Mike Berger wrote:
In the U.S. the power grid is very accurate over long periods of
time. But what are the odds of running six months without a single
power interruption?



Depends where you are, I used to have outages a couple times a year, now
the house I'm in I've had exactly one outage in almost 2 years and it
was a pretty good storm that went through.

Aside from that though in both the US and UK the mains frequency has
excellent long term stability. It may gain or lose a few seconds over
the course of the day but it will be dead on over weeks/months.