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

[Thomas D. Erb]

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
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