How can I rewire this circuit?

Question

In my basement, I am removing an existing fixture and planning on installing pot-lights. Previously when I have switched out a fixture, I generally find white + black + ground, which is pretty easy to deal with.

In this case, when I was removing my existing fixture, I found the following:

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One stand has White + Black, but the other has White + Black + Red. The two blacks are tied together and go nowhere. The two wites are tied together and go to the light, and the red goes to the light (where I generally would use a black).

My original plan, was to pull the wire back to the switch (along with the new wire that I would use for the potlights). But with two wires going to the fixture, I'm not sure where/what the other wire would be for. I can still pull one back to the fixture, but I would rather try to figure out what the other one may be for before I do anything like that.

Any ideas what the second line would be for? If I continue with my plan, of pulling the one wire back to the switch I should be able to replace it with new romex for the potlight, wire it up the same and have no problems?

Answer 1

This is how I suspect the circuit is wired, but you'll have to investigate to be sure.

In the fixture junction box:
White = Grounded (neutral) conductor.
Black = Ungrounded (hot) conductor.
Red = Switched ungrounded (hot) conductor.

The circuit may be wired this way because it continues on to feed other rooms, or simply because the switch is a "smart" switch that requires a grounded (neutral) conductor.

You'll learn a bit more about the circuit, when you open up the switch box and take a look inside. If you're still not sure what's going on, you'll have to probe the wires to gain a better understanding. If at any point you don't feel comfortable, or you're in over your head. Don't hesitate to contact a local license Electrician.

Answer 2

Here's my best guess. Power probably comes in on the 14/2 pair and leaves to the switch on the 14/3 wires. The switch if my guess is right will have the black and red wires attached to it and is probably done this was to feed another circuit.

Alternately the 14/3 wire could be providing switched power on the white/red pair and feeding another circuit (the 14/2 pair).

Answer 3

In switched situations, the traditional neutral (white) can be repurposed to a hot leg, though it must be marked.

You should be able to see the story at the switch.

In any case, cut power, disassemble connections, reenergize and carefully measure all the voltages with a helper at the switch. If it's not clear, please post the results of all wires with switch on then off and we'll diagnose.

This will tell you if this is a power at light or a power at switch.