What are the differences in voltage between the U.S. and Europe?

Those who travel may run into the problem of not only needing adapters for their electrical plugs but also needing to be extra cautious of what their appliances take in regard to voltage. North America and a few others such as Japan are some of the few countries that use a different quantity of voltage than the rest of the world. North America runs on 100-127 volts/60 Hertz whereas most of the rest of the world runs their electrical systems at 220-240 volts/50 Hertz. Many voltage systems in Europe and the United States run off what is called an alternating current frequency. The following are all of the relevant definitions regarding this concept:

  • A cycle is one complete wave of alternating current
  • The frequency is the number of cycles that a voltage waveform completes per second
  • The unit Hertz is equal to one cycle per second

As an example, these definitions mean that if a piece of equipment or appliance is run at 240V AV 50 Hz then the wave corresponding with the voltage repeats itself fifty times per second while moving between positive and negative 240 volts. At one point Thomas Edison’s standard 110V via a direct current system was primarily used rather than Tesla’s alternating current system that came a short time after. Once the swap was made to an AC system, that was when the divide between 120V vs. 240V occurred. One of the main reasons why the majority of Europe switched over to 240V/50Hz was because it was more efficient. However, it was determined that the citizens of the U.S weren’t able to afford the swap as many Americans already had appliances that barred the use of higher voltages. The higher voltage also posed more of a risk back then, but that isn’t much of a problem now with all the strict electrical safety regulations. The solution to America’s efficiency problem was to supply all buildings with 240 volts but then split it into two 120V circuits. This allowed for appliances that required more power to use it, and those that needed less could forgo the higher amount of voltage. Lastly, this voltage difference between countries involves the need for plug adaptors. In the U.S the type A plug is one with two flat parallel pins and type B plugs have both those pins plus a cylindrical grounding pin. The plug types go from type A to type O for a total of 15 different kinds of plugs used worldwide depending on the voltage needed for the appliance to function.


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