I'm replacing a single overhead light in a bedroom with recessed lights. In the junction box for the light were other junctions that fed electricity to the outlets in the room. The wire that came from the wall switch was a 3 stranded wire that went from the wall switch to the junction box for the light. When I dropped the light down there were other junctions which seem to feed the outlets in the room. So there were 3 things going on. Two white wires were connected and tape wrapped. Three Black wires were tape wrapped together with a long lead that connected to the black wire on the light. Then there was a white wire with red bands connected to the white lead of the light. The switch turns the light on and off but doesn't affect the outlets.
After cutting the power, I removed the light and disconnected the remaining wires. I cut the switch wire back as it had reached the middle of the room and I didn't need that much wire to reach the recessed lights. I installed the recessed lights and connected them together as instructions showed. I connected the switch wire with red-banded white going to the white quick connect (as it HAD been connected to the white on the old light), I put the black in the black quick connect. I also added a length of 14-2, putting the black wire in the quick connect, and wire nutted the remaining white wire from the switch inside the can light. I then took the wire to a new junction box and connected all the whites and all the blacks together to power the outlets.
When I energized the circuit, I got power to the outlets, and in testing with a circuit tester, everything else seem hot. I put a light in a can to test the switch but the light did not turn on. Everything else seems good. What's the best way to figure out what I did wrong?
Best Answer
You probably know this already, but the purpose of a switch is to break the "loop" of electricity that feeds the lights.
Find out where all your wires come from and go to, draw a picture of the circuit and that should narrow down your problem or at least help you in describing your problem to someone who could help you. Drawings are very helpful for issues like this.
From your description, it sounds like the black (hot) wire to the original light was not switched, but the white (neutral) wire was the break in the circuit via the switch. If you wired your can lights up with this in mind, and things still did not work, then there is something else going on that you need to do some investigating to see why your original assumption of where the wires go to/from failed. One of those wires doesn't go where you think it does, or the white/red wire that goes through the switch is not in the same "loop" as the black wire (not likely, nor really possible, but not impossible).
This might be a good opportunity to put the light and the outlets on different circuits. I think that may even be required by code. (ThreePhaseEel suggests that this is only required in bathrooms and kitchens, not necessarily for bedrooms.)
One way to check if you have the same wire (or branch of a circuit) at both ends is to flip the breaker, ground one side of your wire in question to something grounded (pipe, conduit, green ground wire, etc.) and measure with a multimeter that you have 0 Ohms of resistance to ground at the other end (i.e. place one probe on your wire and the other probe on somethign that's grounded...pipe, conduit, green ground wire, etc.). undo the ground and your resistance should go to infinity (or OVLD or something similar). There are also helpful circuit finding tools that would do this same trick...check amazon.