Back when I played on Chesapeake, the powerhour was "on" during the first hour of the shard coming back up from mantinance each day. Then they changed it to 1 hour given to you every 24 hours, and if you went over the 24 hour period by not logging on, the powerhour timer stopped until you logged on, of which it would start you powerhour once you had. Saying the words "powerhour" or "power hour" didn't start your powerhour, what it did was tell you exactly how many hours, min, and seconds until the 24 hour timer was up. If you were already in powerhour when saying it, it would just say "You are in your powerhour" or something to that effect.