Hi!

This is a ~1 mm hole in the glass near one of the filaments.
Something got hot enough for the glass to melt, and after
that, as they say, the rest was history.

Comments welcome.

I've seen the effect on some very narrow GE tubes in use with conventional
overhead fixtures. When the tubes die, they oftentimes crack a ring in the
glass or blow a slightly larger hole in it at either edge. This makes
changing them "fun".

I'm not sure if it is specific to the tubes or not. The GE tubes have not
proven long lived. I started dating them after some tubes from a different
maker with the wrong color temperature were purchased and installed during
late 2005. All of the misordered tubes are still going strong, nine hours a
day in most locations. The oldest GE tubes date from 2007, and there are
very few left. All fixtures are identical.

William