I installed new ceiling lights and one of them is not working. Nothing was existing, it was all new. I tapped into an existing electrical outlet, wired that to a new light switch, and then wired that to 4 lights, all daisy chained. It goes outlet > switch > light a > light b > light c > light d.

Everything works great when the wire to light d is not connected. If light d is connected, the breaker trips as soon as the switch is flipped. I thought it was a bad light so I bought a new one and replaced it. No luck. I've tried different light bulbs as well but nothing seems to work.

I inspected the wire from light c to light d and did not see any breaks.

Where should I go from here?

  • You're going to have to tell us a bit about how you wired it. Including what else is on the circuit, could be important information as well. – Tester101 Dec 12 '15 at 19:59
  • I have run everything right and then found a dead short in the end of the line, only to realize that one of my wire staples has pinched and shorted the cable. Tough to analyze if the run is completely covered. – bib Dec 12 '15 at 22:15

It's possible you have a short. From your question I don't know if you disconnected D by removing the connection at C or D. You could try this:

I'll assume since you did all this you're basically OK working with electrical. Get yourself a non contact voltage detector and use that through this whole process to confirm things are dead before you touch them.

  • With the breaker off, and the switch off, look at the wiring in the box at D. Look for any place the bare conductor of the hot wire could touch the bare ground wire, the neutral, or metal inside the box. Look for nicks in the wire, places where stripped wire extends past the wire nut, etc.

  • If that doesn't reveal anything, with the breaker and switch still off, remove the last light fixture (D) and cap the hot and neutral wires with wire nuts. Turn on the breaker, turn on the switch, see if it trips. If so, there is probably a short between the hot and neutral wires or hot and ground wires in the cable between C and D.

  • If it trips with the D light disconnected and the wires capped, turn the breaker and switch back off, remove the C fixture, undo the wiring and cap the wires that feed D, and reconnect C as if it was the last light in the line. Turn the breaker back on, turn the switch back on, and confirm that the breaker doesn't trip.

If it does, then something's not consistent. I'll assume it doesn't.

  • Turn off the breaker and switch again, and test for continuity between the hot and neutral wires from C to D, and between the hot and ground from C to D. If you see continuity with the wires disconnected and capped at both ends, you've found a short. The wire from C to D will have to be replaced.

If this doesn't lead you to a fix, you might want to call in for reinforcements, and leave that breaker off until they arrive.

  • First off, thanks for the detailed response. With the wiring from C to D disconnected at D and hot and neutral capped, lights A through C work fine and nothing trips. This is what lead me to try a new light fixture for D but it did not solve the issue. Should I still rewire C as if it is the last light in the line? – Lefka Dec 13 '15 at 11:49
  • Well, that means there's probably no short in the wire between C and D, which is good news. It seems like something must be happening in the box or in the fixture. I'll edit my answer with some more ideas. – batsplatsterson Dec 13 '15 at 12:02
  • It's a can light that mounts in the attic. That's what I replaced without success. There isn't anything else to replace at D. I think this is the actual one I have m.lowes.com/pd/… – Lefka Dec 13 '15 at 12:06
  • Can you install a temporary light in the attic at D? It's unlikely but not impossible you'd get two bad can lights. I'd double check the insulation at D, make the insulation isn't nicked, especially on the hot wire. Might be time for the reinforcements. – batsplatsterson Dec 13 '15 at 13:28

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