LOS ANGELES - Long before there was an Internet or an iPad, before people were social networking and instant messaging, Americans had already gotten wired.
Monday marks the 150th anniversary of the completion of the transcontinental telegraph. From sea to sea, it electronically knitted together a nation that was simultaneously tearing itself apart, North and South, in the Civil War.
Indeed it did. For the first time, a war was conducted almost in real time with direction from the command in Washington. Troops were moved around in response to information from the field, and in conjunction with railroads to move those troops it had great effect on the outcome of many battles, and of the war.
With all due respect, I don't think Edison envisioned a commercial power network, because it could not be achieved with his direct current system. Nikola Tesla laid the groundwork for long distance power transmission by conceiving alternating current, especially polyphase A.C. which became the basis for a national power network, along with many other advantages.
I meant "system", but it was a network in the sense that any commercial company needs to have a combination of people, plan, and ability that makes it into a "network" of commercial interests.
I know that Edison didn't envision a power grid: he once said that the only way to move electricity from city to city was to charge batteries and load them onto railroad flatcars. My point was that he used the same voltage he was familiar with from his days as a telegrapher, and we in the U.S. are still using it, although it has been converted to AC.
The voltage has been bumped a little since Edison. The nominal voltage was raised to 115V in the 30s or thereabouts, and when I was dissecting radios as a youth they were all rated at 117 volts, and these days, everything is rated for 120V.
Edison outright hated AC, to the point where he couldn't see how AC would be a better choice for an electricity system. Edison would have had a world with smallish (DC) power plants on every block.
I suppose Edison gets the last laugh, with the modern systems for transmitting power for very long distances being high voltage DC.
***** Moderator's Note *****
I think it's the Amish who get the last laugh: the economy has made everyone conscious of the cost of leaving lights on and depending on electricity for too many things in too many places.
The idea of getting up with the sun and lighting my house with one or two lanterns seems a lot more sensible to me now.
Yes, that's true, of course, but it's not the point. Edison, who was the prototypical self-promoting hustler, was apoplectic that Tesla's invention was more so much more useful and practical than his. In other words, Edison hated Tesla because Alternating Current threatened, at least in Edison's mind, his status as the "Wizard of Menlo Park" and the public view of him as the preeminent inventor of the time.
Edison was also spiteful about Bell's "Phongraph spelled backwards Gramaphone", which was Edison's competition in the recorded music business, even though Bell's invention was markedly superior in tone quality.
I'm really reaching back (I must have been only 2-3 years old or so), but I seem to remember one of my Grandads telling me that their power [would have had to be Baltimore MD] was DC for awhile and then switched to AC. That would also have been circa early 1900s (the power, not me!).
High-power long-distance DC transmission is now feasible:
The first picture there shows "Long distance HVDC lines carrying hydroelectricity from Canada's Nelson river to this station where it is converted to AC for use in Winnipeg's local grid."
ISTR there were/are a lot of HVDC long-distance lines in Russia; I believe those were described in a 1970s IEEE Spectrum article.
Having a DC local network was common in many places, and could've lasted a long time. An IBM catalog of the 1930s listed equipment in both AC and DC versions.
Somewhere I heard that Philadelphia's City Hall was DC until 1954, don't know if true.
In the early 1900s, it was common for local trolley companies to generate their own electricity to run the streetcars. Many companies had a side business and sold power to the town, and that was probably DC at first.
Streetcars tended to use 600 V DC power and many light rail and subway elevated lines still do to this day (though many use slightly higher voltages, such as 650-750). Some power companies had streetcar systems, too, notably Public Service in New Jersey and New Orleans Public Service.
In the early part of the 1900s, 25 Hz AC was common. Apparently in those years it was a good frequency to use on electric motors of that era (perhaps someone could explain the technical reasons for that.) In the 1910s-1930s, several railroads electrified with that frequency and it's still used to this day on certain Amtrak, SEPTA, and NJT lines.
At some point in the 1930s or shortly later, the commercial power grid became reliable enough to use the 60 Hz as a means to run clocks accurately. This led to the loss of pendulum regulator clocks and Western Union time signals.
In the old days, to convert frequency or convert between AC-DC, giant spinning "rotary converters" were used. These have been replaced with solid state components, though some old units may still be in service in an old substation.
William Middleton's "When the Steam Railroads Electrified" is an excellent resource. Sadly, Mr. Middleton, an expert engineer and author, passed away recently.
I wonder if any fledging local power companies also got into telephone service as well. Both were public utilities and required line poles.
Parts of NYC continued getting DC feeds until about a decade ago. No new customers since 1965 or so, but legacy folk were grandfathered in.
These lines were used for elevator motors (perhaps some other commercial ones, too), as well as some of the lighting equipment on Broadway.
Con Edison strongly encouraged these customers to switch to "regular" AC circuits, using a combination of positive (so to speak) incentives such as chipping in for AC ->DC converters  or subsidizing the cost of new motors. They also kept increasing the basic monthly fee for the DC feeds.
While in most buildings the DC lines were physically separate from the "regular" circuits, only going to the elevator room, there were some buildings where you'd find half the outlets in an apartment carrying standard AC, but half providing DC. I have no idea whatsoever how this passed NYC's building code, as the outlets were all the same standard we've been accustomed to for decades. 
And yes, if you plugged in pretty much anything other than a regular incandescent fixture, you'd run into lots of trouble.
 I helped drag a motor-generator from the top floor up to the rooftop elevator shack in 1980 or so.
 I suspect that another key historical figure involved in electricity was involved, namely Mr. Benjamin Franklin.
- for a mid 1900s reference, check out the following scans from a Lionel Train instruction booklet:
No need to reach back nearly that far. In 1954 when I started college, there were two sorts of dorm rooms -- those with DC electric and those with AC. (There was a reason the electric desk fans of that era bore the markings "AC/DC" :-) .) One of the student agencies rented out inverters and converters for the semester to students who needed them (for running AC equipment in a DC room, or DC equipment in an AC room).
The university power plant had for years been DC only, was at that moment in the throes of a not-yet-completed conversion to AC, and would in fact become AC only (much to the relief of student phonograph-turntable owners) in time for the next academic year.
(Ah, bright college years :-) !) Cheers, -- tlvp
- - Avant de repondre, jeter la poubelle, SVP.
***** Moderator's Note *****
What was Tom Lehrer's famous line?
"Bright college days, oh carefree days that fly To thee we sing with our glasses raised on high! Let's drink a toast, as each of us recalls Ivy-covered professors, in Ivy-covered halls!"
When I was a chiled (teenager or earlier) we travelewd to the West by car and stayed at the Harvey House hotel in Gallup, N.M. As a sat or lay in my room I noticed a stange flicker to the lighting that appeared only if you viewed it from the edge of your eye. If you looked at it straight on it wasn't noticeable.
I finally realized that this must be 25 Hz power, probably from a Santa Fe generator or althernator that supplied their considerable facilities in Gallup.
As far as I know, the Santa Fe at that time had no intention of ever using electric power fro their trains, so they probably used 25 Hz for some kind of advatages that tghe writer mentions. Probably lighting was not a primary concern for their mechanical installations or it was just more or less the efault custom when the power supply was built.
I remember lookding through a shortwave radio listener guide many years ago and for each country it gae the cutomary voltage and frequency and whether the stability of the frequency was good enough to be used for timing.
I don't know the origin of the name but a telephone company serving some of the Los Angeles basin was the Western Light and Telephone Company. There were quite a few independents in the Los Angeles basin at one time that fully participated in the network which was dominated by General Telephone and Pacific Telephone, perhaps in that order.
I remember the first 5XB installed in this primarily step area was by the Sunland-Tujunga Telephonme Company
:> I'm really reaching back (I must have been only 2-3 years old or so), :> but I seem to remember one of my Grandads telling me that their power :> [would have had to be Baltimore MD] was DC for awhile and then switched :> to AC. That would also have been circa early 1900s (the power, not me!).
:Having a DC local network was common in many places, and could've :lasted a long time. An IBM catalog of the 1930s listed equipment in :both AC and DC versions.
Was that 120V DC (or so), or 48 V DC? Telco plant is 48V DC, and it's very common for computing equipment installed in telco faciilites to be so as well, beause it makes power distribution easier. (And, of course, you can run it off the great honkin' battery plant when the commercial power fails.) I woulnd't be surprised that IBM were making equipment for that market, for billing calculations, for instance, but I'm not aware of it.
In the early 80's IBM made a computer system that added electronic options for old Step offices, it was a total mess and they sat in place for years after they were out of service since neither IBM or Bank of America who owned them wanted to pay to remove them. In time we junked them out. They were called System 7.
I don't know the DC voltage for IBM equipment that took it. I would guess it was the standard voltage used by DC installations of the era.
Billing was a major application for IBM's punched card tabulating machines, and the Bell System employed plenty of those machines. Indeed, they used a punched-card as the turnaround-document into the
An IBM history suggests IBM halted its own modem development of the
1950s to avoid upsetting AT&T which was a major customer of IBM equipment.
But the billing departments were not necessarily located in the same building as the switch gear. Often the billing department was located in its own separate office building along with other administrative workers (ie service reps, other accounting, personnel, engineering, legal, etc.)
Parts of Buffalo and Niagara Falls NY had 25 Hz power for a while. The area didn't get 60 Hz power until 1930, and 60 Hz power consumption didn't exceed 25 Hz consumption until 1952. The power company wouldn't sign up any new 25 Hz customers after 1947.
25 Hz power came from Canada after the last US 25 Hz generators were retired (or destroyed in the Schoellkopf collapse?). Some of the 25 Hz customers used it just for elevators, apparently upgrading them to 60 Hz power required bringing the elevators up to current standards. Finally a date was set where the 25 Hz power would be terminated on a certain date in 2007. However, an October Surprise snowstorm in October 2006 destroyed the power lines, and it was deemed not economical to repair them since it was already decided service was to be terminated in about a year. There were just 5 customers left at the time.
-Mike (dealing with our own October Surprise Storm)
Safe Harbor Dam near Lancaster, Pennsylvania, still generates 25 Hz for the southern parts of the Amtrak (ex-PRR) northeast corridor electrification system. Amtrak uses static converters and a few remaining motor-generator sets to supply the rest of the 25 Hz load. (North of New York City, the NEC uses standard 60 Hz power, 12 kV to New Haven and thence 25 kV to Boston.
+--------------- | In the early part of the 1900s, 25 Hz AC was common. Apparently in | those years it was a good frequency to use on electric motors of that | era (perhaps someone could explain the technical reasons for that.) | In the 1910s-1930s, several railroads electrified with that frequency | and it's still used to this day on certain Amtrak, SEPTA, and NJT lines.
This Wikipedia article claims that it was due to Niagara Falls:
... 25 Hz origins The first generators at the Niagara Falls project, built by Westinghouse in 1895, were 25 Hz because the turbine speed had already been set before alternating current power transmission had been definitively selected. Westinghouse would have selected a low frequency of 30 Hz to drive motor loads, but the turbines for the project had already been specified at 250 RPM. ... Because the Niagara project was so influential on electric power systems design, 25 Hz prevailed as the North American standard for low-frequency AC.
And I was going to discuss the use of 400 Hz power in aircraft, but the same article covers that too: ;-}
... 400 Hz Frequencies as high as 400 Hz are used in aircraft, spacecraft, submarines, server rooms for computer power, military equipment, and hand-held machine tools. Such high frequencies cannot be economically transmitted long distances, so 400 Hz power systems are usually confined to a building or vehicle. Transformers and motors for 400 Hz are much smaller and lighter than at 50 or 60 Hz, which is an advantage in aircraft and ships. A United States military standard MIL-STD-704 exists for aircraft use of 400 Hz power.
A lot of the "whine" you hear in the background of the seat-mounted headset audio (or sometimes even in the overhead cabin announcements) is 400 Hz that has leaked into the audio path. [400 Hz is just slightly higher than G above middle C, so it is quite audible even at low levels.]
+--------------------------------------------------------------+ Rob Warnock
627 26th Avenue San Mateo, CA 94403
400 Hz was popular for some mainframe computers. Maybe the thinking was that they ought to have a motor-generator set anyway for isolation from the power line, so might as well make the generator side 400 Hz while they were at it. Burroughs 220 (vacuum tubes), IBM 7030 (Stretch) (Transistors), and IIRC IBM 709x (transistors) among others. The reasons were the usual, smaller transformers and easier to filter out the ripple. The ripple frequency was 2400 Hz, since they used three phase power.
I think there is another 25 Hz hydroelectric plant in Maryland that also feeds the Amtrak & nearby 25 Hz system.
The oldest hydroelectric plant still in use in the US is in Mechanicville NY. It still generates power at 40 Hz, but the power is converted on-site to feed the grid at 60 Hz. Power from the plant initially fed the GE plant in Schenectady, and was also used for one of the first attempts at high voltage DC power transmission, in 1932.
GE used 40 Hz elsewhere. I've seen a circa-1900 generator in a mill building in Massachusetts. I forget the power rating but I do remember the label stating it generated power at 40 cps at 550 volts.