shovelhandle I also had a light stay on for 24 hrs at about day 21 and luckily I noticed no ill effects. I read a story recently about a guy who discovered his timer was broken and was turning the lights on and off randomly for varying amounts of time. He had no idea how long it had been that way. He noticed that the small flowers had stopped developing and indications that male flowers were forming. He ended up tossing the entire crop as he could not get them to resume normal flowering. All because of a dumb cheapo timer. I guess the lesson is we shouldn't scrimp on quality when it comes to timers. I routinely check my flower room during dark cycle to make sure nothing's on. I admit to having a fair amount of anxiety about it.