Circuit breaker finder

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Fred B

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
I was wondering if anyone has a circuit breaker finder/tracer that actually works with high reliability/accuracy? I've had and used a southwire circuit breaker finder for a number of years but find it very unreliable particularly on older installations or MWBC, a lot of false locations. With so many working from home and accidentally shutting down circuit for their computer or phone line modem a much greater problem. Am a 1 man operation and getting older and multiple trips to basement from second floor to verify the correct circuit is not on my favorite thing to do, so a reliable tester would be great.
 
I bought a cheaper one recently, don't remember the brand (may well have been Southwire) that you first pass over every breaker, ignoring the light/tone, then go back over them a second time. The first pass must be a calibration/sensitivity adjustment, as it clearly identified only the correct breaker on the second pass.
 
I’ve had the Zircon breaker tracer for years.

It works like the one Larry has.

Hasnt given me a false or failed to find the breaker yet. I use it constantly.

I intend to pick up the SureTrace 959? I think it is, just for increased versatility. But for just tracing breakers, the Zircon is great.
 
For a cheap tracer, the Zircons work great. As others have said, you scan the panel twice, and it will eliminate the false readings. Two key things to remember when using the Zircon, is never test it at the transmitter before scanning for breakers. It looks for the strongest signal, so that’s why you have to scan the panel twice. If you scan it at the transmitter, it will not find the stronger signal, and will not reliably locate the breaker. Second thing, is to use the plug adapter that allows you to connect only to the hot, then you take the other lead to ground. Greatly strengthens the signal.
 
201031-2041 EDT

One way that should be reliable is:
1: Put an oscillating load of about 10 A ( a space heater ), 2 sec on and 2 sec off, on the circuit to be found.
2: Look for that oscillating current in the breaker panel. It will appear on only one branch circuit wire unless there is some wiring error. If there is a wiring error this test will find it.

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I use a Klein circuit finder. I'm on my second one because the first one I had, I accidentally left the plug-in at a house.

Well, the first one was a whole heckuva lot more reliable than the latest one....different look/style, may be different technology? 🤷‍♂️

I really never had a issue with the older one. But the newer one is finicky or something.

With Cutler Hammer CH brrakers, I have to take the panel cover off and scan the wires.

Recently I verified/relabeled 11 panels in an old Ryan's Steakhouse, all SquareD QO and zero issues with covers on.

It's a crapshoot. Id love to find something else. Maybe the Zircons a couple have mentioned
 
201101-1015 EST

With my about 10 A space heater I get somewhat more than an 0.1 V change across my 20 A QO breaker. Easily identified with an oscillating signal known exactly load. This same signal will not occur on any other breaker.

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I also use the Klien, it’s not perfect. Does not work well with GFCI and AFCI breaker’s. But it does get you close when you are re-labeling a panel


“ shoot low boys their riding shetland ponies”
 
Ideal sure trace.

I work at a large facility over 500 panels in one building alone, I would say over 99% Accurate, on identification of receptacles. Also have the live clamp induction accessory and works well for 480v Tracing.


Sent from my iPhone using Tapatalk
 
I have a Greenlee tracer that I have had for maybe 25 years. The receiving unit has a high range and a low range. High range does not work for finding a breaker, can sort of work to trace wiring inside wall, but to do so you need an alternate and known return path (usually an extension cord run back to or near the panel) so you are only tracing one conductor of the circuit you are trying to trace.

It also has variable fine trim adjustment. Some cases you can find which conductor you are tracing pretty quick, others you have similar signal on more than one, you need to trim it down until you only get a signal on one conductor, you have to be a little patient or else you still end up assuming you found it when you did not and end up turning off something you weren't intending to. This unit cost me around $300 IIRC but was about 25 years ago. It can be connected to AC or DC and up to 300 volts, have traced some 277 (or 480 by tracing one line to ground as long as not over 300) with it and works fine.
 
I’ve used Amprobe circuit tracers for about 30 years now. Deadly accurate because they draw current off the line instead of injecting a signal which tends to bleed off to other circuits. I can pull a single wire out of a bundle of 100 with 99.9 % accuracy. The drawback, unlike the Ideal and Greenlee tracers, is it only traces live circuits. But due to that, it’s accuracy is much greater. Cost almost twice as much too though!
 
I haven't done residential work for 40 years other than friends and family, but when I did, none of that fancy stuff existed. We just plugged in an old AM portable radio tuned to our favorite Top 40 station, cranked the volume and when you turned off the right breaker, you hear it go silent. I did this about a year ago at a relative's rental house in the California Central Valley and discovered that the only thing on AM radio any more are Mexican music stations and religious broadcasts.
 
201102-1731 EDT

With my cycling load method one does not need to, and can not, shut power off to the circuit being looked for. Even with a 1000 W load at 120 V, about 8.3 A, I can find the circuit on a 40 A QO breaker by looking for breaker voltage drop change.

Using a Fluke 27 I feel that 4 seconds on and 4 seconds off is a minimum timing cycle. This is because of the averaging time constant of the meter. Using a scope the cycle rate could be very much higher. Possible 64 mS. A Simpson 260 would be faster than the Fluke 27, but without added circuity could not tolerate 250 V and still read in the 10s of mV.

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gar said:
201102-1731 EDT

With my cycling load method one does not need to, and can not, shut power off to the circuit being looked for. Even with a 1000 W load at 120 V, about 8.3 A, I can find the circuit on a 40 A QO breaker by looking for breaker voltage drop change.

Using a Fluke 27 I feel that 4 seconds on and 4 seconds off is a minimum timing cycle. This is because of the averaging time constant of the meter. Using a scope the cycle rate could be very much higher. Possible 64 mS. A Simpson 260 would be faster than the Fluke 27, but without added circuity could not tolerate 250 V and still read in the 10s of mV.
Click to expand...
If I understand use of a scope it would require access to the wire inside panel and the breaker terminal, is that correct? If so that method would be prohibited at some venues I have worked. They require hot work permit to remove panel cover and require a lot of substantiation to get a permit, so a quality circuit finder that I can count on its accuracy would be good to have.
I do find your method interesting but I don't have a scope, haven't seen a need yet to justify the cost with what most of the work I am doing is single phase residential. Maybe someone can convince me of the need for a thousands dollar peice of equipment.
The only experience I've had with a scope is in motor testing. Also reading a thread here that seemed to take them around in circles using a scope trying to diagnose a problem, kind of dampened any thought of investing in one or to see the value.
 
Ideal SureTrace hands down.
Kindve expensive but well worth the investment.
i do service work in a number of commercial situations. The last thing you want to do is Accidentally turn off the circuit that feeds the receptacles for the computers at the sheriff’s office!!
I have high confidence with the ideal that I’m not going to turn off the wrong breaker.
It’s also great for a lot of other troubleshooting applications regarding tracing wires and circuits.
Do a search on YouTube and watch some of the videos.

I’m so reliant on mine if I lost it or broke it I would immediately order another one. I use it daily for service calls.
 
I used to do a lot of work in data centers, turning off the wrong breaker is not an option. The deadly accuracy of the Amprobe is a must. The Ideal and Greenlee tracers are good, but not as good as the Amprobe.
 
gar said:
201102-1731 EDT

With my cycling load method one does not need to, and can not, shut power off to the circuit being looked for. Even with a 1000 W load at 120 V, about 8.3 A, I can find the circuit on a 40 A QO breaker by looking for breaker voltage drop change.

Using a Fluke 27 I feel that 4 seconds on and 4 seconds off is a minimum timing cycle. This is because of the averaging time constant of the meter. Using a scope the cycle rate could be very much higher. Possible 64 mS. A Simpson 260 would be faster than the Fluke 27, but without added circuity could not tolerate 250 V and still read in the 10s of mV.

.
Click to expand...
Gar, your method is an excellent way to find the breaker for a circuit if in the right circumstances. Where most of us need something is out in the field and we can't carry around scopes or space heaters. We need an instrument that is portable and also reliable.
 
Jraef said:
I haven't done residential work for 40 years other than friends and family, but when I did, none of that fancy stuff existed. We just plugged in an old AM portable radio tuned to our favorite Top 40 station, cranked the volume and when you turned off the right breaker, you hear it go silent. I did this about a year ago at a relative's rental house in the California Central Valley and discovered that the only thing on AM radio any more are Mexican music stations and religious broadcasts.
Click to expand...
Not a good choice if you absolutely positively cannot turn off certain circuits
 
201103-0914 EST

Fred B:

With the oscillating load method I can use a magnetic field sensor, a coil, and sense current from the outside face of a breaker. Less positionally accurate than the breaker voltage drop approach.

If I run a separate return current path for a circuit, then I can trace a wire some distance from the wire, and even in conduit with a magnetic field sensor. If I add a phase sensitive detector, correlation detector, then I can detect the direction of power flow.

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Jraef said:
I haven't done residential work for 40 years other than friends and family, but when I did, none of that fancy stuff existed. We just plugged in an old AM portable radio tuned to our favorite Top 40 station, cranked the volume and when you turned off the right breaker, you hear it go silent. I did this about a year ago at a relative's rental house in the California Central Valley and discovered that the only thing on AM radio any more are Mexican music stations and religious broadcasts.
Click to expand...
And talk shows of various topics.
 
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