I need some help figuring out the wiring in my switched ceiling junction box in order to connect a basic light fixture. In the box I have three pairs of black/white wires and one yellow wire. My fixture has one pair of black and white wires.
Initially, all the white wires were connected and all the black wires were connected. My three-bulb light fixture has a pair of clear wires: one smooth and one ribbed. Treating smooth as black and ribbed as white, I have followed the procedure basically outlined here
, ignoring the yellow wire. I was able to identify the pair carrying power, but I haven't been able to identify which pair goes to the switch.
Let's say my the wire pairs in the box are A, B, and C. When I connect up my fixture to A only, all the light bulbs turn on, so A is my power source. One of the other pairs should go to the switch, and the other should go to the next fixture in series (wall outlets in this case). Following the procedure linked above, testing whether B leads to the switch yields no circuit whether the switch is on or off. Testing whether C leads to the circuit causes only one of three bulbs in the fixture to flicker whether the switch is on or off — the other two bulbs stay off. (The bulbs are CFLs, but this is concerning.)
I have studied electronics and feel like this should be a simple problem to solve. I have diagrammed the possible connections several times. I have experience installing about a dozen ceiling lights in the past with no issues, including some that required diagramming and testing like this. I am using proper safety precautions and switching off the breaker while working at the junction box. I don't believe polarity should be an issue with the CFLs since they are AC two-terminal devices, and diagramming the connections shows that the polarity shouldn't change from when I isolate live-pair A and get the fixture to light up. The wiring in the ceiling was installed in the last year as part of a significant apartment building renovation, so presumably they it is all properly installed.
Difficulty level: I don't have access to a voltmeter or even a simple line tester right now.
What am I getting wrong? Is the single yellow wire important?