An engineer then predicted that it would take 45 years

Tuesday, June 14th, 2022

Fifteen years ago, Con Edison finally ended its 125 years of direct current electricity service that began when Thomas Edison opened his Pearl Street power station on Sept. 4, 1882, the New York Times reported

Con Ed will now only provide alternating current, in a final, vestigial triumph by Nikola Tesla and George Westinghouse, Mr. Edison’s rivals who were the main proponents of alternating current in the AC/DC debates of the turn of the 20th century.

The last snip of Con Ed’s direct current system will take place at 10 East 40th Street, near the Mid-Manhattan Library. That building, like the thousands of other direct current users that have been transitioned over the last several years, now has a converter installed on the premises that can take alternating electricity from the Con Ed power grid and adapt it on premises. Until now, Con Edison had been converting alternating to direct current for the customers who needed it — old buildings on the Upper East Side and Upper West Side that used direct current for their elevators for example. The subway, which has its own converters, also provides direct current through its third rail, in large part because direct current electricity was the dominant system in New York City when the subway first developed out of the early trolley cars.

Despite the clear advantage of alternating current — it can be transmitted long distances far more economically than direct current — direct current has taken decades to phase out of Manhattan because the early backbone of New York’s electricity grid was built by Mr. Edison’s company, which had a running head start in the first decade before Mr. Tesla and Mr. Westinghouse demonstrated the potential of alternating current with the Niagara Falls power project. (Among the customers of Thomas Edison’s Pearl Street power plant on that first day was The New York Times, which observed that to turn on its lights in the building, “no matches were needed.”)

But direct current clearly became uneconomical, as the short distances that it could be transmitted would have required a power station every mile or less, according to Joe Cunningham, an engineering historian. Thus alternating current in New York began in the outskirts — Queens, Bronx, Upper Manhattan and the suburbs.

The direct current conversion in Lower Manhattan started in 1928, and an engineer then predicted that it would take 45 years, according to Mr. Cunningham. “An optimistic prediction since we still have it now,” he said.


  1. Redan says:

    There’s a historical drama ‘The Current War’ about the struggle between Edison (DC) and Westinghouse/Tesla (AC) that is OK.,war%20of%20the%20currents%22).

  2. Gavin Longmuir says:

    “The direct current conversion in Lower Manhattan started in 1928, and an engineer then predicted that it would take 45 years …”

    The fact that DC current continued to be supplied for 94 years indicates how well made was the old DC electrical equipment which just kept on running & running — and none of it imported from China.

    Ever get the feeling that we used to be able to do things a whole lot better?

  3. Bob Sykes says:

    If the British scientists are right about the correlation of IQ and reaction times, then 125 years would entail a reduction in mean IQ of 12.5 points, almost one standard deviation.

    So, yes, once we could do things better.

  4. Goober says:


    Yeah, I do. But at the same time, we do so many things better now than we ever did back then.

    I think that some of what is going on is the fact that we didn’t exactly know what we needed to do to meet requirements for longevity and such back then, since we were in the infancy of the technology, and so the answer to that was to overbuild everything.

    I don’t know this for sure, granted, this is just speculation on my part, but in a lot of these cases of old tech lasting forever, the reason is because it was simply overengineered to a point that would be considered ridiculous today, because they didn’t know the limits back then.

    If we overengineered everything in this day and age, it would be cost-prohibitive, so we try to hit a balance between “this will last until the sun goes Red Giant” and “we can actually afford to build this”.

    I’m not saying we’re doing a GOOD JOB of that, I’m jsut saying that I think that’s the explanation.

    Some things last a lot longer today, too, let’s not forget that a Ford Model A making 35 horsepower from this era would be considered an anomaly if it made 50,000 miles because metallurgy just couldn’t allow white metal bearings to last very long. Now we have 300 horsepower engines lasting 350,000 miles all the time.

  5. Goober says:

    Bob Sykes,

    You said it yourself: IF. The longest word in the English language.

    Yes, there was a study about reaction time that lead to a statistically significant conclusion that IQ had dropped. However, there are other studies using different metrics indicating that IQ is rising.

    Evolutionarily speaking, the “IQ is dropping” hypothesis seems dubious, as well. While I would accept that there are likely less evolutionary drivers towards intelligence now than there were, say, a couple of generations ago, and that could possibly make it perhaps possible that human IQ may begin to drop, there hasn’t been nearly enough generation for such a forcing to start having any effect. As well, better nutrition, better education, etc all would be indicators for higher IQ, population wide.

    As far as I’m aware, that one study is the only one so far that has indicated a net decrease in IQ. All others indicate increasing IQs or stable IQs. And that one study relied on what I would consider to be a pretty dubious metric, which is reaction time, without, to the best of my knowledge, accounting for a myriad of confounding factors.

    Maybe the correlation between IQ and reaction time isn’t very strong (as you rightly questioned, yourself). Perhaps 100 years ago, people lived lives that required them to have better reaction times, and so they were more practiced. If you just consider the fact that 100 years ago, almost everyone was around large animals quite often, even in the city, that, alone, would indicate one huge confounding factor – a person that has lived his entire life dodging the whims of 1000 pound, easy to startle equines on the city streets would probably have a pretty decent reaction time, even if he were a dullard.

  6. David Foster says:

    I don’t think it’s necessarily true that because the DC service continued to be provided, then the original DC conversion equipment continued to be used. Some of it may have been replaced with other rotary converters, some of it with solid-state converters. Maintaining the service for as long as they did was a business and probably also a political decision.

  7. Jim says:

    This is why Shakespeare recommended to kill all the lawyers.

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