# US system is not as inefficient as I once thought

I've known for some time now that the Europeans use 230 volts and that we Americans use 120 volts for most household items and 240 volts for large
appliances. Even though I've never really given it much thought, I've always imagined that the US system is somewhat less efficient than the European system because of the lower voltage and higher amperages that our electrical devices have use to compensate for the lower voltage. But I was talking to an electrician the other day and he told me that this is not really the case between the breaker box and the transformer. According to him, if all the 120 volt loads that are connected to one hot leg exactly matched the loads that are connected to the other, it would be as if half the loads were connected in series with the other half. At the same time, you would find that the neutral is not carrying any current at all. In the real world, some of the current does have to pass through the neutral since the loads being imposed on both legs are not perfectly balanced. But most of the current that's delivered to our homes comes as 240 volts through the hot wires because of this effect. This would also explain why a double receptacle circuit with a shared neutral wire doesn't have to use a neutral wire that can accommodate the amperages of both 120 volt hot wires.
Robert
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So.. what about all that extra copper you have to run to get *two* hot wires?.. How does that make it more "efficient"?? All it does is give you more choice..
Cameron:-)
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You could probably balance that with the extra secondary copper European countries use with their central transformers serving a bunch of customers. Usually a US customer has the pole pig serving them on the right of way in front of their home. Typically a transformer only serves 2 or 3 homes, within 50-100 feet of the pole. Street distribution will be a big voltage.
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I imagine that this is only partly true. But I wonder if any European has ever thought that they could make their own electrical services better and more efficient by using two 230 volt legs with 460 volts between legs. A breaker box using this system could be wired up exactly like an American breaker box except that individual circuits would use 230 volts instead 120.
Robert
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I dunno about the Europeans, but 2-phase power (or 3-phase if you really want it) is readily available over here from the 440V 3-phase running down the street.
Some older houses use 2-phase for electric hot water or stove/oven units, but most houses use only single-phase so that is all they get connected. Many people use 3-phase in their garages to run welders/air-compressors and the like.
Does that make the Aussie system better than the Yankee system?? Surely not.. ;-)
Cameron:-)
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It might. But the best system doesn't exist anywhere as far as I know. I've always entertained the idea of just ditching the final step-down transformer completely and running the 4,000 or 5,000 volts directly into the appliances and other household loads. Obviously, all the circuit breakers would have to be GFCI protected to make such a system safe. And, of course, all manufacturers of 120/240 volt devices would have to adapt their products. But this would be quite a bit less expensive than the big fat wires that we have to use right now to carry high amperages. If a 5,000 volt service was supplying your house with electricity, the electrical wire that enters your house wouldn't be much bigger than your telephone wire.
Robert
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The electrical wire that enters your house might not be much bigger than your telephone wire, but the insulation surrounding it certainly would!!
The biggest problem with your idea is the voltage potential:
1. Appliance manufacturers would need to design their gear with larger arc gaps between the supply and the surrounding gear - hence everything would become larger and more expensive.
2. The distance that the arc could jump would require a complete re-design of *everything* between your power pole and your TV set (including the TV set! ;-).
Hardly the best system..
Cameron:-)
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Yet. I'm working on inventing wireless electricity. ;-)
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I read in sci.engr.electrical.compliance that Matt
127463.news.uni-berlin.de>) about 'US system is not as inefficient as I once thought', on Tue, 30 Sep 2003:

Tesla and Yagi were there before you!
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
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On Tue, 30 Sep 2003 02:32:50 -0400, "Robert Calvert"

It is difficult to say which is the 'better' system. Internationally practice has tended towards North American 120/240 volt (with 440-600v or so for industrial loads) and European 230/400 volt. Each system has its good points and its weak points and everyone tends to be comfortable with the system they are used to. There imperatives that applied in the past (eg co-ordination with long distance open wire telephone circuits).
It is rather like two department stores in a city I know. One is 'up marhet' and the other one 'average market' (the history of this one is quite amazing). The then Managing Director of the up market store refused to be drawn on a comparison but merely stated that they were founded in entirely different circumstances. Discussion of voltage systems would be similar.
I doubt that there is any advantage going above 250/433 volts for general use. A higher frequency may be of some advantage for transformer design and because any induction or radiation effects might do less damage (indeed if this is significant in any case) to the body at say 80Hz.
I have previously wondered about an 'intermediate' voltage for lower density developments (with long services to residences) where underground reticulation is mandatory. A 11,000/230 volt transformer (fed by two phases - no HV neutral) at each house, cabling and fuses would be expensive, but a 1,000 volt scheme could be viable especially as it could use standard LV reticulation and service cable. However as 'off the shelf' transformers for this use would not have been available, I gave this away without too much further thought.
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I read in sci.engr.electrical.compliance that Peter
et.nz>) about 'US system is not as inefficient as I once thought', on Sun, 5 Oct 2003:

A higher frequency that 60 Hz might be OK for wholly overhead distribution, but the capacitance of underground cables is large and causes significant loss even at 60 Hz.

I believe the US used to use 4 kV for street-level distribution but demand has resulted in the voltage being progressively increased.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
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But a limiting factor in many transmission line loads is the reactance of the line. I^2R heating is not always the limiting factor.
Raising the freq. to 80 would make this worse. The total power than could be delivered over a line would correspondingly drop. Not sure if savings in transformer costs would offset the change in transmission capacity.
daestrom
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I heard that Eurpoean vacume cleaners for homes are much more powerful than American ones. In USA, the 120V, 15A circuit breaker limits a useful appliance to 1440 watts (about 12 amps at 120VAC). With 230VAC (assuming same 12 amps), twice more powerful appliances can be used without having to install the expensive 30 circuits (in USA, washing machines, cloth dryers, electric ranges that use 240V and/or 30 amp circuits are pre-wired in the utility room or kitchen for that reason). It would be nice to be able to run a powerful 230V, 15 amp machine from each electric socket (for example, a powerful window mounted air conditioner, high-speed color copier, or 3000 watt bathroom heater after taking a shower on a cold winter morning). The most exciting & useful product would be a 3600 watt hair dryer that gurantees "15 seconds to dry your hair or your money back !!!"
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I guess that is why "powerful" window shakers come with a NEMA 6-15 (230v) plug on them. There is absolutely no reason why you can't have 230v on every wall. It just doesn't seem that necessary.
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On 5 Oct 2003 13:26:13 -0700, snipped-for-privacy@tsipower.com (Nam Paik) wrote:

More like 10 amps (Australia & NZ) and 13 amps (UK) for standard outlets. Still 2300 watts is better than 1440 watts.
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(Nam Paik) wrote:

15 amp outlets are available in Oz/NZ if you need them (dryers/dishwashers and the like) - the only difference is larger earth pin.
Cameron:-)
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On Mon, 6 Oct 2003 12:12:52 +1000, "Cameron Dorrough"

Correct - I omitted this aspect for brevity as 10 amp outlets remain the usual type.
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Kitchen and laundry rooms contain 20A circuits wired with 12 AWG wire (4mm^2) as opposed to the normal 15A with 14 AWG wire (2.5mm^2). There is usually a dedicated circuit for the washer, and two or more general purpose circuits for the kitchen. This increases the power to 1920W continuous / 2.4kW intermittent. (US code allows for 100% of rated draw for intermittent appliances). When wired for electric clothes dryers, the utility room will have a dedicated circuit of 30A 120/240V. The norm is for the dryer to use a 120V drum motor and timer and 240V elements. When wired for electric ranges, stove tops or ovens, dedicated 120/240 circuits of either 40A or 50A are provided. For gas appliances, 120V general purpose outlets are used. AFAIK, the only application for 30A 120V circuits is for small to medium sized recreational vehicles. The larger recreational vehicles use 50A 120/240V

Window / through wall air conditioners with a load under 1440 VA generally use Nema 5-15 (15A 120V plugs). Good for nice, big light dips at startup. Between 1440VA and 1920VA it's a tossup whether they are 120V or 240V. Above 1920VA they are pretty much all 240V. A major design constraint for products like copiers is to get the draw under 1440VA. Light dips on copiers are also much more noticeable when the copier / laser printer starts up. Making them less than 1440VA is an indirect way to force efficiency! (Don't tell me the Americans don't care about efficiency, we can make copiers run on less power than in the EU, and we don't use 3kW bathroom heaters!) ;-)
Matthew
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Plug in a North American vacuum into a EU outlet, and it's much more powerful than the EU one for a few seconds.
The flames that follow are a bummer on the other hand.
;-)
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I've noticed that 240 volt window air conditioners are rapidly becoming obsolete. Back in the 1970s, it was pretty much a given that all 17,500 BTU air conditioners ran off of 240 volts. But several days ago, I happened to notice a 17,500 BTU window air conditioner at Wal-mart that can run off a standard 120 volt receptacle. With an EER of 11, I suppose it's not hard to see why. If you look through some of these newsgroups, a post will crop up from time to time asking how to convert a 240 volt air conditioner receptacle into a 120 volt one. I suppose times are changing for window air conditioners. Although, I'm sure that central air conditioners will remain 240 volt for some time to come.
Robert
BTW how do you Europeans measure the capacity of air conditioners anyway? Since the BTU is defined as the amount of heat needed to raise the temperature of one pound of water one degree Fahrenheit, I'm assuming that such a measurement is not used in Europe. Do you judge your air conditioners by the calorie?