Why do they use 120v in the US but most other countries they use 220v or more?

9 Answers

  • 1 decade ago
    Favourite answer

    other countries doesn't want to spend the money to step down the voltages on their cable plant. overseas 220 volts is actually better cause you have less current draw verses 110 voltage.

  • 1 decade ago

    Before our time, there were no standards set between USA and other countries. US adopted 120V, but third world countries adopted 230 volts.

    I don't think it was current that was the issues. I think it was more or less logistics was the issue. Most third world countries did not have issues of power quality until the last 20 to 30 years. Here in the US, we are used too (+) (-) 10 volts deviation, but over seas they were like old rusty nasty swings in the voltage as if they were all on Back up generators on a cold start. So power quality issues were much more critical over seas, but here in the USA, we are use to great power. It is pretty easy to control 120 volts, but because 230 was more spread out and can handle longer distance from generation locations, they needed higher voltage to get from point A to Point Z. There is significant voltage drop, and as a result the current will rise. The thing about 230 volts is if you have more voltage, you can actually have lower voltage drop which causes more over current that fries PC boards

    Source(s): My advise is to use a AVR or automatic voltage Regulator, to control your voltage drops, and over current issues. I have them, if you need them.
  • 1 decade ago

    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.

  • Anonymous
    1 decade ago

    C Rock has two errors, one of which could kill you:

    The UK hasn't used FPS for decades, we use the SI system for everything except a few domestic measures (pints of beer, miles per hour - cars and trains only).

    The reason that you're flung off if you touch a live wire is because it carries AC, not because it's 230volts. If it's 110V or 230V you will get clamped and fry if you grab a DC line.

    Incidentally, the United Kingdom and the whole of the European Union is standardised on 230v 50Hz single phase and 400v 50Hz three-phase. All other quoted voltages are obsolete. Having said that, heavy loads will reduce the line volts a bit. Frequency is considerably more stable.

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  • Anonymous
    1 decade ago

    C_Rock's answer was superior, so not much to add to it, but just a little extra info...back in the early days of electricity in the US, there was an intense rivalry between Thomas Edison and Nicola Tesla - the preeminent experts in electricity at that time.

    Tesla favoured the 220v standard while Edison favoured 110v and in the end, Edison being more politically powerful, had his way.

  • 1 decade ago

    C_Rock's answer is quite good apart from two things:

    Whether it's 110V or 220V, one doesn't get "glued" to the live wire in case of accident and that, because it's AC, not DC.

    About the FPS system, the americans are getting confused...

    A space probe crashed on Mars because one part of NASA worked in feet and inches and the other in meters... Oups... Still makes me laugh a bit...

  • Alan
    Lv 6
    1 decade ago

    Further to the points already raised, may I point out that many US houses require 2 phases of power.

    Items run on 2 phases get about 230 volts.

    Washing machines in particular require the extra volts in order to drive the motor with enough torque (twisting power).

    I guess that, with so many items running on 120v it would cost too much to change now.

  • 1 decade ago

    It is simply a standard adapted by industrial country(s).

  • Anonymous
    1 decade ago

    Maybe American volts are simply bigger than anywhere else, so you don't need as many.

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