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  1. #21
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    Quote Originally Posted by thermite View Post
    Do yah now? I would not. Separate single-phase service branch, rather. Better-yet, avoid the need by staying at 2XX VAC, ELSE drop to 24 VAC off a transformer for controls & c.

    1XX VAC is referred to just WHAT in a Delta service?

    "It depends" yah?

    Why d'you think I "voted" with my bankbook to provide Wye service and a re-derived "local" Neutral that is always at equal-potential, ANY hot leg above Neutral OR PE? HIGHER than the usual 120, yes. But at least all are the same or near-as-dammit ("generated leg", etc. applies..), there's no "corner grounded Delta", hence no "high leg" nor "stinger".

    Nether of an RPC nor a Phase-Perfect - naturally "Delta" output, the both of them - is otherwise predictable for that, all legs, nor meant to be directly utilized that way for 1XX loads.

    If you need 1XX, single-phase off a 3-P Delta service?

    Proper way to provide it is with a 240:120 full-isolation transformer inside the envelope of the served "system". Keep in mind the secondary will be floating, not PE/ground nor Neutral referred, either.

    ELSE a Delta transformer as has a "lighting" tap for such needs OUTSIDE the end-Luser equipment demarc.

    Which is not the same as "full" Wye, be it 208 or higher.
    Well, you're not wrong, but it is uncommon to separate single phase loads from 3 phase ones today. In Europe, almost all modern power feeds are 5 wire regardless if the 3 phase load is wye or delta. I suspect the reason is cost reduction (elimination of control transformers), convenience and temptation reduction by using safety earth as a return path. After all, there is no electrical reason not to include a neutral line at a service point. If you don't need it, no problem, don't use it. Now, there maybe reasons to separate these services as described by Thermite when the 3 phase is derived, but not if the 3 Phase service is delivered off the street. I feel so sorry for all you Americans that do not have 3 phase service. In Europe, it is exactly the other way around. Very few homes do not have a 3 phase service. My home, built in the 1930's, has a 32 amp service off the street. All new homes are built with a 64 amp 230/400 Volt service as a norm. The higher power services are to support geothermal/solar systems and electric car recharging stations. America, in this respect, is way behind Europe.

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    Quote Originally Posted by steve-l View Post
    Well, you're not wrong, but it is uncommon to separate single phase loads from 3 phase ones today. In Europe, almost all modern power feeds are 5 wire regardless if the 3 phase load is wye or delta. I suspect the reason is cost reduction (elimination of control transformers), convenience and temptation reduction by using safety earth as a return path. After all, there is no electrical reason not to include a neutral line at a service point. If you don't need it, no problem, don't use it. Now, there maybe reasons to separate these services as described by Thermite when the 3 phase is derived, but not if the 3 Phase service is delivered off the street. I feel so sorry for all you Americans that do not have 3 phase service. In Europe, it is exactly the other way around. Very few homes do not have a 3 phase service. My home, built in the 1930's, has a 32 amp service off the street. All new homes are built with a 64 amp 230/400 Volt service as a norm. The higher power services are to support geothermal/solar systems and electric car recharging stations. America, in this respect, is way behind Europe.
    Ummh.. "Global" dominant-carrier telco pensioner with homes in Hong Kong and mainland China as well as the USA? None of this is news.

    We could WISH we had 3-Phase to the residences here, too.

    But we do not.

    OTOH? We provide easily double the POWER to an average residence - which is typically 50 to 100 percent more spacious and MORE than four times as distant from the grid - and cheaply so, one wire saved times billions of total miles not run.

    Distance drives a LOT of historical wiring choices, USA.

    I once had the same disjoint with UK Telco Engineers railing over why the USA stuck with DS1/T1 over twisted-pair instead of E1 over coax.

    "Yah, mate but how far do you have to RUN it?" I asked.

    Silly short distances, as it turned out, the UK being about the size of New York State but more densely populated than mainland China's average.

    We, OTOH, could - and DID run - "T1" (and "T2", even if only for NORAD!) by the hundreds of miles, given it was designed to run cross country on already-paid for copper pairs - or even aerial open-wire if and where it had to do.

    Back when the C&W US unit made a bizness of serving smallholders in both towers of the old World Trade Centre off a shared full-featured uber-PABX in one of the basements? Dominant Carrier blocked us from pulling new wire.

    BFD.

    We order-up raw McCullough Loop Burglar / Fire Alarm circuits off their own tariffs - then put T1 onto them - covered both towers!



    Swings and roundabouts.



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    I'm speechless- please continue!

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    Quote Originally Posted by Dan from Oakland View Post
    I'm speechless- please continue!
    LOL! Californios most of all might go apoplectic they but knew a HUGE part of the "Cold War" defence establishment was funded off the back of higher prices for US & European postage stamps, BT, C&W, the continental PTT's, and Ma Bell especially all-hands monthly telephone bills .....so it didn't have to show up as Congressional appropriations ... and far more VISIBLE and contentious TAXES to be argued over for scores of years!

    Nine thousand miles of Ma Bell's "T2" - trenched and "hardened", to link 26 SAGE air-battle 'puters alone?

    Blame those "600 dollar toilet seats", but the job got done, and waaay faster than any 'Hoovermint" agency ever cudda dood it.

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    Quote Originally Posted by thermite View Post
    .....

    1XX VAC is referred to just WHAT in a Delta service?

    ......
    Secondary is referenced to ground one of three ways.... because the NEC requires it for a branch circuit.

    corner grounding ("deprecated", i.e. the powerco does not install it anymore)...but you get 230V to neutral from that

    or a wye secondary with the wye point grounded (you get about 139V wye from a 230/240 delta, not very useful)

    or high leg 3 phase, which has two 120V legs intended for 120V use. Neutral is useful with this.

    Also possibility of 208V that may be just "called" 220V, which is of course 120V from neutral to any phase wire (but is not actual 220, 230 etc, it is 208V delta).

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    For Delta three phase you have a 4 wire service with three hots and one neutral. The "A" and "C" phases are each 120volt to ground with the "B" phase (or 'high' leg) being 208 to ground. However all three are 240 volts when referenced between any two phases. So the high leg is typically an orange conductor or marked as such and enters the meter as the 3rd leg (per utility requirements which can vary) and then wired as the center pole phase in the panel board (breaker box if you prefer). Any circuit that is 120 volt or 240 volt single phase that uses a neutral should use the A and/or C phases. If a single phase device is 220 only (so no neutral!) then you can use any two phases for that circuit. High leg is great for 3 phase gear but if you have lots of single phase phase loads (like an office building etc) then 208 WYE is a better choice since if can better handle balance the 120 volt circuits.

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    Quote Originally Posted by JST View Post
    Secondary is referenced to ground one of three ways.... because the NEC requires it for a branch circuit.

    corner grounding ("deprecated", i.e. the powerco does not install it anymore)...
    Neither will I.

    Which was the whole point. And very nearly the ONLY point... of my spending the actually modest extra coin. Fat inductance of the Delta-Wye transformer doing a final ration of smoothing of a P-P output is nice as well.

    The "real" goal was and is lowering risk of lethality, however modestly.

    See also the growing trend, globally, to require 2XX service on construction sites to be stepped-down to 120-0-120 with portable and weather-sealed center-tapped & Earthed transformers. Better-yet? 50 or 60-0-50 or 60, with the power tools across the outer"hots' and any leg to mud-legs and feet even lower risk. Plenty of 100 V & 120 V market corded tools, after all.

    Nobody had seemed to MIND electrocutiong a few worker-bees every year all over Asia & such. Not until the needed skill levels had gone up to where it was harder to replace the dead and maimed ones.



    "The Code" has a LOT of seldom-noticed stuff in it, BTW.

    Including provisioning of a safety Earthing via inductive, capacitive, or resistive paths - not just "best wire" or go without power altogether.

    After all - "NFPA" has been gradually evolving, HOPEFULLY improving, fire and safety code sometimes having had to be satisfied with "best we could get, under the prevailing circumstances" so long as better than nothing where "perfect" wasn't always possible.

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    Quote Originally Posted by thermite View Post
    Ummh.. "Global" dominant-carrier telco pensioner with homes in Hong Kong and mainland China as well as the USA? None of this is news.

    We could WISH we had 3-Phase to the residences here, too.

    But we do not.

    OTOH? We provide easily double the POWER to an average residence - which is typically 50 to 100 percent more spacious and MORE than four times as distant from the grid - and cheaply so, one wire saved times billions of total miles not run.

    Distance drives a LOT of historical wiring choices, USA.

    I once had the same disjoint with UK Telco Engineers railing over why the USA stuck with DS1/T1 over twisted-pair instead of E1 over coax.

    "Yah, mate but how far do you have to RUN it?" I asked.

    Silly short distances, as it turned out, the UK being about the size of New York State but more densely populated than mainland China's average.

    We, OTOH, could - and DID run - "T1" (and "T2", even if only for NORAD!) by the hundreds of miles, given it was designed to run cross country on already-paid for copper pairs - or even aerial open-wire if and where it had to do.

    Back when the C&W US unit made a bizness of serving smallholders in both towers of the old World Trade Centre off a shared full-featured uber-PABX in one of the basements? Dominant Carrier blocked us from pulling new wire.

    BFD.

    We order-up raw McCullough Loop Burglar / Fire Alarm circuits off their own tariffs - then put T1 onto them - covered both towers!



    Swings and roundabouts.


    I think some of that is a bit short-sighted. If we (NZ) want to take a fair bit of power to a house, 63A 400V (45kVA) is not uncommon. Yes, you need a fourth wire. But you're running 4x16mm copper, whereas 240V 200A (48kVA)? That's something like 3x 70mm CU. Each core has more copper than the whole cable we would run. Aluminium is also an option and has the same disadvantage.

    On top of that, if we want to push that 45-48kVA over long distances, a 400V 63A supply on 4x50mm will run 200m+, whereas a 240V 200A supply on that 70mm, with similar total copper? You're looking at 45m.

    There's a reason we can run 50+ houses per transformer.

    And if you want to start looking at *long* runs, you use SWER.

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    Quote Originally Posted by SomeoneSomewhere View Post
    I think some of that is a bit short-sighted.
    Depends. First of all, much as I prefer Copper, and have had three of my four residences RE-pulled from the pole or vault with it at premium cost, the major utility companies and the Aluminum producers did, eventually, sort both changes to the Alloy and to the installation techniques to make shiney-wood work, and work very well.

    The current home had an addition added about 35 years ago that required the 200 A 240 VAC "split phase" service entrance be relocated about 30 feet North. The pull is still fine, termination not needing touched, tightened, re-made, nor otherwise disturbed, and that's 4-ought Aluminium alloy 35+ years on and counting.

    The REST of the story is that the Voltages the other side of a vault or pole transformer are a great deal higher than subscriber side, and that isn't even a hundred feet away for each of four or so homes.

    Next-up, the primary of that transformer is in turn, further, but not all that far from higher Voltages, yet.

    And so on.

    Most of the differences actually greatest in that last run to the subscriber and one more.

    Far fewer differences as to "best current practice" in global grids as we go back UP those grids.

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    My comment about copper vs aluminium is more just saying that I'm aware you can use both, and I'm more familiar with sizing copper.

    Here, it's not unusual even in urban areas for the nearest transformer to be 200m away. You can't really do that with lower voltages as you've found.

    But yes, once you get to around the 33kV level, everything is all the same except for the different frequencies.

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    Quote Originally Posted by SomeoneSomewhere View Post
    My comment about copper vs aluminium is more just saying that I'm aware you can use both, and I'm more familiar with sizing copper.

    Here, it's not unusual even in urban areas for the nearest transformer to be 200m away. You can't really do that with lower voltages as you've found.

    But yes, once you get to around the 33kV level, everything is all the same except for the different frequencies.
    Didn't ever even try to do, AFAIK. North American grid was suited to the needs, Big Bang, onward.

    Both Canada and the Lower 48 had loong runs, sparse populations, and plenty more METAL than many other nations had cheap access to - or could afford at all.

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    brown orange yellow works for me

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    Fwiw ..
    3-phase power as in the EU as a std is actually cheaper in terms of copper and wire than the common US household power mixes are.

    440V 3-phase and 220V single phase being the norm, it´s either 1.4 times cheaper or 2 x cheaper than typical US power feeds.

    Neutrals are a bit rare in europe, mostly not used.
    (You have a bit of anything and everything, but it´s very minor).

    Typical is 3-phase 3 wire, plus safety ground, to every house.

    440V nominal, and 220V single phase derived from it throughtout the house.
    Typical is 2.5mm2 wire, 2 wires + gnd, cheap, small, easy to pull, good for about 3 kW.

    Upto 6 kW service single phase, but usually 3-4 kW max for bigger appliances, jacuzzis, saunas, ovens, single phase.
    6kW would be 56 Amps on a 110V line in the US, +/-, no ?


    In the EU, typical max/unit would be 32 amps for one GFI, about 6 kW, 220V.
    Single run line to the point of use, like an oven or sauna.

    If you double your voltage, your currents drop by 2x x 1.4, or about 3 times.
    IR squared losses in wire / power.
    If You use 3-phase, your efficiency goes up about 1.4 times, so your losses dorp about 1/1.4.

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    Quote Originally Posted by hanermo View Post
    Fwiw ..
    3-phase power as in the EU as a std is actually cheaper in terms of copper and wire than the common US household power mixes are.

    440V 3-phase and 220V single phase being the norm, it´s either 1.4 times cheaper or 2 x cheaper than typical US power feeds.

    Neutrals are a bit rare in europe, mostly not used.
    (You have a bit of anything and everything, but it´s very minor).

    Typical is 3-phase 3 wire, plus safety ground, to every house.

    440V nominal, and 220V single phase derived from it throughtout the house.
    Typical is 2.5mm2 wire, 2 wires + gnd, cheap, small, easy to pull, good for about 3 kW.

    Upto 6 kW service single phase, but usually 3-4 kW max for bigger appliances, jacuzzis, saunas, ovens, single phase.
    6kW would be 56 Amps on a 110V line in the US, +/-, no ?


    In the EU, typical max/unit would be 32 amps for one GFI, about 6 kW, 220V.
    Single run line to the point of use, like an oven or sauna.

    If you double your voltage, your currents drop by 2x x 1.4, or about 3 times.
    IR squared losses in wire / power.
    If You use 3-phase, your efficiency goes up about 1.4 times, so your losses dorp about 1/1.4.
    Nope, depending on where you are in Europe.

    You will not see 440V anywhere.

    Standard was previously 220/380V, but has been paper-increased to 230/400V to meet in the middle with the UK's historic 240/415V.

    With three phase, you need a neutral to 'derive' the single phase voltage. It's 1/sqrt(3) of the line voltage, not 1/2, as you're not dealing with centre-taps.

    Most smaller loads are single phase to neutral. Larger loads will be three phase but may or may not need a neutral. This mostly depends on whether they have lots of control equipment and smaller motors that need 230V. For example, an aircon unit is likely to have a neutral to run 230V fans, crankcase heaters, valves etc, whereas a saw or air compressor will not as it's all just large motors.

    I believe limited areas have 127/220V three phase, so 220V loads are connected line to line and the neutral is not distributed. This is quite rare and being phased out.

    Exactly how much power is available at each property and whether it's single or three phase will depend on the region and the size of the property. The UK likes fairly large single-phase feeds (e.g. 100A 230V, 23kVA), whereas 'most' of Europe is more likely to have 32A or 40A three phase as the smallest common supply.

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    Quote Originally Posted by hanermo View Post
    Fwiw ..
    3-phase power as in the EU as a std is actually cheaper in terms of copper and wire than the common US household power mixes are.
    Surely. But that is not a "3-Phase" issue. Of greater effect is that y'all don't mind running far more lethal Voltages right to the wall and end-Luser's fingertips, so the current WILL be lower and the wire smaller, according!

    North America was "metals rich", US & Canada had a greater shortage of useful humans than of metal, placed a higher value on human life, went for reduced risk of electrocution.

    Not a "phase-count" issue, even then. 240 split-phase, either of two legs to ground ~ 120 VAC. 208 Wye, any of three legs to ground, same again.

    Europe and Asia - Japan the exception, "last meter" being 100-120, similar safety- goals as US & Canada - were/are metals poor and people-crowded, did the reverse.

    Took the riskier but cheaper path.

    No foul.

    At least it is less NOISY than the endless wars with each other y'all USED TO rely-on to deal with a chronic surplus of pesky humans in need of pruning.

    Or it WAS less noisy 'til y'all started rationalizing it...


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    Quote Originally Posted by thermite View Post
    Surely. But that is not a "3-Phase" issue. Of greater effect is that y'all don't mind running far more lethal Voltages right to the wall and end-Luser's fingertips, so the current WILL be lower and the wire smaller, according!

    North America was "metals rich", US & Canada had a greater shortage of useful humans than of metal, placed a higher value on human life, went for reduced risk of electrocution.

    Not a "phase-count" issue, even then. 240 split-phase, either of two legs to ground ~ 120 VAC. 208 Wye, any of three legs to ground, same again.

    Europe and Asia - Japan the exception, "last meter" being 100-120, similar safety- goals as US & Canada - were/are metals poor and people-crowded, did the reverse.

    Took the riskier but cheaper path.

    No foul.

    At least it is less NOISY than the endless wars with each other y'all USED TO rely-on to deal with a chronic surplus of pesky humans in need of pruning.

    Or it WAS less noisy 'til y'all started rationalizing it...

    Yeah, that's a volts-to-ground thing.

    I can't find anything actually measuring the difference in lethality, though - I guess it's a bit hard to get ethics approval.

    But then we go and make good decisions that you guys... don't.

    The insides of our switchboard, light switches, and sockets are built so that you can't just touch live parts or have them touch each other or earth. I still don't understand how you can have bare earth wires floating around, next to bare hot busbars, and everyone thinks this is fine? Likewise with the screws sticking out the side of the sockets next to metal boxes... wrapping them in tape is literally a band-aid fix.

    We also don't have single insulated mains cable.

    Likewise, that dumb penny challenge to short out a plug? It doesn't work with any NZ/AU, UK, or EU plug made in at least the last 15 years. The possibility to do it was engineered out of existence by socket shrouds and insulated pins. That stops you shoving your fingers in there too.

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    Quote Originally Posted by SomeoneSomewhere View Post
    ........

    But then we go and make good decisions that you guys... don't.

    The insides of our switchboard, light switches, and sockets are built so that you can't just touch live parts or have them touch each other or earth. I still don't understand how you can have bare earth wires floating around, next to bare hot busbars, and everyone thinks this is fine? Likewise with the screws sticking out the side of the sockets next to metal boxes... wrapping them in tape is literally a band-aid fix.

    ..........
    Say WHAT?

    Take a look in a standard breaker box..... the hot buses are in the middle, blocked by insulation and the breakers. Neutral and ground go elsewhere around the outside. They also do not "float around".... although I suppose that a sufficiently bad workman could devise a mess that would indeed be dangerous.

    Even so, insulation of any wire in an enclosure must be rated for the highest voltage in the enclosure. And it is common for wires to have two layers of insulation, usually a thicker functional layer, and a thinner "wear" layer over that.

    Over a hundred years ago, things were different. No ground wires, but it would scare you to death to see a fusebox from around 1910 or so. Not a scrap of insulation in there, just heavy busbars in a grid, with fuses where they cross.

    And, screws do not generally "stick out" from outlets or switches, they are recessed in any modern socket or switch, to reduce the possibility of contact. You could push them up against the box side, and they will not make contact. But of course even if they did, the breaker would open immediately.

    The EU areas have had a habit of undersizing the neutral, and depending on "load diversity" to reduce neutral current. Worked kinda OK until computers and SMPS that did not draw current as expected, and the workaround was to require power factor correction/harmonic reduction in order to allow the neutral currents to cancel properly. The US has always required the neutral to be the same size as the non-grounded conductors.


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