I was told by our school electrician that long ago the clocks were adjusted by the power company. So around 2am DST they would either send power at 59Hz* to fall back or 61Hz* to spring forward. This was from the era when power grids were separate and analog. With newer national grid-tie it might not even be possible to do now.
replyI don’t know about that, but I was told by someone who worked at a power generation plant in the 1970s that they had a clock in the plant, that they would compare to the time broadcast on the radio frequency that carried the official time, and any time it diverged they would slightly adjust the frequency of the alternating current until it matched.
replyI was a kid but I do know the clocks in my elementary, middle, and high school were accurate. Near end of day, we would impatiently stare at the clock waiting for the release bell. Being a public school, the clocks were bolted securely to the wall. Being little shits, students would probably steal them if they could, LOL. So how did they keep 100s of clocks on time? I asked and was told by the school maintenance that it was done through power.
replyIt's crazy they didn't have a centralized clock system in a facility like that. What a thing to scrimp on.
replyI'd laugh whenever I looked up and saw the wrong time....
replyI worked in a Network Operations Center in the early 1990s, and there was a large projection display with four other monitors around it. Across the top were four round analog clocks, representing the time zones of the United States. I was one of four operators, all in our 20s.
replySo, Daylight Savings Time ended, and the early-morning operator had all the clocks set by the time I arrived, and the third operator came in, looked at them, and said "Great! So, did you take all four of them down and adjust the time individually?" "Yeah" "Didn't think about taking one off the end, adjusting it, and moving the others down the row?" *facepalm*