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I have seen old appliances rated at 100 Volts and 105 volts. 110 volts became standard. Companion voltages were 220 Volts and 440 Volts
I remember reading (and I have been looking for the reference for decades now) that a decision was taken to increase the voltage to 150 Volts. This was to be done at the rate of 1/2 Volt per year. That was a good choice considering the expected life of distribution transformers of the day. This may have started in the 40's probably after the war.
20 Years on, newer insulations greatly increased the expected life of distribution transformers and 120 Volts was performing well.
That was the reason that appliances were rated at 112 Volts for 5 years, then 115 volts for 5 years and finally 117 Volts for 5 years.
Industrial voltages went from 440 Volts to 480 Volts, but I don't know the timetable. In some areas of Canada the industrial voltage is now 600 Volts.

Bill
--------------------
"Why not the best?"
Jimmy Carter

Great discussion. Very interesting topic, I am interested in this too. In my town and industry we had a little different scenario. Early in the 1900's about 1902 or 03 their was a hydro power station built on a river here. There was no central electricity grid in this section of Maine at the time. Our hydro station was operated at 40Hz about 9000 volts. The town and mill here were supplied and flourished. I am going to guess but about 1927 we were connected to the U. S. power grid that was being operated at 60hz. Some one nationally had changed their mind and chose 60hz over 40hz. Transformers and inverter were used to convert the power down to 40hz for use in the area, eventually the town and some of the mill was changed over to 60hz 440 volt. But even as recent as the 1980's we still had a 40hz system operating at 450volts in the older part of our mill. I try to get as much info on this as I can just for my own curiosity. It is all changed over to modern systems now and mostly forgotten about.
Another interesting thing that I have noticed is that when I buy incadescent lightbulbs they are 115 volt rated. With the power coming into my home is sometime about 120- 121 volts from the local transformer, these bulbs burn out often. But once and a while at discount stores we get a shipment of lightbulb from Canada and they are 125 volt rated and last longer. That's enough of my rant, interesting stuff.
Doug

As I recall it, the original 110VAC came about because of Edison using 110VDC generators (dynamos) for lighting. Despite Edison being famous for bringing electric lighting to reality, he did not invent electrical generation, he simply found a new way to use it. So the first dynamo he used to demonstrate his lighting was one built by Werner von Siemens for use in electric railways. He used 110VDC because he had relatively large motors to run with it. Edison didnt so much pick a voltage, he settled on one based on what he could get at the time. Once that proved to work, he made his bulbs based on that. Since the bulbs don't care if it's AC or DC, Westinghouse and Tesla settled on delivering 110VAC to homes because then the would be able to use Edison's lamps.

I don't think it really "inch up" on purpose, what i recall reading somewhere was that there originally were NO standards. Early electricity providers, also being forced to be appliance mfrs in the early days as well, each created their own voltage level standards, most likely to aid in the perception of the as yet ignorant public that they had to stick with one source.

I believe it was the REA in the 30s that finally established standards and compromises. I've read a history of the REA, that's where I believe I got these concepts. I've also read a history of ANSI, but it was not specified to voltage levels, just saying which previous standards organizations went into creating ANSI standards, which are what we use now, but from that I think you can research the electrical predecessors for those standards and the REA program is in there.

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There was a point in the 1920's where some companies used 6.9 kV as a distribution voltage. We have three such units from that time, but all are 60 Hz. In other utilities in the area they did use 40 Hz, and a converter for 60 Hz. We also have photos of some of our early plants where the units were belt driven from the Prime Mover's (no photo's of the PM's).

I also noticed the early street cars used 600 V DC, and this was because of the DC motors. But many different cities used very different voltages for there street cars (mostly DC).

The history is very interesting because it gave us places names like Battery Park (guessing it came from the old Edison plant).

I think that Battery Park is named for the battery of guns once there to ward off naval attack.

Thanks for correcting me. That wasen't tought in history class (I'm also not from the East coast).

Without giving details, there once was a lake that was made to cool a powerplant. The plant is no longer there, but the lake remains. I am sure there are other monuments to the power industry.

You can't discuss distribution voltages without discussiong two phase electricity, and the Scott-T transformer to convert three phase to two phase.

From the Wiki article on the REA:

Quote:

REA crews travelled through the American countryside, bringing teams of electricians along with them. The electricians added wiring to houses and barns to utilize the newly available power provided by the line crews. A standard REA installation in a house consisted of:

A 60 amp, 230 volt fuse panel, with:
1.A 60 amp range circuit
2.A 20 amp kitchen circuit
3.Two or three 15 amp lighting circuits

A ceiling-mounted light fixture was installed in each room, usually controlled by a single switch mounted near a door. At most, one outlet was installed per room, since plug-connected appliances were expensive and uncommon. Wiring was performed using type NM nonmetallic sheathed cable, insulated with asbestos-reinforced rubber covered with jute and tar.

So it appears that because of the fact that the crews were sent out with identical packages to be installed in rural farms, they settled on 230V (and thereby 115V) as the standard. The REA took the rural farm users from less than 11% electrified in 1934, to over 50% by 1942 and almost 100% by 1952; that was a LOT of systems installed in a short period of time. I read one article that said they electrified over 228,000 farms in 1939 alone. The ANSI standard is now 115/230V, so I'm sure the weight of the REA efforts over a very broad area drove the market to adopt this.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
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Just a clarification. The ANSI standard for voltage is 120/240 not 115/230 V. This applies to the service point. The motor rating associated with 120 V systems is 115 V, and the 230 V motor is used on the 240 V supply.

I'm with magoo2. The distribution voltage is rated higher than the utilization voltage. The purpose, according to my understanding, is to allow for the voltage drop between the distribution gear and the utilization devices. The definition of distribution gear includes generators, transformers, and switchgear. The utilization devices are loads such as motors. Some confusion obviously arises because of the difference between the distribution voltage and the utilization voltage.

So, with "d" meaning distribution and "u" meaning utilization, the "modern" voltages are:

480V-d => 460V-u
240V-d => 230V-u
120V-d => 115V-u
d/u = 1.043

For the "older" equipment, say from the 1970's (or maybe 1960's, I'm not sure where the line was drawn) back to the 1940's, the voltages were rated differently. I do not have any direct experience with equipment older than 1939 so I cannot comment on that (for the record, I saw "1939" last month). The "older" voltages are:

460V-d => 440V-u
230V-d => 220V-u
115V-d => 110V-u
d/u = 1.045

For medium voltages:

2400V-d => 2300V-u d/u = 1.043
4160V-d => 4000V-u d/u = 1.040
6900V-d => 6600V-u d/u = 1.045

I do not claim the above information to be all inclusive. My experience is with motors in the US at 60hz.

May be story: but I read sometime back.

Edison originally planned everything for 100 V DC -generators,light bulbs.Then after putting up his first line in Manhattan, he found the customers at the fag end of line complaining of poor illumination, obviously due to voltage drop.As bulbs were already made, he could not derate them for 90 V.The easiest thing he could do was to increase the generator voltage to 110V increasing the field excitation. Thus 110 V became standard,leading to 220V ,440V etc and later to 11,22,66,110,220 kV.

First AC power generation at Niagra was 2 phase as Tesla thought that be the simple solution.During stage one,power reached up to Buffalo.But when lines are to be extended to Newyork,developments in Europe caused a huge increase in copper prices and the directors of power company found that line cost will not justify extension to Newyork.Then Tesla mathematically found that three phase lines take the minimum copper for a certain amount of power to be transmitted.As pushed to wall and fearing loss of job, chief engineer of the project Mr Scott invented the brilliant idea of converting two phase to three phase by transformer connections.

History and folklore aside, as magoo says, these voltage levels are covered by ANSI standards. They have not been "creeping up". The standards have an allowable range of voltage and the average voltage in particular locations may be increasing or decreasing, but the standards have not changed in at least 40 years.

I found an old paper that may add some clarification to the history of voltages used at the low voltage level.

• http://files.engineering.com/getfile.aspx?folder=6f6e5444-1fef-4ab1-9659-cb

Thanks magoo2. That information will become part of my personal data base.
Not all manufacturers or suppliers followed the standards in the early days. As part of the inching up process, I have seen household appliances rated at 110V, 112V, 115V, 117V and finally 120 Volts. That was long ago!!

Bill
--------------------
"Why not the best?"
Jimmy Carter

Evolution of voltage rating and frquency in US is well documented. The first meeting of AIEE for standardisation took place on January 26,1898 simultaneously in New York and Chicago. Discussion summary published in Institute Transactions VolXV pages3-32.Report of the subcommittee on standardisation of Generators,motors and Transformers was accepted by AIEE on June 26, 1899 and the first standardisation rules were published in Transactions VolXVI pages255-268.The committtee included such veterans as Steinmetz and Elihu Thomson.Rules were revised in 1902 and published in Transactions XIX pages 1075-1092.Second revision after considerable deliberations from 1905 to 1911, was accepted by The Board of Directors of AIEE on June27,1911.As per this standard, AC low voltage ratings were 110,220,,440 and 550 V.

Next major Voltage standardisation effort was in 1927 at AIEE winter meeting on Feb7-11 at New York. See "Voltage standardisation of A C systems from view point of the Electrical Manufacturer" by F C Hanker(Westighouse) and HR Summerhayes(GE) AIEE pages 161-172.There were three more papers on the subject at the meeting from Utilities and consulting engineers.These papers briefly covered the historical evolution of voltage ratings.

AEP engineers Philip Sporn and H P ST. Clair published "A proposal for International Standardisation of EHv Transmission voltages" in AIEE June,1960.Pages281-284.This paper also covers the historical development of voltgae ratings in US

The current situation is covered by ANSI standard C84.1-2011 " Voltage Ratings (60 Hertz) for Electric Power Systems and Equipment"

Development of frequency rating in US is covered by "Frequency" -D B Rushmore AIEE 1912, pages 955-972 and "The Technical Story of the frequencies" B G Lamme AIEE 1018,Pages 65-89.