An interesting light fixture failure

We had an interesting failure in one of the closet light fixtures. We flipped the light switch, heard a loud pop, and the bedroom went dark and the emergency flashlight came on because the breaker tripped. When we looked at the light (because who looks at the light fixture every time they turn the light on?), it was just dangling from the ceiling.

When I got up there to investigate, it seemed pretty clear why the light was dangling. When I got the light fixture down, these two blue pieces fell down.

These had broken off the plastic electrical box for the lighting fixture wiring. It’s where the bracket for the light fixture screws in to. You can see where the pieces broke off in the areas circled in red.

The electrical box looks cracked and broken in a few other places along the top and sides as well. It’s looking pretty bad.

I also found a tiny piece of melted metal and a little bit of exposed wire poking out of one of the wire nuts. So it looks like what happened was when the plastic broke, the light fixture fell, and the small strands of wire poking out of the wire nut and the ground wire were touching the bracket that held everything up. When we flipped the switch, there was loud pop from the short circuit, and the breaker tripped. Fortunately nothing smoked or caught fire.

After seeing the condition of this box, now I kind of want to look at all the other electrical fixture boxes in the house to see how they look.