Lee Schierer
USNA '71
Go Navy!
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Yes, well - the OP asked the question 6 years ago <g>.
In the US the voltage is either 208 or 240 volts, 220 is a pre-war voltage, where 220 still exists it is 50 Hertz & the color code is brown for the hot/live, blue for the neutral, and yellow with a green stripe for the grounding/ earth conductor, it is derived from 220/380V 3 phase wye or "star" as it is referred over there, line to neutral is 220V, line to line is 380V, the European Union "harmonized" the voltages to 400/230V because some countries like the UK, & France, were 415/240V & others were 380/220V so they went in the middle, nothing changed though other then 1 standard across the EU.
If you look at electrically heated appliances like ranges, dryers, water heaters they have 240 volt ratings, if the voltage were still 220, there would be reduced performance when they are operated at a reduced voltage, the elements will operate at a reduced wattage, a note though: ranges & dryers are 120/240V & do require a neutral as they have components that require 120V.