[time-nuts] Re: Has Line-Frequency Timekeeping Become Less Reliable in the U.S.?

[Demetrios Matsakis]

I don’t think the TEC corrections were turned off, in the end.   There was one more stage of decision-making.  Jonathan Hardis and I separately wrote unofficial last-ditch letters as members of the general public.  The Commission decided to go with us instead of the utilities.  It wouldn’t surprise me if the  utilities try to do it again, or if they just ignore the regulations to find out what happens.

> On Jul 16, 2026, at 21:40, Hal Murray via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> 
> Thomas D. Erb said:
>> I recently came across information suggesting that the way the North
>> American power grid handles accumulated time error may be changing, and I
>> had not realized this was even being discussed.
> 
> Old news.  That happened years ago.
> 
> I poked around a bit, but I haven't found a good description of when and 
> why timekeeping on the US power grid was turned off.  It seems like the 
> sort of event that somebody would document with a good story.
> 
> Here is a 2017 paper that talks about it being in the works, so less than 
> 10 years ago.
> 
> Time and frequency from electrical power lines
> https://www.nist.gov/publications/time-and-frequency-electrical-power-lines
> 
> TEC is Time Error Correction.  From the abstract:
> The Blackout of 2003 spawned a new regulatory structure for the electric 
> power industry to improve reliability, and as an unanticipated side 
> effect, a decision process that would most likely eliminate TECs was set 
> in motion. The specific proposal is to retire regulatory standards 
> designated BAL-004 and WEQ-006. We review the relevant structure and 
> governing bodies of the U.S. power grids, and report on the current 
> procedural status of these standards. In addition, we review possible 
> scenarios for the future of the power system as an elapsed-time reference 
> absent TEC. For this, we include analysis of the electric power at USNO, 
> as measured over five years. The TECs appear in the data; an analysis with 
> the industry-supplied record of the TECs indicates that without them a 
> time deviation of about 7 1/2 minutes would have occurred on the Eastern 
> Interconnection (grid) between the daylight saving time switches of March 
> 2016 and November 2016.
> 
> --------
> 
>> More specifically, are traditional synchronous clocks now likely to
>> accumulate noticeable long-term error?
> 
> That depends on what you mean by "noticeable"?
> 
> I think it depends on how reliable your power is.  If the power goes out 
> for a few minutes every month or two (and has to be reset by hand) then 
> you probably won't notice the clock drifting.  If your power is stable for 
> a year, you are likely to notice occasionally.
> 
> 
> Here are some graphs:
>  http://www.glypnod.com/TimeNuts/60Hz/TimeFromPowerLine.html
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
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