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

[Jeff Geerling]

I run into 60Hz derived timing gear a lot in old buildings. Parking lot lights, exterior signage, especially. I was just upgrading the network at a place built in the 60s that still has one of those timers. I think it was made by Intermatic.

-Jeff

> On Jul 16, 2026, at 9:10 AM, Bob kb8tq via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Hi
> 
> There are still a multitude of mechanical “plug in the wall” timers out there that do 24 hour 
> or longer device control stuff. Most of it is pretty mundane gear. Most of the timing isn’t all that
> precise. Still, they are out there.
> 
> Bob
> 
>> On Jul 15, 2026, at 6:06 PM, Jim Lux via time-nuts <time-nuts at lists.febo.com> wrote:
>> 
>> 
>> 	
>> 
>> 
>> 
>> I would think that ovens, appliances, and the like don't count cycles any more.  They all have microcontrollers in them, and they'd count oscillator cycles. 
>> Even my 20 year old bedside clock doesn't use line frequency (because it has battery backup, it can't).
>> 
>> Yes, my grandmother's old stove with the clock built in, manufactured some time pre-1960, certainly is line frequency dependent. 
>> A washing machine with a mechanical timer perhaps.  But the old microwave oven I have in the garage that has a "turn knob to set cooking time" uses a *mechanical* spring wound timer. 
>> 
>> Is there anything that uses line frequency as a time standard any more (other than weird stuff like PDP-11's using line frequency for RTC input)
>> 
>> Older timeclocks controlling lighting (the ones with the pegs to turn and off) probably use synchronous motors. Same with the household timers that one might use for holiday lights.  
>> 
>> I note that in a new installation for lighting controls, almost invariably, for exterior and sign lighting they're required to be "astronomical" timers that know when sunrise and sunset are. (CA TItle 24, ASHRAE 90.1) (or photodetectors). And for interiors, they're required to be able to automatically deal with holidays and daylight saving time. That pretty much means the old mechanical timers have limited uses.
>> 
>> 
>> 
>> 
>> On Wed, 15 Jul 2026 15:15:10 +0000, "Thomas D. Erb via time-nuts" <time-nuts at lists.febo.com> wrote:
>> 
>> 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.
>> 
>> Historically, synchronous clocks-and some electronic appliance clocks that count the 60 Hz AC waveform-benefited from long-term grid-frequency correction. Although the instantaneous frequency varied slightly, accumulated error was corrected so that these clocks remained reasonably accurate over time.
>> 
>> Does anyone here know the current status of Time Error Correction on the different North American interconnections?
>> 
>> More specifically, are traditional synchronous clocks now likely to accumulate noticeable long-term error? And what about microwave ovens, ranges and other digital clocks that may use AC zero crossings rather than a crystal or real-time clock for their time base?
>> 
>> I initially saw a reference to an April 14, 2026 NERC/FERC action, but on looking more closely, that appears to concern retirement of BAL-002-WECC-3, a contingency-reserve standard-not BAL-004 time-error correction. NERC still lists BAL-004-WECC-4, Automatic Time Error Correction, as active in the Western Interconnection.
>> 
>> I would be interested to hear from anyone familiar with current utility frequency-control practices, particularly in the Eastern Interconnection.
>> 
>> 
>> Thomas D. Erb
>> o: 508-359-9684
>> p: 508-359-4396 x 1700
>> f: 508-359-4482
>> a: 97 West Street, Medfield, MA 02052 USA
>> e: tde at electrictime.com
>> w: www.electrictime.com
>> Tower & Street Clocks Since 1928
>> 
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