta high leg with two transformers. As pointed out the first link needs to be scrolled to the bottom of its page. The second one points out Figure 10-18. Maybe you didn't look at all the figures?

The purpose of using high leg may sometimes be to provide for a small 3-phase load along with substantial single-phase loads, for which open delta works well. When the 3-phase load is large, all three are needed. I have seen more instances of open delta high-leg than with the full 3 transformers or 3-winding transformer.

Will you let me post my addition if I clarify that I am talking about the case of separate transformers and include specific warning about poor load capacity?

BillHart93 (talk) 01:10, 18 October 2010 (UTC)
 * You don't ask my permission or anyone else's to change an article here. But please make it clear and tie it to good references, not someone's hobby project or someone selling something. I see at the bottom of the cited web page an open delta/open delta connection, but I don't see a figure showing a center-tapped winding giving 120 v on either side of a neutral and a second winding giving a third phase in open delta. One figure is not rendering in either of the browsers i have installed on this machine. Speaking theoretically, why would anyone install an open delta on a system that is mostly 3-phase loads and then center-tap one winding for 120 v lighting?  I don't believe this was ever an intended application and I'd appreciate a better reference showing this was common or done at all for high-leg delta systems.  We're not talking about some sunday 3 AM improvisation an electrician dreamed up, we should be talking about the way systems were designed to be operated. ---Wtshymanski (talk) 01:30, 18 October 2010 (UTC)
 * Hmm. Google Books is being mean about showing the pages that talk about both "open delta" and "high leg delta" on the same page. This may mean going to a real library. The Federal Pacific Web site would be more credible if it could spell "neutral" correctly. --Wtshymanski (talk) 01:43, 18 October 2010 (UTC)

Another link with pictures showing both ways: http://www.markrobisonpe.com/electrical/delta-high-leg-diagram/ —Preceding unsigned comment added by BillHart93 (talk • contribs) 02:14, 18 October 2010 (UTC)

Shape of sinewave from high leg to neutral?
Since the high leg to neutral is not exactly equal to one phase or one-half phase, it seems like it may have an unusual sinewave in addition to its unusual voltage. What does the sinewave graph look like for the high leg as the voltage rotates across the three phases? DMahalko (talk) 11:48, 19 August 2009 (UTC)

I've added a figure showing the voltages.--gargoyle888 (talk) 03:47, 20 August 2009 (UTC)

Single phase loads on high load
I'm going to edit out the part about single phase fluorescent lights on the high leg. Doing that is a violation of the NEC.  a remark by User:Wefoij,  17:34, 13 April 2010  
 * I'm not that familiar with the NEC NFPA 70 and a quick look through my 2005 edition doesn't show which rule prohibits this. If you change it, can you please cite the NEC rule? --Wtshymanski (talk) 13:34, 14 April 2010 (UTC)
 * After some reading, it may not be prohibited so much as just useless. Connecting to the high leg lets you use 208 V single-phase devices, but you've already got a perfectly good 240 V single-phase voltage; you wouldn't want to have two different voltages of lamp ballasts in the same facility. You don't gain much in transformer loading because all the high-leg current must also pass through the center-tapped leg of the supply transformer. Does the NEC prohibit single-pole breakers on the "orange" phase, if so, you would have to use a 3-pole breaker and waste 2 poles to use the high-leg. Probably better to take it out. --Wtshymanski (talk) 15:10, 14 April 2010 (UTC)

"As idiosyncratic as ring circuits; restore" per Wtshymanski
Please explain the snarky edit remark you made in this diff. NEC this, NEC that. NEC is absurdly useless outside of United States and my edit was meant to retain relevance to the concept of center tapped high-leg delta without rhetoric to arbitrary American codes that are of no technical relevance.

240v over 208V is not an "advantage". It just happens to coincide with equipment voltage that was arbitrarily chosen historically. Does 960V have advantage over 832V? Cantaloupe2 (talk) 22:08, 21 December 2012 (UTC)

If you have examples and regulatory codes from other countries that appear relevant, please add them, and note country-specific information, but do not remove information just because it does not apply world-wide. BillHart93 (talk) 00:57, 22 December 2012 (UTC)


 * It also is not really relevant to the topic in technical point of view, because it only talks about regulatory issues for one country. I think that we need to focus more on classroom like materials. Field experiences and such that focus heavily around application to local standards are often completely useless outside of that traditions. Current practices aren't necessarily based on technical reasons, but for historical reasons and those merit detailed discussion here much like 120v vs 230v at home, 50 Hz vs 60Hz discussion. Cantaloupe2 (talk) 00:59, 22 December 2012 (UTC)
 * Greetings, I am responding to a request made at WP:3O. I agree that it is important that the article include a global scope, but this does not mean that NEC recommendations have no place in the article. The solution is to add usage and requirements that apply to the rest of the world, not stub the article simply because much of the contributions so far have been "60Hz-centric". Actual technical practice, whether due to the underlying physics or simply because of tradition, absolutely does have a place in the article. Please try to remember WP:BRD and WP:CIVIL, and come to the talk page to discuss rather than un-doing a revert. VQuakr (talk) 20:56, 22 December 2012 (UTC)

Confusing first hand reflective writing
" The other method requires two interconnected transformers. One transformer is connected to one phase of the overhead primary distribution circuit to provide the 'lighting' side of the circuit (this will be the larger of the two transformers), and a second transformer is connected to another phase on the circuit and its secondary is connected to one side of the 'lighting' transformer secondary, and the other side of this transformer is brought out as the 'high leg'."

This is not referenced at all and I have no idea what the editor is talking about. It looks like its a an experience based reflection someone wrote. I pulled it aside for adding sources and so it can be rephrased in a way that makes sense. Cantaloupe2 (talk) 22:09, 23 December 2012 (UTC)


 * I understand exactly what he is describing and that was the way it was done in our area. (wye to open delta trnsformation) It was usually created by a customer with a single / split phase transformer running his store lighting wanting to add a small three phase motor (butcher shop meat cutter comes to mind) and the utility would add another transformer on the pole and one more conductor into his building. Cheap and dirty solution. These have mostly been replaced with 3-ph 4w wye systems now. The standard replacement system takes one more transformer can but it makes the installation standard, very common and the metering less exotic. Where are you seeing this statement? I couldn't find it. 174.118.142.187 (talk) 04:36, 24 December 2012 (UTC)


 * I pulled it aside until references can be added. You said you've never seen the phrasing "high leg delta". So were these systems not grounded at the center tap of one of the transformers?  In any case, the encyclopedia needs to be written in a way and referenced such that its understandable to someone other than electrical wiring technicians. As far as commonality, wrong assumptions get made. "very common" standard, etc should stay out of actual article. If you ask someone in Canada in a region where bags of milk are commonly sold, they'll say "its very common" where if you ask someone in USA you'll hear "exotic, uncommon, rare".  Do you mind registering an account?  There are many IP editors and its an unreasonable expectation for others to keep track of who is who.  You can tell who I am, because of name recognition.  For you, you just get muddled in with rest of IP editors.   Cantaloupe2 (talk) 05:06, 24 December 2012 (UTC)
 * Yes these systems were grounded at the cente-tap of the winding. We just called them 3 phase 4-wire delta as they are defined by government metering standards people in Canada by the shape of the system phasors. I agree that terms are a problem and some are relative. Even if I called this system unusual it is still a relative term to common in this area. I guess any term describing a difference is relative. Exotic seems to be a problem for you so I will try to avoid it. 174.118.142.187 (talk) 13:15, 24 December 2012 (UTC)


 * WP:PEACOCK is a good start. I would prefer eliminating adverbs that we can do without where inclusion is not absolutely justified and the statement is supported by reference and in global sense. This article maybe better off renamed to Three phase delta (electrical wiring) and variants added under it. Cantaloupe2 (talk) 21:32, 24 December 2012 (UTC)

While the description is clear to me, with years of anakysis experience in these connections, I agree the description is too abstract for most readers. I think it should be included but it needs to be simpified somewhat. Maybe eliminate the primary connection details and just say something about a second phase. That's all it takes to get a second 60 degree potential. 174.118.142.187 (talk) 05:27, 29 December 2012 (UTC) --- I was warned (edit war) about a reversion I made so am staying out of it for a while so I don't lose my privileges, but I feel Cantaloupe2 is going too far in restricting the content of the article. As noted above by me and another reviewer, the cure for regionalism is to add information about the rest of the world, not to delete good information about the region that is represented. BillHart93 (talk) 16:24, 3 January 2013 (UTC)
 * What I did was purge a bunch of anecdotal non-sense such as presenting "240v" as an "advantage" over 208v and substantially rewrote in a regionally blind manner. This means absolutely nothing and does not represent a system advantage by simply stating that it is more compatible with regional equipment. Now a whole bunch of unreferenced, anecdotal reflection had been put back on. I still feel that American "NEC" this, American "NEC" that is straying off topic for worldwide interestCantaloupe2 (talk) 16:30, 3 January 2013 (UTC)
 * The edits you have done to this article (and a few others) amount to not much more than a personal vendetta against American anything. This appears to another attempt to eliminate anything that mentions a North American numeric example. You have been advised on several occasions and here again, including your WP:3O request response, not to keep removing "America-centric" data from the articles, but rather, to add your own data for other geographic areas. Each time your POV edits are discussed and you are advised to desist you then appear turn to disrupting articles by injecting large quantiies of I doubt it tags making the article appear complete junk to readers.  This WP:Pointy behaviour discourages other editors from particpating and is WP:Disruptive to the WP environment. Attempts to discuss issues with you on talk pages have resulted in non-response after your typical initial confusion technique using a technically confused side-track attempt with what appears to more technically adept editors to be nonsense. Mostly editors just  ignore your comments and just revert your efforts.  In other edits  you make multiple section edits (appears as stealth edits) in one edit with an edit history commenting on one small, unimportant edit, that frustrates other editors, causing them to revert your whole edit. I tried to explain this to you on your talk page previously but no collaboration has been noticed on that front. Your constant challenging most edits in these subjects, combined with your seeming lack of WP:Competence and these other problematic habits, makes this behavior WP:Disruptive. Let's not force this issue any further than here as it wastes all of our time. 174.118.142.187 (talk) 21:50, 5 January 2013 (UTC)

Wth's section revisited
So, I invited him to comment on Dec 21 2012 when his reversion was contested. He never addressed it. I have already explained that the ability to use 240v over 208v is not an advantage that can be attributed to high-leg delta, because a specific voltage value is of no inherent value. That's an America only "technical" practice arising out of products made for 240v out of historical reason. A bunch of the removed contents pertain specifically to America only technical practices.

per our third party comment, "Actual technical practice, whether due to the underlying physics or simply because of tradition, absolutely does have a place in the article".

WP:V is an expectation and burden is on the inserting side after the contents are challenged. The reversion re-inserts a whole lot of original research and opinion statements like what I've described above.

Cantaloupe2 (talk) 21:17, 3 January 2013 (UTC)

POV statements
It has been stated somewhere by Spinning that Wikipedia articles should address the topic globally.

The prose " The advantage for 480Y/277 volt three-phase system is is that 277 single-phase wiring methods and materials are "300 volt class" " This is POV non-sense. "300v" class is an arbitrary classification invented by America regulations called the "NEC" and it is not a representation of technical advantage. It is an American regulation politics advantage specific to the countries of United States and Canada. What usefulness does something like this have on global scale and from technical view? If the writings of the America code regulation called the "NEC" was rewritten to classify 250 and above to go into the "600v" class, this proclaimed advantage disappears even if there was no actual change to the system. Cantaloupe2 (talk) 21:27, 5 January 2013 (UTC)

Transformer Drawing -- L3 vs. L2 vs. L1
Hi All,

The first drawing shows the high-leg to be L3 on the transformer. The high-leg is normally the B-Phase; an odd explanation is given as to why L3 is winding up (pun) as the B Phase on the panel:

"By convention, the high leg is usually set in the center (B phase) lug in the involved panel, regardless of the L1-L2-L3 designation at the transformer."

Note the drawing of a real transformer that follows shows the high-leg as "Secondary B", which would make it L2, which would be correct. And L2 would make the high-leg Phase B which is usually orange in 3-phase 480V systems.

The first schematic drawing needs to be modified to match both the real drawing and the real world. Drmemory (talk) 15:19, 16 August 2016 (UTC)

Hi,

Just to complicate things in Canada the high leg is Phase A (L1) instead of Phase B as per the CEC rule 4-038 (4): "Where the midpoint of one phase of a 4-wire delta-connected secondary is grounded to supply lighting and similar loads, the conductors shall be colour-coded in accordance with Subrule (3) and the phase A conductor shall be the conductor having the higher voltage-to-ground".

The reference to subrule (3) means that the high phase is red instead of orange in Canada too.

Maybe some reference to this could be added? I am not confident to edit Wikipedia at work though.

207.34.120.71 (talk) 17:36, 3 October 2016 (UTC)

While we're fixing things, n should be shown at the origin of the phasor diagram. R2G2 (talk) 19:58, 1 November 2016 (UTC)

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What countries
In what countries is this system used? Only in the US? --Apoc2400 (talk) 09:55, 4 April 2017 (UTC)

In Saskatchewan, Canada for existing installations. See Page 5. http://www.saskpower.com/wp-content/uploads/electric_service_requirements_section1.pdf 142.165.85.74 (talk) 18:04, 20 April 2017 (UTC) -- These are anecdotal, not good references:

http://www.electriciantalk.com/f2/high-leg-delta-circuit-22901/

It states that "In Germany (where I'm from), the high-leg delta circuit is very unusual."

Also: https://news.ycombinator.com/item?id=13795700

"In most parts of Europe 3-phase is the standard. Neither high-leg delta nor split phase have significant deployment outside North America."

These lead me to expect that it is rare but not unknown in Europe. BillHart93 (talk) 14:23, 21 April 2017 (UTC)
 * BTW, split phase 230/460 used to be common in Europe and is still common in Australia with its SWER lines. - Yuhong (talk) 05:47, 2 December 2018 (UTC)
 * Split phase is not three phase. This article is about a combination of a three-phase distribution system with a split-phase distribution system. --Wtshymanski (talk) 19:23, 3 December 2018 (UTC)