Thank you everybody for your input. Turns out, it had absolutely nothing to do with my shoddy wiring job (which I'll be cleaning up thanks to everybody's input). There was a switch on the opposite side of the hallway from my work that had a broken ground.


I had a wall outlet wired like the one below. I wanted to move it over about 4 feet, so I bought some electrical wire and used it to extend the existing wire.

(like this)

As you can see, it was two wires that needed to be extended.

Here's how I spliced the wires:

enter image description here

Basically, I twisted the bare wires together, then pigtailed them, wrapped each pair in electrical tape, then electrical taped the bigger white/yellow line pairs together.

I bought a new, standard duplex outlet and wired it up so that one extension wire was wired to the top outlets and one was wired to the bottom. I pig-tailed their grounds together with a third bare wire and connected the bare wire like this:

enter image description here


Everything was working fine for a few hours and suddenly a breaker on a different circuit tripped, shutting off the lights in the adjacent hallway. The new outlet that I had just installed still worked just fine.

Originally, I didn't break the metal break-off tab on the new outlet. While troubleshooting this, I broke it, still experienced the problem, and now the bottom plug doesn't work while the top one does.

I also tried swapping breakers to eliminate a bad breaker as the cause, but that didn't help, either.


  1. Is it possible that my wiring job caused this other breaker to trip. If so, how?
  2. If it is due to my wiring job, what can I do to fix it?

Edit - Panel Pics

enter image description here

enter image description here

  • if you had shorted something it would not take a few hours to happen, that is good. Now, was there something connected to the outlet during these "few hours" before the other breaker tripped? Also, if the breakers were connected in series (for some reason) the outlet would stop working, so it seems that they are not related a all.
    – jDAQ
    Sep 22, 2019 at 20:19
  • 2
    Wiring in one circuit would not cause a breaker in another circuit to trip unless the two circuits are not actually two separate circuits. It seems unlikely that you could have made an error that caused the problem, unless you have not revealed everything or disturbed something without realizing it. Could you have pulled on some other wiring or nicked some other wiring while cutting the new hole? You should probably open up all of the boxes and inspect the bad circuit.
    – Charles Cowie
    Sep 22, 2019 at 20:21
  • 1
    I'm concerned if you eliminated an outlet position you may have created a regulatory issue as well as a buried-splice issue. Do any of the circuit breakers involved have a "Test" button? Sep 22, 2019 at 20:57
  • 2
    It sounds like the GFCI is downline. Breaking off tab(s) would have severed power to it. Sep 22, 2019 at 21:52
  • 1
    @Harper Thought you might like to know that the issue was completely unrelated to my work; there was a broken ground in a switch on the opposite side of the hallway from where I was working. Complete coincidence. Thanks for your input and sanity check--I'll be cleaning up my wiring job and doing things the right way. Sep 24, 2019 at 17:41

5 Answers 5


I can't figure out the problem yet. Here's what I do know. And I have to save it because I can't visit chat without losing this.

So even though this isn't an answer answer, I find when troubleshooting problem A, if there are unresolved issues B, C and D out there also, they complicate things in unexpected ways, making it much more difficult to be sure where the problem is.

The old junction box MUST remain

It is not legal to remove that junction box. You are required to make all splices inside junction boxes, and cannot bury them inside walls (splices or junction boxes). Every junction box cover must be reachable without use of tools of any kind. You can make your extension splices inside the box, whether it has a blank cover or a receptacle.

It can have a blank cover, unless...

You need a receptacle within 6' of any point on a wall

You need to follow this wall its entire length between thresholds, (including around corners) and make sure there is still an outlet within 6' of every point along the wall. So, within 6' of a threshold and every 12' thereafter. This rule is because standard lamps and appliances have 6' cords, and you need to be able to route the cord hugging the wall (no cutting corners).

If you didn't have that situation before, the old situation may be grandfathered (legal now since it was legal when installed or modified). The rule with grandfathering is you can't make things worse. So if any area of the wall lost coverage because of the move, then you need to retain the receptacle at the old position. (You can still have the new one).

Mechanical execution of work

The lower picture looks perfectly proper. Wires must be 6" long past the cable clamp, and stick out 3" beyond the wall surface; don't get any shorter than that.

2 circuits or not?

If the first photo is of your actual box, it indicates that all wires are feeding the same socket of the receptacle. That means we can exclude "2 circuits" or "split switched outlet". For sure, the two blacks in the old photo are spliced to each other via the outlet. Ditto the two whites.

This means only one circuit is in play (assuming there are not wiring defects elsewhere) and you only needed one cable, not two, to extend this circuit. The other cable is superfluous. At the old box, all blacks can be joined at the old box with a wire nut, and all whites ditto. That will also reduce wire fill count to a sensible number.

If you need a receptacle at the old box, either avoid using the receptacle as a splice and use a pigtail to attach to the receptacle. Or use a "screw-to-clamp" type receptacle which gives four wire points per side. Do not use backstabs (as in first picture), because backstabs cause nuisance problems, with opens or arc faults; but also, backstabs can't work with 12 AWG wire, which is your yellow cable there.

The box must be large enough

For instance it appears your old box will have

  • four 14 AWG wires (judging by the backstabs) which take 2.00 cubic inches each
  • four 12 AWG wires, 2.25 c.i. Each
  • Pigtails are free
  • a bunch of grounds (which count as 1 of the largest wire) so 2.25 c.i.
  • cable clamps (which count as 1 of the largest wire) so 2.25 c.i.
  • if you have a receptacle, 2 of the largest wire connected to it. (4.50 c.i. If yellow jacket #12 wire is involved, otherwise 4.00 if using #14 pigtails.

If you need more cubic inches, before grabbing the claw bar, google "surface conduit starter box". It's for launching surface conduit out of a flushmount box, but if you only use it for cubic inches, I won't tell :)

  • 7
    Please refrain from stating something is legal or not without the jurisdiction. OP didn't specify it either, but set his profile to Seattle.
    – Nyos
    Sep 23, 2019 at 12:06
  • Every junction box cover must be reachable without use of tools of any kind surely this excludes a phillips head, right?
    – Brad
    Sep 23, 2019 at 15:37
  • 3
    @Brad The cover must be reachable without tools, not removable without tools.
    – JimmyJames
    Sep 23, 2019 at 15:49
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    I can't imagine how this could be but is there a possibility of a shared-neutral causing this symptom i.e. breaker flip on the adjacent circuit?
    – JimmyJames
    Sep 23, 2019 at 16:18
  • @JimmyJames ah gotcha
    – Brad
    Sep 23, 2019 at 16:36

Harper is absolutely correct that all junctions must be in a readily accessible box. This is both for safety and maintenance reasons - a junction hidden in a wall is both a fire hazard and potentially a headache for any potential future rewiring. The 6ft distance between receptacles is also required by code, but would only cause a fire hazard if it lead to a mess of extension cords being used (which is probably the cause for its addition to begin with, based on a lifetime of living in older houses that only had one receptacle per room).

I also recommend you twist your wire nuts more - the wires should visibly wrap around each other at least twice to ensure a reliably tight connection. Loose wires are a big headache, not to mention potential fire and shock hazards.

That metal tab on the side of your duplex receptacle is intended to connect the top and bottom receptacles in parallel. It only needs to be removed in the case that each receptacle has its own circuit, which is uncommon in residential wiring. That's why your bottom receptacle stopped working. You'll probably want to buy a new receptacle to avoid a mess of splicing.

However, to answer your question, I doubt that your wiring on one circuit caused another circuit to trip. I can't come up with a reason why that would occur. If swapping breakers didn't prevent the problem, it's probable that there's some sort of electrical fault happening on that circuit, or perhaps too much power is being drawn on it (is it only lights, or are there also receptacles on that circuit? If it's only lights, it's pretty unlikely that they're drawing too much power - but don't trust what the breaker box labels say, actually check to see if there are any receptacles not working while that breaker is tripped).


Harper and others made important points regarding the manner of work...there are reasons professional electricians spend years studying rules, and for those rules in the first place.

Note the afci breakers in the panel...if the one that tripped is one of those, it could be that arcing on a near by breaker has "fooled" it into tripping. This was an occasional issue with early AFCIs.

If that is the case, I'd consider any new appliances or changes as suspect.

If the circuit that tripped is the one with red flag...that is a multiwire branch circuit. If it's paired with the one you're working with, shut both off; firmly connect white wires of original wiring.


I have seen this issue where the 1st circuit breaker was less sensitive than the 2nd breaker. Having said that, your 'splicing' looks messy, especially it looks like you have bundled the ground(earth) with the other two lines. Also check if you have swapped the Line and Neutral, etc.

Are your breakers 'earth leakage' or 'current activated'? Earth leakage works when the Line (or sufficient Line voltage) enters/shorts to the ground wire. Current activated works on a basis of overload conditions, to be brief.

A schematic drawing will definitely help you. Also, you can try removing the 2nd breaker and testing to see if another breaker takes over the job.

Finally, try putting back the original circuit to see if the problem goes away, if it does then you need to RE-WIRE the new connection. Tip: ISOLATE all joints - Line, Neutral and Ground. Don't bundle them together.

Trust this helps.

  • 1
    Breakers and fuses are exceeding-current-activated. Trip switch (Residual-current devices, GFCI) are activated when current-in and current-out does not match (ground leakage). There are two types of a failure and there are two names for its anticipation.
    – Crowley
    Sep 23, 2019 at 11:54

Check ampere rating of Circuit breaker. You multiply how much wattage along the circuit load..doesnt matter about the wiring as long as it did in correct way.. One thing I observe I guess You exceed the total wattage value of the load in the circuit.. Use clamp meter.. And then you will notice. The real cause and problem to the circuit... Tips do not join lighting circuit to wall. Socket make it separate.

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