Had a fun one at work today. Clocked in at 5am. Half way down the factory I had around 80 parts hanging from the day before, all motionless except for one rack of around 14 parts which where swinging like mad. Nothing else was moving except for these few parts and they where all hanging together. It was a bit eerie and not the first time something like this has happened.
Must add, no obvious signs of a draught, no one else had been in. They carried on swinging for around an hour and 45minutes... Slowig down then speeding up again. I did take a little video which I will try to add.