Naked Science Forum
Non Life Sciences => Technology => Topic started by: neilep on 17/08/2007 17:49:18
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Over here in the UK we use 220v...over there in the US you lot use 110v.
Does that mean our appliances use twice as much electricity ?
What is the advantages and disadvantages of 110 and 220 ?
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We use both. Things like our electric dryers use 220.
This I found at this site...
http://uk.answers.yahoo.com/question/index?qid=20070329180841AAq2kCe
C_Rock136
It's like what Charles said. You only need to use half the current for 220V (actually usually called 240 but sometimes called 220 and then 110 in the U.S.). P=IV is how much power is required to power an appliance or some sort of electric device. Say it requires a 1000W of power. In the U.S. the current would be I=1000W/120V =8.33 Amps
while over in Europe it would be 1000W/240V = 4.16 Amps
You can see how it requires half the current. 240V is much more dangerous so that might be a reason that the U.S. steps it down to 110. There are benefits either way. 110 has been known to kill a lot people though because it causes your muscles to contract if you come in to contact with 110 and you can't let go. 240V usually has enough voltage to just complete throw you if you were to touch it instead of forcing you to hold on like 110V would. So it is actually tough to say which one is more dangerous in that sense. I guess you could also ask the question of why are the U.S. and Britain the only countries to still be using the FPS system (foot-pound-second) and not the metric system. I guess the U.S. just likes to be stubborn. Hope this helped.
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Thanks Karen for the info and the link.
Cheers
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Yeah...have a great day
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Historically we have used 240V, and mainland Europe used 220V; but some years ago mainland Europe and UK standardised on 230V with sufficient latitude that 240V and 220V would remain within permissible tolerances.
As the current for 230V is lower (for the same power) as the current required for 110V, so there is less heat generated in the wires (and so less resistive losses in the domestic wiring system).
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Historically we have used 240V, and mainland Europe used 220V; but some years ago mainland Europe and UK standardised on 230V with sufficient latitude that 240V and 220V would remain within permissible tolerances.
As the current for 230V is lower (for the same power) as the current required for 110V, so there is less heat generated in the wires (and so less resistive losses in the domestic wiring system).
...Thanks George..so more volts means less current !...YAYYYYYY !!
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In 3-phase applications (for driving machinery and such things) in continental Europe we also use 380 V and even 500 V. How is that in the UK and US ?
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I have never read up on that. not even in my basic wiring books. I did not know people used that amounts of volts.!so does that mean it is less then your typical 220 and 110 volts??? OH Morning Eric!
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Good morning Karen (it's afternoon over here).
Current practice around here is this : the company supplies 3*380 V, which means 380 V between phases or 220 V between a phase and the zero.
For household applications (including your washing machine and drier) you get one phase and a zero, so you have 220 V. But e.g. your local launderette will receive 3 phases, which means they can branch between two phases and use 380 V or between a phase and the zero where they want to use 220 V.
Semi-industrial or industrial plants will often have 500 V or receive high tension.
Main advantage for the supplier is that it can use lighter wiring and will have less losses between its transformers and the consumer's meter.
I mentioned "around here" because I am aware that it is not yet so everywhere in Europe yet.
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Thats interesting . I have had some wiring education , very little. I have been trying to learn about simple wiring..so I can repair things myself! LOL I can change out plugs light switches install fixtures etc. I want to learn how to do a rewire but I need to learn more about wire gauges ( size etc. I kinda understand about amps on certain outlets and limits about what can be run off individual breakers etc. It is complicated for me.. I would like to take two courses which you end up with a certification in electrical installation repair etc..A licensed Electrician.
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Very Interesting Eric ..Thank you so very much...and Karen..I am very impressed at your wishing to dive in. In fact, you're pretty handy around the house !..you can certainly show me a thing or two abut DIY !
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It only comes with years of practice and lack of funding to hire out! LOL!
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I know this reply is three years late, but as no responses were made regarding 3-phase supplies in the U.K. and the U.S., I thought I'd comment.
Here in Britain, the standard system is a 4-wire wye (also called star) arrangement, which supplies 240V phase to neutral and 415V between phases. It's used to distribute power around most neighborhoods of any size, even when only residential properties requiring only single-phase power are supplied.
The 240V value became the standard by the early 1970's. Prior to that there were minor variations in the declared nominal voltages from area to area, such as 220, 230, or 250V. As noted previously, officially the U.K. now uses a nominal 230V, but that was pure political meddling with the permissible tolerances.
The situation in the United States is rather more complex, as various systems have been employed at different times, and although some arrangements are now considered obsolete, there are still many of them in use.
Wye systems are generally installed as standard these days, with one arrangement being configured to provide 120V phase to neutral for regular portable appliances etc. That results in a corresponding phase-to-phase voltage of 208V. This configuration is sometimes written as 208Y/120V.
Where larger amounts of power are required, a wye system at the higher voltages of 480Y/277V is employed. The reasons for this are as mentioned earlier in the thread - Higher voltages result in lower currents for any given amount of power.
Note that in all these systems the relationship between the two voltages is fixed mathematically due to the 120-degree difference between the three phases. Phase-to-phase voltage is always equal to the phase-to-neutral voltage multiplied by the square-root of 3.
There are also 3-phase delta systems still in use around the U.S. These are normally 240V or 480V (measured phase to phase, as there is no neutral). Again, the higher voltage was provided where power demands were greater. The old 480V delta system is the reason for the later adoption of the 480Y/277V arrangement, since the phase-to-phase voltages are the same.
Since 120V is required in most places in addition to any higher voltages, it's not at all unusual to have multiple systems within a commercial building, e.g. the power company supplies 480Y/277V then there's a separate transformer inside the building to provide 208Y/120V as well.
The old 240V delta system also gave rise to a 4-wire delta arrangement in order to get 120V from the same system at minimum cost. A center tap on one winding is extended as a neutral, so that 120V can be obtained by connecting between one of two phases and neutral.
When it comes to operations requiring vastly greater amounts of power, then in all countries it's common to supply three-phase power at much higher levels of thousands of volts, with transformers on site to step it down where required.
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I think most homes in the US are now supplied from a 240V single phase secondary with its center-tap tied to neutral to provide two "rails" at 120V, 180° apart, or a rail-to-rail voltage of 240V for major appliances, water heaters and the like.
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Yes, a 3-wire single-phase 120/240V service has been the norm for residential supplies in the U.S. for many years. The 120V loads (lighting, general-purpose receptacles etc.) are distributed as evenly as possible across the two sides of the supply. The 240V loads (range, dryer, water heater, larger space heaters & air conditioners etc.) have the benefit of lower current draw at the higher voltage.
A similar arrangement was employed in England in the early days, but it was soon decided to double up the voltage, which is how 240V (or thereabouts) came to be the standard here for all domestic appliances.
Although more developed areas in Britain always employ 3-phase distribution, with regular houses just fed from one phase, in more rural areas we still have 1-phase 3-wire distribution networks which are similar in principle to the standard U.S. residential system, just operating at 240/480V instead of 120/240. Most houses need only a 2-wire 240V connection, so about half the houses are connected to one side of the supply, the other half to the opposite side. Some larger buildings, farms, and so on take a 3-wire supply.