I just bought a house built in 1977. I am updating outlets and switches in the house and ran across a fun challenge last night. My father-in-law finished one room and when we turned the breaker back on the lights in the room wouldn’t turn off. I believe the issue is in the outlet box below the switch. It has three sets of black and white wires. I found the set from the box and placed those in the top two positions (1 and 2) on the outlet (black/brass, white/silver) and I have power to that outlet only. When I hook up set B to the bottom two positions (3 and 4), everything turns on (switches and plugs) and the light switch won’t turn off the lights. Set C seems to have no affect on anything. I connected the switch and continuing circuit wires to posts 3 & 4 and opened up the 2nd outlet in the series. It also had three sets of wires?! When I wired it up as shown, everything works the way it is supposed to. However the black switch wire can’t touch anything if I clean up outlet 2 and cap the free black wire is everything okay? Any ideas? 
Electrical – 3 sets of wires in outlet box, lights won’t turn off
electrical
Related Solutions
I suspect that one "set" of the red, black, and white wires is coming "in" the box, and the other "set" is going "out" of the box, downstream to another receptacle, fixture, or switch.
I don't see the harm in adding a third wire to each pair already there to bring power to the fan. Ground the fan properly.
First, your illustrations are Mad Awesome. You could illustrate electrical books. Literally. You might even talk to Mike Holt or others doing electrical docs.
You still have some knowledge gaps, so I'd school up some more. For a guy as smart as you, knowledge is cheap.
If you are good at visual, stay with that. Buy a variety-pack of electrical tape colors, and a couple feet of 12/3 cable because it's a cheap way to get a variety of wire colors for pigtails. 12 gauge is the universal donor size, it is acceptable on any common 120v circuit up to 20 amp breaker. 14ga is only allowed on 15A breakers/with 14ga wire.
First, permanently wrap (tag) the white wire of cable C with red tape. From your comments elsewhere that there is only one cable going to the switch, that is a switch loop. Also open up the switch box and wrap the other end of that same white wire.
Next, permanently wrap (tag) the black wire of cable A with red tape. Since the switch is a switch loop, this cable is the only possible way the lights could possibly be receiving (switched) power.
Now grab your receptacle and some stripped Romex and sit at a convenient workbench. Put 6" pigtails of wire as follows. Use the screw terminals or screw-and-clamp if you have that type. Avoid backstabs (they're not reliable) and never use 12AWG on a backstab.
- Ground terminal: a bare (or green) wire.
- screw 1: a white wire.
- screw 2: nothing, but if the tab between 1 and 2 has been broken, a white wire.
- screw 3: a black wire.
- screw 4: nothing, but if the tab between 3 and 4 is broken, a black wire.
Ready?
Splice all same colors together.
See, what I did was color-code all the wires to their function rather than the default colors of /2 cable. The switch loop has only hot (black) and switched-hot (red). The wire to the lights needs switched-hot (red) and real neutral (white).
In new work, they commonly use red for the switched hot, because the law now requires neutral in switch loops (for smart switches). So they run some /3 cable up there.
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Best Answer
You have hot wired your lights.
The light switch seems to be fed from the receptacle below it. (Cable C) So, the white wire on the switch should be re-identified as a hot wire with black, red or blue tape. It is now the hot feed to the switch. If this wire comes from the receptacle below it should also be re-identified there. The black wire in that same cable is the return leg from the switch. Your lights (Cable B) should be fed with the switch leg wire not the hot wire from the panel, and the neutral from Cable A.
In the receptacle box you should have a hot feed to the receptacle as one cable of the cables. (Cable A in your post.)
It sounds like the other cable (cable B) feeds your lights somehow. Strange way to wire it but from what you said that would be why your lights are now on all the time.
If you connected all the blacks and all the whites together in that box the lights would be on constant and the breaker would trip when you turn on the switch since it would now be a dead short. Since you didn't connect Cable C the switch does nothing at the moment.
Good luck and stay safe!