Sparks Fly!

I enjoy doing a little electrical work here or there.  I am usually pretty good about cutting power and making sure things are not live while I am working on them.  Such was the case today when I was changing out some light fixtures at work.  There was a light fixture that has never worked since we've been in the place and I had surrounding bulbs go out on other fixtures and decided we needed to replace the one.  Everything was going well except that this particular light was apparently an emergency light and got power from an additional source.  I really don't know how it all works, all I know is that when I cut power I tested power and there was nothing going through my main lines so I cut them loose.  All was good until I was pulling down the fixture and a tight squeeze against the other fixture stripped a red wire that I didn't see and sent some sparks flying.  I did not do a dramatic back flip off the ladder or anything too jumpy but those sparks flying at you will wake you up quick.  No shock took place and it was all pretty quick.  I'll know what to look for next time when it comes to an emergency light.  I ended up with a few challenges and had to replace another fixture but all is up and operational.  It is quite bright now in the back half of the kitchen.