I was in the process of replacing a 23-year old fluorescent tubelight fixture in my garage with a similar (physical) size LED fixture. When I opened up the light, I found that from the ceiling box there were three wires (none of which was a ground wire) coming out. Picture shown below.
Two of these (left and middle) were combined with a wire from the fixture using a twist connector. And another one from the box (right) was connected to another wire from the fixture.
When I turned the mains back, I find that the wires on the two extremes were both hot wires and the one in the middle is a neutral. And, both these hot wires are both hot even when the switch (the one that operated the fluorescent lamp) is turned off.
About a foot away on the ceiling is the plug to my garage door opener. When I removed the light fixture, the garage door opener stopped working and in fact that plug does not have power.
I did a quick test -- connected the hot (right) and neutral (middle) to the new LED fixture and it works perfectly. The hot on the left was just capped. The garage door plug did not get power.
QUESTION -- should I connect it back the way it was (description above) and are these connections making sense? Why is a neutral and a live being connected here?