Light fixture with 3 white, 3 black, 1 red wire

Question

I'm trying to replace an old fixture for cosmetic reasons. Unfortunately I've pulled apart the wiring to the old fixture and don't remember how it all connected. The wiring in the ceiling has the above setup. The fixture itself has the standard 1 white, 1 black, and 1 ground wire. I followed this advice...now the light operates from a different switch from before.

I don't understand the underlying wiring so I'm baffled by what's going on.

Edit: here's a photo of the box:

The marked black wire is hot - it lights up my tester when I connect it to any other wire when the breaker is on and the switch is off.

Answer 1

Well, the good news is each cable is unique.

• The /3 cable is not like the other cables, and there must be a reason for the extra hot. Was this ever a fan/light? It may also be a new style switch loop.
• The black wire with the white tape is weird (usually it,s the other way 'round) but that tells us that the black, and its partner white, are special. They may be a switch loop, and I would check for that with an ohmmeter after confirming power off.
• The other /2 cable is plain. I have a hunch it's either supply power, or onward power to another location.

Now, the question is what else is around here? Is there another light? What's in the switch box? Etc.

Also, what else has lost power?

Answer 2

It's most likely a 3 way switch application. So two switches should operate the fixture. There are a few different correct ways to connect 3 way switches. There are many wrong ways to connect them. Based on the information above, you most likely need to connect fixture black to box red, fixture white to box white and ground to ground. Two switches should operate it. Example top of the stairs - and bottom of the stairs. It's not always the case but the red wire indicates a 3 way application and multiple blacks tied in together suggests that they are the power supply to the switches. Google 3 way switches.