One time at my job we had some electrical work that needed done. The electrician had a small homemade switch box with a 120v mains plug running out of it and a switch on the front. The device basically threw whatever breaker that plug was attached to so he new which one needed work on and made the circuit safe. Where can I get one of those boxes, or a way I can trip the breaker from the outlet?

  • Just as an aside, while it's not really possible or practical to test circuit breakers in situ it is possible to test RCDs using specialist equipment. This isn't done for identification purposes, however, but rather for testing and verification. – Dan Dec 30 '16 at 16:25
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    Is there a safe way you can trip a breaker from the outlet? No. What are you actually trying to do? – Mazura Dec 30 '16 at 22:30
  • Thanks everyone for your insite. It looks I'm just going to have to turn off the main switch and swap out these outlets. The guy that had this device wasn't the one that wired my house, but they are cut from the same cloth. I don't have much knowledge in house wiring so I wanted to ask before doing something stupid. I'm glad everyone pointed out its dangerous. I do have a Fluke tone generator/probe for cat5 so I suppose I could use that to trace the wire. – Brent1409 Jan 5 '17 at 5:17

The answer which states that this is a bad idea is correct.

To answer your actual question: you could build such a device in about five minutes. Take an extension cord, cut it in half, attach the white and black wires to an ordinary light switch, and wrap the whole thing in a handy box.

When plugged in and the switch is closed, a short circuit is created that will either trip the breaker if it is working, or start a fire inside the walls if it is not.

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    While you answered the question, I downvoted because you didn't but in big bold text, "THIS IS A TERRIBLE IDEA AND YOU RUN A HIGH RISK OF DAMAGING BREAKERS AND POTENTIALLY BURNING DOWN YOUR HOUSE" – Aloysius Defenestrate Dec 30 '16 at 17:08
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    @AloysiusDefenestrate My suggested edit as per meta.diy.stackexchange.com/a/661/21695 was rejected. – Andrew Leach Dec 30 '16 at 17:13
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    The answer clearly states that this is a bad idea and what the consequences are. I invite both of you to write your own answers that you like better. – Eric Lippert Dec 30 '16 at 17:14
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    I'm with Eric on this one. Stack exchange is polluted with answers that just say "don't." Sometimes I am looking for a bad idea. Not because I want to do it but because I want to understand how it works and why it is bad. By all means say "this is wrong," but at least answer the question. This answer didn't deserve a down vote. I don't think it is the best answer but I'm gonna upvote it so we don't punish answerers who answer the actual question asked. Also, @EricLippert, funny to run into you outside of stack overflow. – D. Patrick Jan 1 '17 at 0:21
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    @D.Patrick - "Sometimes I am looking for a bad idea." +1. I, myself, of course, have never made an outlet-popper... I mean um, a thingamajig whatchamacallit thingy. If you are going to use one; use your foot. You don't want your face anywhere near it. (This is if you have to ask territory. DVs should be directed at the question.) – Mazura Jan 4 '17 at 4:50

That box should have been a warning that the guy was incompetent; it's a very bad idea. If the breaker malfunctions, it can start a house fire.

There are cheap devices available in most home centers and hardware stores which can put a signal onto the wire and pick that up at the breaker to identify which breaker controls that outlet. There's a better version that a pro should have which can do a few other things.

Or there is the traditional homeowner solution: plug a radio into the outlet, turn up the volume so you can hear it from the basement, and try breakers until you find the one which silences the radio.

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    Also, once you have found the correct breaker, write it down somewhere, preferably close to the breakers. – SQB Dec 30 '16 at 14:18
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    You could make a device with a suitable resistor and fuse greater than the breaker which would be reasonably safe. But I agree with your conclusion. – Chris H Dec 30 '16 at 18:56
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    I think this answer would be better if it included a guess as to how the box worked and details on why it is unsafe. It mentions starting a fire but doesn't explain how or why that would happen. I don't know the OP's intent but it seems like that would make this answer complete. – D. Patrick Jan 1 '17 at 0:25
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    @D.Patrick: It is not something I want to encourage people to try. I cited the right answers. Use them. – keshlam Jan 1 '17 at 6:58
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    @kategregory, we will have to agree to strongly disagree on that one. Yes, working alone can be dangerous, but that's true of almost any task from gardening to cooking to you-name-it. The better solution is to work properly so things don't go wrong in the first place. House current can be dangerous, but following fairly basic rules does manage the risk for simple tasks to an acceptable level. And part of what we're here for is to answer questions about how to do so. – keshlam Jan 1 '17 at 14:41

That box works by connecting the live and neutral wires of the circuit to each other, i.e. it makes a short-circuit.
If all goes well, the fuse trips/blows. But as @keshlam said, it's a dangerous way to make a breaker trip: you're overloading the circuit. I did this once by accident, and had a 10 cm long flame blast out of the breaker box as the fuse tripped. Not the kind of thing you want to do on a regular basis.

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    Not to mention the extension cord could melt in your hands. – Dave Dec 30 '16 at 16:00
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    Exactly - it's kind of like testing your fire proofing by starting a fire. While things shouldn't go wrong if all is well, if all is not well there are multitude of possibilities - you could take out the main incoming fuse, the main circuit breaker (if applicable), an unknown fuse between (For example, some plugs in kitchens might be on a fused spur) among other things or maybe just start a good old fashioned fire. For the love of god, do NOT do this stuff deliberately. – Dan Dec 30 '16 at 16:29
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    Guys doing electrical work in our highschool did this. Put multimeter probes in each outlet, waited until the breaker tripped, and moved on to the next outlet (there was single breaker per outlet). – Cysioland Dec 30 '16 at 19:35
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    @Dan: In some cases there could be value in applying a moderate overload which should trip any properly-functioning breaker within a second, and ensuring that whether or not the breaker trips the overload won't last more than a few seconds. An overload which is small enough that a UL-approved breaker could take a second to trip shouldn't cause dangerous overheating in less than five. If things are wired correctly, stress-testing shouldn't be necessary, but if e.g. there's a connection between the hots coming out of two breakers, such a fault might allow part of a circuit to draw... – supercat Dec 30 '16 at 21:57
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    ...twice as much current as it should without tripping a breaker or worse--it could allow part of a circuit to draw four times the rated current while a breaker took as long to trip as it would for a 2x overload. Since a 4x overload would heat the wire four times as much as a 2x overload, that could easily get into dangerous territory. – supercat Dec 30 '16 at 22:00

The reason this isn't completely deranged at that industrial location is that certain industrial sites follow slightly more permissive rules owing to having on-site electricians with scheduled, proactive maintenance. You see this phraseology in certain NEC rules. Their work is done to a higher caliber than home wiring; THHN in metal conduit, no backstabs on the premises, frequent inspections, most circuits meggered, etc.

Doing this in a residential location with lax residential rules and work of unknown provenance is suicide.

Obviously the switch is basically dead-shorting the hot and neutral to induce a trip, but if you do that in a residence, you have about a 50/50 chance of inducing future arc faults at a backstab, or at the least, fusing it open. We get lots and lots of "plugged in a (well within legal range) large load and a backstab failed" questions. You also have a chance of other stupidity, like discovering why FPE and Zinsco panels are panela nongrata.


The safe answer to this would be to have an electrician install remote controlled circuit breakers, with a suitable trip circuit installed at the outlet where you want to remotely trip the breaker. (Eaton says they come in a CLR form factor for residential panels.)

Of course, properly labeling the panel, perhaps with a map showing where outlets/lights for each circuit would be a much cheaper and easier solution, and arguably more useful.

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