Closed Delta 120/240V 3-phase service



Currently, the area around Vancouver BC. Other residential areas with single-phase service: near Waterloo, Toronto, and St. Catharines Ontario, near Montreal Quebec.
Where do you live that has full three-phase MV on top of every pole on every street in a residential area? And three transformers on every pole that has a transformer?

Not where I live now, nor where I've lived for decades. Again, where do you live that has 3-phase on the pole outside every house?
    Dave
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The transformers aren't on every pole (every third), but the wires are. I see it all over. All you have to do is look.

Everywhere I've lived (some underground).
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|> |> >> In all of the places I've lived, residential areas had |> >> single-phase service only: a single MV line running down the top of the |> >> poles along the street or alley, and single-phase transformers |> >> providing center-tapped 120/240 service to several houses per |> >> transformer. |> |> >Where do you live, Mongolia? The only places I've seen single phase |> >distribution is in the middle of the country (rural Vermont, in |> >fact). |> |> Currently, the area around Vancouver BC. Other residential areas with |> single-phase service: near Waterloo, Toronto, and St. Catharines |> Ontario, near Montreal Quebec. |> |> Where do you live that has full three-phase MV on top of every pole on |> every street in a residential area? And three transformers on every |> pole that has a transformer? | | The transformers aren't on every pole (every third), but the wires | are. I see it all over. All you have to do is look.
There are lots of distribution lines with all three phases. There are also lots with just one phase. Either way, just one transformer is the norm for residential services.
|> >> Given the amount of area covered by single-family houses |> >> compared to the area used by commercial/industrial/large residential |> >> (high rise), I'd have to guess that more than 50% of the total number |> >> of poles that have any transformers carry one single-phase |> >> transformer. |> |> >Your *guess* is wrong. |> |> Not where I live now, nor where I've lived for decades. Again, where do |> you live that has 3-phase on the pole outside every house? | | Everywhere I've lived (some underground).
You manage to only live in strange places.
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snipped-for-privacy@ipal.net says...

Good grief, Phil! Read! It's not distribution, rather service! The three secondary phases *ARE* on the poles.

Nope, Midwest, Northeast/New England, but I see it everywhere.

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| snipped-for-privacy@ipal.net says...
|> |> |> |> >> In all of the places I've lived, residential areas had |> |> >> single-phase service only: a single MV line running down the top of the |> |> >> poles along the street or alley, and single-phase transformers |> |> >> providing center-tapped 120/240 service to several houses per |> |> >> transformer. |> |> |> |> >Where do you live, Mongolia? The only places I've seen single phase |> |> >distribution is in the middle of the country (rural Vermont, in |> |> >fact). |> |> |> |> Currently, the area around Vancouver BC. Other residential areas with |> |> single-phase service: near Waterloo, Toronto, and St. Catharines |> |> Ontario, near Montreal Quebec. |> |> |> |> Where do you live that has full three-phase MV on top of every pole on |> |> every street in a residential area? And three transformers on every |> |> pole that has a transformer? |> | |> | The transformers aren't on every pole (every third), but the wires |> | are. I see it all over. All you have to do is look. |> |> There are lots of distribution lines with all three phases. There are |> also lots with just one phase. Either way, just one transformer is the |> norm for residential services. | | Good grief, Phil! Read! It's not distribution, rather service! | The three secondary phases *ARE* on the poles. | |> |> >> Given the amount of area covered by single-family houses |> |> >> compared to the area used by commercial/industrial/large residential |> |> >> (high rise), I'd have to guess that more than 50% of the total number |> |> >> of poles that have any transformers carry one single-phase |> |> >> transformer. |> |> |> |> >Your *guess* is wrong. |> |> |> |> Not where I live now, nor where I've lived for decades. Again, where do |> |> you live that has 3-phase on the pole outside every house? |> | |> | Everywhere I've lived (some underground). |> |> You manage to only live in strange places. | | Nope, Midwest, Northeast/New England, but I see it everywhere.
I've lived in some of these areas plus the south. I've never seen any kind of three phase service besides wye (either 208Y/120 or 480Y/277 and in one case 600Y/347) and delta (presumably 240D/120 since there was a center tapped leg on the few I've seen) for three phase and split phase (240/120) for single phase. I've also seen some 2-wire single phase feeding some highway lighting, but I did not know the voltage (could be any of 120, 240, 277, 347, 480, 600 as far as I know).
You're sure none of these are in any abundance where you live?
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says...

In a residential neighborhood? Get real!
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|> I've lived in some of these areas plus the south. I've never seen any kind |> of three phase service besides wye (either 208Y/120 or 480Y/277 and in one |> case 600Y/347) and delta (presumably 240D/120 since there was a center |> tapped leg on the few I've seen) for three phase and split phase (240/120) |> for single phase. I've also seen some 2-wire single phase feeding some |> highway lighting, but I did not know the voltage (could be any of 120, 240, |> 277, 347, 480, 600 as far as I know). |> |> You're sure none of these are in any abundance where you live? | | In a residential neighborhood? Get real!
So do you want to detail which of these systems are available to which classes of customer (residential vs. commercial) in the areas where you see them, and approximately what percentage of all service drops use which?
1. single phase 2-wire 120 volt only 2. single phase 3-wire 120/240 volt edison split phase 3. single phase 3-wire 120/208 volt (2 poles of 208Y/120) 4. single phase 2-wire 240 volt only 5. single phase 3-wire 240/480 volt edison split phase 6. single phase 3-wire 277/480 volt (2 poles of 480Y/277) 7. single phase 2-wire 277 volt only 8. single phase 2-wire 347 volt only 9. single phase 2-wire 480 volt only 10. single phase 3-wire 347/600 volt (2 poles of 600Y/347) 11. single phase 2-wire 600 volt only 12. three phase 4-wire 240 volts closed delta, center tapped at 120 volts 13. three phase 4-wire 240 volts open delta, center tapped at 120 volts 14. three phase 3-wire 240 volts closed delta 15. three phase 3-wire 240 volts open delta 16. three phase 3-wire 480 volts closed delta 17. three phase 3-wire 480 volts open delta 18. three phase 3-wire 600 volts closed delta 19. three phase 3-wire 600 volts open delta 20. three phase 4-wire 208/120 volt wye 21. three phase 4-wire 240/139 volt wye 22. three phase 4-wire 416/240 volt wye 23. three phase 4-wire 480/277 volt wye 24. three phase 4-wire 600/347 volt wye 25. three phase 4-wire 1000/577 volt wye 26. three phase 4-wire 120/240 volt Scott-T with 208 volt high leg. 27. six "phase" 7-wire 240/208/120 volt "6 star"
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replying to phil-news-nospam, Gary wrote:

The HV lines aren't the concern here. Many "country" single primary HV is common with many xformers off 7620V to supply homes with 240/120V. Although sometimes there may be "banks" of xformers on one pole. This does not constitute 3 phase, just a number of homes off the pole. Three phase 13200V HV also runs through some residential areas with the secondary xformer fed off one 7620 phase. Each xformer has one "bug" as a primary feed. But if, per chance, a large business requires 3 phase, it's there. Basically depends on a number of factors. Who installed the primary, is it municipal, is it conglomerate, and what was their budget? And remember, one xformer may feed a number of homes in some areas.
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On Wed, 17 Jun 2015 02:18:01 +0000, Gary

In SW Florida the typical medium voltage distribution is single phase on each run through the neighborhoods. They split out the 3p primary at the main streets. It is 13.5kv to ground.
http://gfretwell.com/electrical/Feed%20on%20Pinetree%20Lane.jpg
This is the typical transformer feeding 2-3 houses on the 120/240v bus at the bottom.
http://gfretwell.com/electrical/transformer%20feeding%20a%20120-240%20bus.jpg
When I have seen center tapped delta, it is usually only done with 2 transformers (delta vee)
http://gfretwell.com/electrical/red%20leg%20transformers.jpg
I did see 120/240 delta with 3 transformers in the keys but it probably grew into 3. (note the center tapped transformer is bigger than the other 2.)
http://gfretwell.com/electrical/Transformers_at_hogs%20_breath.jpg
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On 06/16/2015 10:18 PM, Gary wrote:

Hello, and as they say, "everything is relative". What you labeled as "HV" in your reply is generally considered to be medium voltage (MV) in electric power distribution terminology. The three (sometimes less than 3) wires seen on the cross arms of utility poles (usually up to 34 kV line-to-line) are MV, not HV. The voltage levels for the MV designation have changed over the years depending on what IEEE and or NEMA standard is being referenced but currently in the US the range is from just under 1 kV to 69 kV. It may be "MV" but it can kill you instantly. Sincerely,
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I *have* looked where I live. I've told you what I see (a single MV wire on the top of the vast majority of poles in residential areas). The next level up the distribution hierarchy is 3-phase, so 3-phase lines do pass through residential areas, but only one phase is tapped for the line of poles down each street or alley.
Again, where do you see 3-phase on every pole? Tell us some places. Even when there are 3 phases, do the transformers occur in groups of 3? Or do you mostly get one transformer per pole, tapping only one of the 3-phase MV lines? (That's what I see when there does happen to be 3-phase distribution).

And where would that be? City or suburbs?
    Dave
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Afghanistan?
Illinois, New York, Vermont (haven't looked here in OH).

Sure.
One pig per pole, three wires going between poles, under the MV lines.

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|> |> >> Currently, the area around Vancouver BC. Other residential areas with |> >> single-phase service: near Waterloo, Toronto, and St. Catharines |> >> Ontario, near Montreal Quebec. |> |> >> Where do you live that has full three-phase MV on top of every pole on |> >> every street in a residential area? And three transformers on every |> >> pole that has a transformer? |> |> >The transformers aren't on every pole (every third), but the wires |> >are. I see it all over. All you have to do is look. |> |> I *have* looked where I live. I've told you what I see (a single MV |> wire on the top of the vast majority of poles in residential areas). | | Afghanistan?
If I ever get there, I'll tell you what I see, if I make it back. But I have read some descriptions that would suggest something like 380Y/220 for three phase.
|> The next level up the distribution hierarchy is 3-phase, so 3-phase |> lines do pass through residential areas, but only one phase is tapped |> for the line of poles down each street or alley. |> |> Again, where do you see 3-phase on every pole? | | Illinois, New York, Vermont (haven't looked here in OH).
Maybe you should. You'll find a LOT of 208Y/120, some 480Y/277 (larger buildings), and maybe some leftover 240D/120, as well as single phase service in 240/120. But do take your camera if you are convinced there are some "6 star" services around.
|> Tell us some places. |> Even when there are 3 phases, do the transformers occur in groups of 3? | | Sure.
And how many lugs on each are wired up? Does each transformer have the same number of MV bushings (whether that be 1 each or 2 each)?
|> Or do you mostly get one transformer per pole, tapping only one of the |> 3-phase MV lines? (That's what I see when there does happen to be |> 3-phase distribution). | | One pig per pole, three wires going between poles, under the MV | lines.
That's single phase 240/120 of the Edison split phase variety. No three phase services there.
Look for cases of THREE transformers, each with the same number of MV bushings (either all have 1 or all have 2 each), and at least 3 LV lugs connected on all three. If only 2 lugs are connected on all three, then you have a wye system, usually 208Y/120 but 480Y/277 is possible (600Y/347 is very rare except in Canada). If 2 lugs are connected on 2 transformers and 3 lugs are connected on one transformer, it is probably 240D/120.
Other possibilities also exist. Be sure to get a number of photos at many different angles to get an unambiguous view of exactly how all the wires are connected. If you see one with 3 lugs connected on each of 3 separate transformers, where the middle lugs of each are connected together, and all the outer lugs, plus the joined middle lugs as one wire, supply 7 wires into whatever building is served, then be sure to get a LOT of photos.
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says...

They surely wouldn't be called that because it's a stupid idea.

Never climbed a pole, but all three phases are used for Edison 240V service. How may lugs is that?

Bullshit! The three wires were the three phases. You could see the connections on the pigs.

Exactly!
I'm not in the business of supplying your curiosity.
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| says...
|> |> |> |> >> Currently, the area around Vancouver BC. Other residential areas with |> |> >> single-phase service: near Waterloo, Toronto, and St. Catharines |> |> >> Ontario, near Montreal Quebec. |> |> |> |> >> Where do you live that has full three-phase MV on top of every pole on |> |> >> every street in a residential area? And three transformers on every |> |> >> pole that has a transformer? |> |> |> |> >The transformers aren't on every pole (every third), but the wires |> |> >are. I see it all over. All you have to do is look. |> |> |> |> I *have* looked where I live. I've told you what I see (a single MV |> |> wire on the top of the vast majority of poles in residential areas). |> | |> | Afghanistan? |> |> If I ever get there, I'll tell you what I see, if I make it back. But |> I have read some descriptions that would suggest something like 380Y/220 |> for three phase. |> |> |> |> The next level up the distribution hierarchy is 3-phase, so 3-phase |> |> lines do pass through residential areas, but only one phase is tapped |> |> for the line of poles down each street or alley. |> |> |> |> Again, where do you see 3-phase on every pole? |> | |> | Illinois, New York, Vermont (haven't looked here in OH). |> |> Maybe you should. You'll find a LOT of 208Y/120, some 480Y/277 (larger |> buildings), and maybe some leftover 240D/120, as well as single phase |> service in 240/120. But do take your camera if you are convinced there |> are some "6 star" services around. | | They surely wouldn't be called that because it's a stupid idea.
I don't know what they would call it if they provided it. That name is one I made up just to have a way to refer to it until someone picks or reveals a better or already used name. You're the one that says it is already deployed; so you tell me what they call it in your area.
|> |> Tell us some places. |> |> Even when there are 3 phases, do the transformers occur in groups of 3? |> | |> | Sure. |> |> And how many lugs on each are wired up? Does each transformer have the |> same number of MV bushings (whether that be 1 each or 2 each)? | | Never climbed a pole, but all three phases are used for Edison 240V | service. How may lugs is that?
That depends on the exact service. In the typical case there are three transformers forming a closed delta. The primary transformer will have 3 lugs used. This transformer has a 120/240 volt secondary and provides the source of 120 volts. The other 2 transformers are wired to other phases on their primary, and have 2 lugs used at 240 volts. One is wired between one end lug of the first transformer and the high leg. The other is wired from the high leg to the other end lug of the first transformer forming the delta loop. The 2nd 2 transformers are not grounded. They may have (probably do have) an unused center tap lug. A total of 4 wires come off this setup to the service drop in question. These are the three phases plus the neutral from the center tap which is grounded.
Other cases might be 240 volt delta without any Edison, or an Edison service that has no three phase at all.
|> |> Or do you mostly get one transformer per pole, tapping only one of the |> |> 3-phase MV lines? (That's what I see when there does happen to be |> |> 3-phase distribution). |> | |> | One pig per pole, three wires going between poles, under the MV |> | lines. |> |> That's single phase 240/120 of the Edison split phase variety. No three |> phase services there. | | Bullshit! The three wires were the three phases. You could see the | connections on the pigs.
If the service is three phase, they put the three transformers on the SAME pole.
Sure, you could form three phase service by splitting the transformers up on different poles and interconnecting the secondaries between poles. In the extreme case, the middle pole could be getting 120/240 from one phase one an adjacent pole, and 120/240 from the other phase at the other pole, and merge them to have the full "6 star" at the middle pole. But is that actually wired that way for any service drop? The service drop would have 7 (SEVEN) wires if so.
|> Look for cases of THREE transformers, each with the same number of MV |> bushings (either all have 1 or all have 2 each), and at least 3 LV lugs |> connected on all three. If only 2 lugs are connected on all three, then |> you have a wye system, usually 208Y/120 but 480Y/277 is possible (600Y/347 |> is very rare except in Canada). If 2 lugs are connected on 2 transformers |> and 3 lugs are connected on one transformer, it is probably 240D/120. | | Exactly!
But that's not "6 star" at all.
|> Other possibilities also exist. Be sure to get a number of photos at many |> different angles to get an unambiguous view of exactly how all the wires |> are connected. If you see one with 3 lugs connected on each of 3 separate |> transformers, where the middle lugs of each are connected together, and |> all the outer lugs, plus the joined middle lugs as one wire, supply 7 wires |> into whatever building is served, then be sure to get a LOT of photos. | | I'm not in the business of supplying your curiosity.
No, you are in the business of not knowing the difference between differnt kinds of three phase service configurations.
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----------------------------
writes:

----------------- There are many places where a single phase is run down an alley (the next alley is on another phase so that the total district load is pretty well balanced across the 3 phases. This is true in residential districts in many cities which exceed 1,000,000 inhabitants. Simply a matter of economics in situations where high heating or, more likely, cooling electrical demands are not present. Where I am, a 3 phase main feeder is across the street but a single phase feed from this line serves the whole of a small subdivision. There is simply no need for running 3 phases (particularly underground) as loads don't warrant it in this case. In a previous home, 3 phase was down the alley but only because there was a commercial load at the end of the street which warranted the 3 phase feeder.
There is no "one size fits all" solution so no BS is involved-just different observations in different places.
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Even the purely residential area I grew up in had all three phases on the pole (one pig per pole - four houses per pole).

Everywhere I've looked but *very* rural areas has three phase distribution.
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| Even the purely residential area I grew up in had all three phases | on the pole (one pig per pole - four houses per pole).
One house I lived in a long time ago had only single phase MV on it. Another around the corner (after we moved) had three phase MV on it. One pole pig served 3 homes single phase. The three phase then ran on down the street and branched off to a school which had three very large pole pigs. I went to grade school there and by 5th grade knew that was for three phase power (but I didn't yet know the difference between delta and wye).
Where I live now has a single phase MV branch running down about 6 poles and then goes underground to serve 3 pad mounts. It comes off a three phase MV trunk that goes to a college about 4 miles north.
If I wanted three phase power here, it would be VERY expensive to get.
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|> |> >Look again (open your eyes this time). You're not seeing the forest |> >for the trees. It *IS* on top of 90% of the poles in the country. |> >The other 10% are single phase only, generally found only in rural |> >areas. |> |> Really? | | Really! | |> In all of the places I've lived, residential areas had |> single-phase service only: a single MV line running down the top of the |> poles along the street or alley, and single-phase transformers |> providing center-tapped 120/240 service to several houses per |> transformer. | | Where do you live, Mongolia? The only places I've seen single phase | distribution is in the middle of the country (rural Vermont, in | fact).
MV comes out of substations in three phase. The distribution trunks are three phase. But many side branches, particularly residential areas, are single phase MV. So everyone on the same street is on the same phase. Big deal. The utility saves money doing that and can keep things in balance by putting the next street on a different phase.
|> Three-phase distribution is used for large customers |> only. | | Bullshit!
Of course in the distribution design, three phase goes all over the place because there might be scattered need for three phase. And then they have to keep it reasonably balanced where it does go, so the single phase lines branching off or going to a direct service are balanced over these phases.
|> Given the amount of area covered by single-family houses |> compared to the area used by commercial/industrial/large residential |> (high rise), I'd have to guess that more than 50% of the total number |> of poles that have any transformers carry one single-phase |> transformer. | | Your *guess* is wrong.
Actually this is quite common. Even if three phase distribution goes through a residential area, the transformers on the poles for homes along the way are usually just one transformer supplying one phase to that bunch of homes.
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snipped-for-privacy@ipal.net writes:

Different utilities in different areas have different practices, including the willingness to bring three phase down a street that doesn't need it yet, or will never need it.
I grew up in a large subdivision. Three phase went in at 3 points, but all the streets not on the roads the three phase followed were fed single phase. The single phase loads were approximately balanced, but some of them were not trivial. One single phase fed my longish street plus 3 shorter streets, a total of 9-10 pole pigs with 5-6 houses per transformer. There was a single three phase load, a clubhouse/golf course.
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