OT Electrical Question

[BigBoy1]

I just returned from a trip to Europe and the power there started be thinking. Why does North America use the 110 volt, 60 cycle as standard household power while in Europe, they have 220 volt, 50 cycle? Is there some scientific or technical reason why the two are different or is is something like, "I'll make mine different because I want to"? Inquiring minds would like to know.

[ogre]

Im not a certified electrician but i know 220 uses less amps. Someone told me since 220 pulls less amps that it saved money compared to 110. Then i read somewhere(popular mechanics) that that is false. So i dunno whos right anymore but if it does pull less amps and save money then thats my guess..

[MaxHeadRoom]

The 1ph domestic supply is also derived slightly differently, in N.A. the domestic supply is derived from a 120-0-120v centre tap 1ph transformer, where the 0 tap is the grounded neutral, in Europe where it is 220/240v 1ph, it is derived from a 3 phase transformer, 1 phase and the star (grounded) neutral.
Another difference is that in N.A. the neutral is re-referenced to ground at the service panel, in much of Europe, the neutral is grounded at the source only.
The reason for 240v in Europe cannot really be the load demand issue, as early domestic installations did not have large appliances as is the norm today, much of first installations were for electric lighting to replace piped gas lamp systems.
The same load on 240 and 120 is the same wattage, just lower current on 240. No money saving, just wire diameter is smaller on 240 for the same load requirements.
Max.

[SteveF]

You got me curious so I did a little searching on the Internet and the answers as to why are all over the place.

When I get the flux capacitor fixed in my DeLorean I'll go have dinner with Tesla, Edison and Westinghouse and get the real story.

Steve

[armedandsafe]

...wire diameter is smaller on 240 for the same load requirements.

That is the primary advantage of 220 single phase over 110. Cuts the cost of delivery systems by as much as 1/3.

Pops

[The Artful Bodger]

110 volts or 220 volts, 50 or 60 Hertz? Probably for the same reason that some countries drive on the wrong side of the road.

One advantage of 60Hz may be that there is less iron required in transformers and motors etc?

[The Artful Bodger]

The 1ph domestic supply is also derived slightly differently, in N.A. the domestic supply is derived from a 120-0-120v centre tap 1ph transformer, where the 0 tap is the grounded neutral, in Europe where it is 220/240v 1ph, it is derived from a 3 phase transformer, 1 phase and the star (grounded) neutral.
Another difference is that in N.A. the neutral is re-referenced to ground at the service panel, in much of Europe, the neutral is grounded at the source only..

Max, I have only vague knowledge of North American practices (except I note the cord on the motel toaster gets really hot if not fully unrolled). This 120-0-120 transformer, is that across one phase of the distributed 3 phases? What happens to neutral of the distribution transformer is that grounded (or maybe they are delta transformers?)?

[customcutter]

I always heard the electricians at work say that 220 volts would knock you off of it if you happened to get on it. 110 volts would cause the muscle to contract and you would be locked onto it. I've been on 110 US and 220 UK, both hurt.

I also used to tell the electricians at work that I don't like messing with electricity cause you can't see it, and when you do it's too late. Especially when a lot of our work was 4160 volts.

Ken

[J Tiers]

Max, I have only vague knowledge of North American practices (except I note the cord on the motel toaster gets really hot if not fully unrolled). This 120-0-120 transformer, is that across one phase of the distributed 3 phases? What happens to neutral of the distribution transformer is that grounded (or maybe they are delta transformers?)?

there are a number of systems of local power, depending on usage.

Houses, usually 120V, which is 120-0-120. It is usually obtained thru a transformer from a local 4160V 3 phase line (or one phase of such a line run up a street), most often from line to neutral on the primary. Secondary is the 120-0-120, which is grounded on the "0" line (neutral).

Large apartments.... usually supplied with 120Y/208 3 phase, two lines of which go to each apartment with neutral. That gives 208V between lines, and 120V each line to neutral.

Industrial.... Often 277Y/480V 3 phase, giving 277V to neutral, which can be used for lighting. Office 120V comes through a transformer, most often 208V 3 phase.

Some light industrial can have the same 120Y/208 service as an apartment. We have that at work.

Other industrial include 240V "wild leg" 3 phase, which has the 120-0-120 from one pair of wires, and the 3rd wire is the "high, or "wild" leg, since it is a higher voltage to the 120V neutral. Often found on farms, it supplies lights and office loads as well as 240 3 phase.

240V and 480V "corner grounded" systems are no longer put in, but still exist... these are delta systems with one of the phase wires grounded.

regardless of system, the common voltages are 120/240, 120/208, and 277/480.

[lakeside53]

That is the primary advantage of 220 single phase over 110. Cuts the cost of delivery systems by as much as 1/3.

Pops

But... it's not delivered any distance at 120 or 240. For residential, your local pole of ground transformer is fed with high voltage distribution. There are more distribuation losses with 60hz than 50 (think of long transmission lines as capacitors to ground).

In Japan the outlet voltage is 100 or 200, 50hz in part of the county, 60hz in the other.

Why 60 verse 50, 120 verses 240? Historical, and first to market.

[kf2qd]

And 60 Hz is considered to be more dangerous than is 50Hz. The human body seems to lock on 60Hz more than it does on 50Hz. Some military system use 400Hz. Smaller transformers and considered less likely for a human to lock onto 400Hz.

[J Tiers]

And 60 Hz is considered to be more dangerous than is 50Hz. The human body seems to lock on 60Hz more than it does on 50Hz.

Maybe, maybe not..... A low enough frequency will cause you to jerk in time to it..... and more of it goes deep into you*. The higher frequencies get past the speed at which you can react...causing a general muscle tightening.... so likely 50 OR 60 will cause "lock-on" if the situation is favorable to it....

Bottom line is that ANY of the common power voltages and frequencies can kill you. The relative ease with which they do kill you is not particularly interesting compared with the far more profitable concept of staying totally out of contact with ANY of them...........

One of the problems with the much touted 42V auto electrics was the fact that 42V (really 52V or more under charge) was above the UL and CE limits for "nominally non-hazardous" voltage.... meaning that it would have to be treated essentially just like household 120V or 230V. Naturally with 300V electric vehicles, that's a given, but with ordinary automotive stuff that "Bubba" will try to fix, it isn't so good.

* people are so resistive that the "skin effect" is not nearly as obvious as it would be with copper or aluminum.... but there is still some effect. So high frequencies will tend to go on your skin, low frequencies and DC will go deep. The limits of "low" and "high" may vary a bit depending on your particular case.

basically, just stay out of the wall outlet....... don't be thinking that 50 Hz may not kill you as dead as 60 or any other frequency. If you get zapped and don't die, you know (or ought to know) who to thank.....

[Paul Alciatore]

To answer the original question, I think you have to go back to the beginnings. Please correct me if I am wrong, but in the USA Edison and Westinghouse were fighting to have their power systems become the standard. Westinghouse wanted AC power and I believe he started with 110 or 115 Volts and 60 Hz. Edison was trying to standardize DC power which had considerable distribution problems. One of Edison's reasons for DC was that it was safer: he even argued that AC power was used for executions by electrocution. He argued that AC was more effective for killing people and his DC system was safer. I am sure that these arguments were not completely dismissed by Westinghouse. That may be part of the reason for keeping the distribution Voltage somewhat lower. It would allow Westinghouse to argue that his system was at least somewhat safer.

I am sure that power distribution in Europe and other areas of the world proceeded along different lines in those areas. Without the presence of Edison arguing against the deadly AC system, they were probably freer to develop the systems for greater the efficiency allowed by higher distribution Voltage.

I am not sure about the timing of the construction of electric distribution networks in every nation, however, I suspect that many of them lagged that development in the US and therefore had better advantage of hindsight. Also less democratic conditions may have made it easier to use higher and potentially more dangerous distribution Voltages.

As for the 50/60 Hertz thing, I doubt that it makes any great differences in the costs of transformers. In fact, a 50 Hz, 220 Volt transformer may be lighter than a 60 Hz, 110 Volt one. The mass of steel needed in the core is inversely proportional to the frequency so 60 Hz has a small advantage there, BUT it is also directly proportional to the current and for the same delivered power, 110 Volt circuits need twice as much current and ashamedly twice as much metal in the core.

OK, some of the above is not completely true in the present forms of power distribution in the US vs Europe. In reality, homes and small businesses in both areas have 220 Volt service to the building. If you are in the US, look at the power feed from the pole to your house. You will see three black wires coming in - ignore the uninsulated steel cable they are wrapped around as it is just for mechanical support. One of these three wires is a ground and the other two are hots. Each hot is 110 Volts above ground and they are 180 degrees opposite in phase from each other so the Voltage between them is 220 Volts. It is only at the power panel where individual 110 V circuits are broken out.

The fact that both of these hots are only 110 V above ground does make this system a bit safer than one where a hot wire is 220 V above ground. I don't know if this is the way European circuits are constructed, so please inform me and the others here.

However, I doubt that this fact negates my original arguments about safety as things are evolved a lot from the time when these things were first created and it was conditions then, not now that determined what we are still using today. It is the history, not present day best engineering practice that was the determining factor here.

[darryl]

An interesting read on the subject-

History

[MaxHeadRoom]

If you are in the US, look at the power feed from the pole to your house. You will see three black wires coming in - ignore the uninsulated steel cable they are wrapped around as it is just for mechanical support. One of these three wires is a ground and the other two are hots. Each hot is 110 Volts above ground and they are 180 degrees opposite in phase from each other so the Voltage between them is 220 Volts. It is only at the power panel where individual 110 V circuits are broken out.
.

Technically it is not a termed a ground as it cannot be used as a ground conductor, it has to be re-referenced to ground at the service panel and then the ground and neutral are considered separate conductors.
In Europe and also I believe Australia the neutral is not re-referenced to ground at the panel, only at the source.
This means that a required ground resistance from building ground conductor or ground rods back to the transformer grounded star point conforms to a sufficiently low resistance level.
Otherwise a main GFI or similar unit is used at the main panel for the whole service.
Most of the rest of the world uses one phase of a 3 phase transformer with the star point grounded as a neutral.

Max.