US system is not as inefficient as I once thought

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:-)

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

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

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

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:-)

I read in sci.engr.electrical.compliance that Robert Calvert wrote (in ) about 'US system is not as inefficient as I once thought', on Tue, 30 Sep 2003:

The extra copper involved is your neutral. Your 'two hot wires' correspond to the European live and neutral.

The European distribution system is quite different from that in US. Power is distributed *extensively* as 3-phase 230/400 V. There may be

Converting a European distribution network to effectively a six-phase system would be vastly expensive, and there are serious safety issues with 460 V supplies in the home. One advantage of the 120 V supply is that a shock from it is not so likely to be fatal.

Hang on a sec.. Excuse my ignorance, but are you saying that there is no neutral in the US 120/240V system?

What's the return path? Ground??

Thanks, Cameron:-)

A bit of history as I understand it (corrections welcom!)

The US has 110 volts because the original light bulb (invented by Thomas Edison in the USA) ran on 110 volts DC, and when we converted to AC we kept that voltage so that everyone wouldn't have to buy new light bulbs.

Nicola Tesla (the genius) made careful calculations and measurements and decided that 240 volts at 60 Hz. was the best voltage and frequency for AC power.

Many European countries modified Tesla's 240 volts to 220 volts so that you could use two 110 volt bulbs in series, while in the US they changed the 110 volts to 120 volts so that two 120 volt bulbs in series would run on 240 volts.

The engineers who built the first generating facility in Europe decided that 60 Hz. didn't fit the metric standard unit sequence (1,2,5), so they insisted on 50 Hz. (Westinghouse was pushing 133 Hz at the time...)

One reference I checked says that 50 Hz is around 20% less effective in generation, 10 to 15% less efficient in transmission, and requires up to 30% larger windings and magnetic core materials in transformer construction. I believe that electric motors are also less efficient at 50 Hz, but don't quote me on that one - I am working from memory.

What I don't have is a reference that tells me whether the loss of efficiency from 50 Hz. is lager than the gain from

That would give you 230v to earth, which is a larger danger than 120V.

My home laboratory is wired with balanced 60v out of phase legs to hot and neutral. This greatly reduces electrical noise.

This supply type was used for some farms in the UK in the case where only a single phase HV supply was available to the final stepdown transformer. It would not be installed today, and it was never the preferred option AFAIK. Farm machinary was often available in 480V versions specifically for this supply type.

European has not though of this for the reason that three phase power feeding is here very typical way to distribute power. A typical electrical distirbution panel get in three phase power: three phase conductors and one neutral/ground.

There is 230V from one live to neutral. And 400V between two live wires.

In ideal three phase power where all single phase loads are similar the neutral current is zero. In case of not so evenly loaded loads, the neutral current is from zero to one phase current maximum.

Normal household loads are single phase. Large loads use three phase power.

This is well working and efficient way to distribute power.

I read in sci.engr.electrical.compliance that Cameron Dorrough wrote (in ) about 'US system is not as inefficient as I once thought', on Tue, 30 Sep 2003:

Of course there is. It is the neutral which is the extra conductor needed in the US system compared with the European single-phase system.

I don't know.. but I would love to go there for a few years or so to find out!

Anyone from down under wanna pay for a grant for a Yank to come and watch the electrons flow?

Pretty sure I could watch them from the beach most of the time! :o)

Yet. I'm working on inventing wireless electricity. ;-)

Technically you are correct, but in Europe we use 230/400V (three phases) which balances out in the same way. It saves even more on the wires than the center-tapped single phase.

(After the transformer, that is. Ahead of the transformer, with thousands of volts, it's an entirely different matter.)

/Clas-Henrik

Yeah, a #24 neutral! All I have to do to make toast is make sure the hair dryer is running on the other circut. Good observation.

The US system uses 600 volt wire, so the voltage could be upped if there is a need in the future to add more power. All 120 volt circuits could be converted to 240 volts without installing new wire.

Don't forget to factor in the efficiency gains for running large motor loads on 3 phase.

Question: Are appliances with large motors (refrigerators, etc.) available in a 3 phase, 400V option in Europe?