After I installed a set of wires, the spark effect you get when pulling the wires remained suspended in air. I removed all the wires and electrical components from scene, the sparks are still floating in the same location. I tried selecting the object in console to disable it, but apparently it's an unselectable object. Initially I thought it's gonna go away after a game restart so I kept playing for hours. Today I loaded the game and the sparks are still there. Here is a youtube video I found with an identical problem /watch?v=VKIsej-popk

I've got this problem too. It doesn't appear to be going away.