110V to 115V to 117V to 120V to 125V When Did It Happen?

[Speedskater]

110V to 115V to 117V to 120V to 125V When Did It Happen?
Not so much when was it listed in the code book, although that would be interesting.
But when did the typical POCO go to it as their average voltage?

 

[K8MHZ]

110V to 115V to 117V to 120V to 125V When Did It Happen?
Not so much when was it listed in the code book, although that would be interesting.
But when did the typical POCO go to it as their average voltage?

This may help:

Originally, the service voltage was about 90 volts direct current, which was Edison's plan. Tesla proposed that the electrical grid be alternating current (AC) and competed with Edison for the first generating plant to be built in the State of New York at Niagara Falls. Edison proposed a DC system and Tesla an AC system. History tells us that Tesla won the competition, and because of that the industrial revolution was quickly accelerated. Had Edison won we would probably still be in the dark ages because of the inefficiency of transmitting DC current over long distances. While Edison was promoting the electrical light bulb around the country, almost every town required its own generating station because DC would lose so much in the transmission that it became unusable after only a couple of miles.

Tesla also had invented the poly phase alternating current generators that provided for the ability to generate the voltages necessary for long distance transmission. Tesla kept the voltage about the same as what Edison started but raised it to the 110 volts alternating current (VAC) because of the higher related voltages of 220 VAC and 440 VAC, which were integral to the more efficient poly phase generators.

The standard voltage available in most parts of the country (US) is now nominally 120 VAC volts +/- 10%, and can vary from 108 VAC to 132 VAC. It's usually around 117-118 VAC.

http://wiki.answers.com/Q/Why_was_1...of_homes_in_the_US_and_not_some_other_voltage

FWIW, my '120' is about 123 here.

I don't know if there was an exact date when the voltages were changed. Also, the voltages, over time, may have changed meaning. For instance, does the voltage rating mean the voltage from the generator or at the user end? Is it a target voltage, an average voltage or a maximum voltage?

Great question though!

 

[K8MHZ]

Just to add, 125 volts is the maximum rating on a receptacle. That would be a standard receptacle used on a 120 volt system. I have some old ones, like from the 50's or 60's that also have that rating. So, 117 volts may be the device rating meant to be used on a 110-115 volt system.