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Rudimentary Wiring Diagram

I'm installing recessed lighting around my living room. I pulled power for these lights from an outlet circuit in the same room (see bottom right of photo). Everything was going according to plan, until I cut some excess wire with the breaker on but switch off. I'm no electrician, obviously. I thought this would be all right, since the wire was not activating my voltage tester when I installed the fourth recessed light in the ceiling. Nevertheless, when I snipped off the excess wire on the sixth light, the breaker tripped and all recessed lights as well as the devices plugged into the outlets around the room stopped working.

  • The first thing I did was reset the breaker (twice), nothing works.

  • Next, I used a multimeter to test Outlet 1 (hot to neutral, hot to ground), and I get a reading of ~250 millivolts but the voltage tester stays silent.

  • Then I removed the outlet and used the voltage tester and multimeter directly on the wires coming into the outlet. Same result.

I'm almost certain the outlets (and recessed lights) receive power from a two-wire line (dashed orange line) tied into a hot bundle inside the box holding the three-way switch nearest the first recessed light. All wires appear undamaged, and each one set off my voltage tester. But this confuses me, because if there's power in that box and not at Outlet 1, then the problem must lie in that wire. Right? I hope that's wrong, because that would mean tearing out a lot of drywall to replace that wire. It seems crazy that cutting the wire all the way at the end of the circuit could somehow damage the middle of the first wire run in the circuit.

What am I missing? Also, what even happened here? With the switch off, how was that wire at the end of a string of lights energized?

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It's very unlikely the wiring in the walls was damaged. Usually what happens is a weak connection gets fried by the short circuit. As many others have mentioned previously here, these failures are often the result of the infamous "back stab" outlets. You might have to take out several of them (WITH THE POWER OFF) and inspect for loose connections or obvious damage. If no damage found and the outlets removed and carefully placed, turn the power back on and start testing.

To clarify, did you get a spark when you cut the excess wire? I would have been quite noticeable. Also, what type of breaker is it? Arc fault? Ground fault? Did you test at the breaker panel to see if you have power coming out of the breaker?

This may take some detective work here, but to allay your fear, it's not likely a failure of wires in the wall.

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    Also meant to mention is why cutting the cable with the switch off would trip the breaker? we need to know the type of breaker to give you good advice. I'm worried that somehow you mis-wired the lights downstream of the switch...IE: Maybe switching the neutral instead of the hot? This could cause a short to ground resulting in a tripped breaker. – George Anderson Mar 22 at 3:51
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Thank you for your helpful feedback. My problem was an outdoor GFCI receptacle in line before the interior receptacle labeled Outlet 1 in my drawing.

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  • The downstream outlets probably shouldn't be connected to the GFCI load circuit unless they're in wet locations. You might correct that to prevent future hassle. Just bypass the outlet in that box. – isherwood Mar 23 at 14:44
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    I believe current code requires outdoor outlets to be on their own circuit, not tied in with interior circuits....not that you are required to upgrade, just saying. isherwood is right. How you would do that is rewire the outdoor GFCI outlet connecting the outgoing cable to "outlet 1" to the line side, not the load side, assuming there are no other outdoor outlets protected by the GFCI. Even if so, you could replace the other outlet with another GFCI outlet. That way the interior circuits are not GFCI protected eliminating bothersome trips turning off outlets and lights in the house. – George Anderson Mar 23 at 15:03

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