Separate Circuit Indicator / Breaker Finder

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  #1  
Old 11-30-15, 08:50 PM
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Separate Circuit Indicator / Breaker Finder

Hi all,

I am no stranger to electrical work. I've done lots of my own home electrical work, some for friends, and I also deal with high voltage 3-phase loads for audio-video production work regularly.

This post has more to do with work electrical issues. For production work, we often go from venue to venue and bring in a lot of AV gear. Venues are often clueless about their electrical setup, which receptacles are on which breakers, etc. I own breaker tracers to find them if you know which panel they are on.. but usually, we're more concerned about receptacles being separate circuits or breakers than where those breakers actually are.

So, I've been searching for something inexpensive that I can plug into 2 receptacles and know if they are the same branch circuit. It would be nice if that same tool or kit also had breaker finder but it is appearing that is a different product.

The only thing I came across searching the web is this Breaker Buster tool. $60 isn't bad, but is this something I can make myself? How does it work? There's also a Breaker Buddy II floating around that looks smaller, but is the same.

While this would work fine, it does require an extension cord to get to a distant outlet. Are there any wireless kits that have multiple "tracers" that could do the same sort of thing without access to a breaker panel?
 
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Old 11-30-15, 09:40 PM
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Welcome to the club. I rent out sound systems so I know exactly what you are talking about. I get to work in schools. Where there is 0 to no power.

Those devices you linked to won't help. Those work by showing different legs of the service.
Actually... I think that light works when it sees 200v or above.

Let me see if I can explain. If you had one receptacle on the A phase and one receptacle on the B phase..... that device would show a light. So in that instance you are on different circuits.

If you had one receptacle on phase A circuit one and another receptacle on phase A circuit 7 the light wouldn't work. You're on two different circuits but the same phase.

Can you make it yourself.... sure. It's an indicator that lights when it gets over maybe 200vac and is connected between the two hot (small) legs of each plug.
 
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Old 11-30-15, 10:04 PM
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Make a box with two cord sets. Install two banana jacks in the box. Connect only the narrow blade of the plugs one to each banana jack. Plug in the cords and make your measurement. For safety always remove the meter between measurements. This reduces the danger of the suicide cords in your first link.

A plan B would be two keyless lamp holders in series with a 120v incandescent bubs of equal wattage in each. For safety the narrow blade of one plug would be connected through a NO momentary contact switch. The other side of the series directly to the narrow blade of the other plug. Plug it in and push the button. Full bright on different legs. No light same leg. Or just use one 240 volt bulb.
 
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Old 11-30-15, 10:21 PM
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Oh, so that makes more sense.. They just measure 208-240v across different phases, so it doesn't do any good on different or same breakers of the same phase...

Any of the sniffers work for this?
 
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Old 11-30-15, 10:59 PM
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No.... there is no miracle way to determine what is on each circuit other than tripping it and testing.

The device you linked to looks like a suicide cord setup but they use a very low current indicating device.... maybe even a neon lamp.
 
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Old 12-01-15, 07:01 AM
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It boggles my mind that with all of the testers, tracers, etc out there that this can't be accomplished.

At the VERY least, it seams like a tracer system could be devised that measures propagation delay between a transmitter and a receiver. Since 99.99% of the time multiple receptacles are on the same branch circuit, the receptacles are daisy chained together (or in commercial setup, there's a J-box), we should be able to see that the transmitted signal only travels 25' and not say 90' to a breaker panel and BACK to another circuit.

I know it is a very different animal but I use a Fluke MicroScanner2 for my CAT5/CAT6 testing needs and that sucker tells me way more than I ever need to know... length of each pair, shorts, missing pins, which end of the wire terms a problem is, ID number of the remotes, etc...

I realize AC is a different beast, neutrals are shared, grounds are shared (and usually tied to neutral), etc.
 
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Old 12-01-15, 11:53 AM
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The problem is that two breakers (on the same leg) are electrically exactly the same. You'd need to pull 30A to actually trip a single breaker to 'prove' it's not the same breaker.

I like your idea of determining the length of the wire, but the technology to do that is still quite expensive, would be difficult (impossible?) to do on a live AC wire. They work using time delay reflectometry, picture basically the way sonar works, bouncing a sound (or pulse of electricity) and listening for it's return. I'd imagine it would be difficult to do in the high harmonic state of AC power. Plus, even if you could do it, you'd see that it's 100' of wire between receptacle A and B... which could be to the breaker box, or some convoluted routing because of the way the conduit was originally run.

I'll admit, it's an interesting idea...

On a side note, I'm impressed that the Microscanner 2 is only about $500. When I started using the original Microscanner, it was about $5K... but still pretty awesome.

----

After a 20 minute Google sidetrack... looks like something may already exist:
FaultChaser: Find open and short circuits on faulty wiring › LiveWire Innovation
It's not specifically advertised to do this, but maybe?
 
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Old 12-01-15, 09:28 PM
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I too remember the HIGH cost of the Microscanner.

That Livewire tool looks interesting. No retail prices anywhere to be found on the web. Many aviation companies endorse/sell it. That tells me it's expensive.

It's basically a HD TDR unit. Not really much help in this problem. (I still want one )
You can read length of wire live but how will that tell you which receptacle is on which circuit ?
 
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Old 12-02-15, 08:10 AM
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I can't imagine TDR would really be useful on AC light/receptacle circuits which are spliced and/or branched every ~12 feet. The curve would look so wonky it would be impossible to interpret. Much different than continuous point to point telecom cabling or long underground power feeders.
 
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