Chain on the shutter could catch on the light bulb cage.

A chain allows two levers to pull the lower section of the shutter up or leave it down. This section is a part of a two piece rolling shutter on the dome. The chain could catch on the light bulb cages that are high up on the walls.

So the chain caught on a light and popped a zip tie that kept part of the chain in a long string. To make things worse, I was tired and later showing some visitors the sky and had the lower section down. This allowed the chain which was then in a loop to catch on a light bulb, without my noticing it. As the dome rotated, it started to tear the light off the wall. We caught it in time before it completely tore the light off, but the light is partially out of position. To prevent future problems, I went to a local ACO storre and bought a short piece of hose. I pulled the chain through a piece of the hose and attached a hook on the end of the chain the will keep the chain inside the hose. Now the hose will harmlessly slide over lights in the future and it's a little nicer to handle as it provides a good grip and doesn't have any rust or dust which the chain had on it.

Chain with vinyl hose on it shown below.