Tricks for tracking down a circuit breaker...

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sw_ross

Senior Member
Location
NoDak
Today doing work in a medium sized commercial building (typical EMT) I needed to turn a circuit off to change a bad gfi recep,
Multiple panels throughout bldg, none of them labeled other than "receptacles" or "lights", couldn't just start flipping breakers (building is the county courthouse/sheriff dept/EMS etc).
I have a simple Klein circuit tracer that works in very simple applications, the more complex the layout the less effective it is.
I'm definitely not a fan of shorting the circuit to trip the breaker but that's what it came down to.
Problem is, when I shorted the hot to ground (EMT) it would arc/spark but wouldn't trip.
I figured maybe the conduit has a loose connection somewhere and isn't an "effective" ground. So then I tried to short it to neutral, that wouldn't trip either!

I'm scratching my head trying to figure out why...
I hate using this technique ! I know it's dangerous and I'm sure I'll get criticized for doing it.
What other (safer) techniques are there?

Thanks!
 
G

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
171006-1950 EDT

Put a 10 A (about) resistive load on the circuit. Cycle this load on and off at about 1 to 2 seconds.

A small space heater would be a good load, but these use a fan and there may not be good enough circulation to prevent over heating the heating element. Also the fan motor may not tolerate this cycling. A larger space heater with no fan would be good.

Four 250 W bulbs will work. There may be some moderately small 750 to 1000 W IR heaters that might work.

There are various ways to cycle the load.

A Hall device magnetic sensor can be use to look for the cycling magnetic field close to the breaker. Also a 1" diameter, about 2000 turn, coil can be used as the magnetic probe.

The on-off cycle time would be based on how fast the meter from the probe responds.

This method does not require opening the breaker panel.

.
 
M

MAC702

Senior Member
Location
Clark County, NV
sw_ross said:
... I know it's dangerous and I'm sure I'll get criticized for doing it....
Click to expand...

Um, yeah, about that....

I've been known to charge triple and change it live...

That might get me run out of here... :eek:

The Ideal circuit breaker identifying tool is crap. The Greenlee Circuit Seeker is outstanding, MOST of the time, but not always.
 
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MAC702

Senior Member
Location
Clark County, NV
Sorry. I used to be poor, and didn't expect a $90 tool from a major manufacturer of industrial electrical tools to be a Kiddie Box version at the time. But I can confirm they are crap. Sad to see Ideal with their name on such a piece of crap.

The one you show looks pretty much like the Greenlee. I wonder which came first? Thanks!
 
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sw_ross

Senior Member
Location
NoDak
Ideal Suretracer

Ideal Suretracer

I've looked at those ideal circuit tracers. Kindve expensive, but it would be worth it in situations like I dealt with today if they work as advertised!

Do they work well in commercial applications with multiple panels located on various levels, all in EMT?
 
roger

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
MAC702 said:
The one you show looks pretty much like the Greenlee. I wonder which came first? Thanks!
Click to expand...
Don't know who was first but we were using them around 2007 and the price tag then was in the $600 to $700 range but even with that they were worth every penny in large commercial and hospital projects.

Roger
 
Jraef

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
For a remodel job I did last year, I bought a Zircon Circuit Breaker Finder. It worked 100% for my purposes. In my case, it even picked out the correct twin breaker.

But exactly as they say, it needs a FRESH 9V battery, and you MUST scan the panel twice; it WILL give false positives on the first pass, but not on the second.
I didn't get the "Pro" version, the difference was that it works on 208-240V circuits and has a bunch of adapters that I wasn't going to use, so I didn't bother.
 
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sw_ross

Senior Member
Location
NoDak
Another tangent to this gfi changeout ...

Another tangent to this gfi changeout ...

Another side story to this scenario of changing out the gfci Recep is that I ended up changing it out live (I know...de-merits....), anyways, I couldn't get the new gfci to trip either...
A head scratcher... I even plugged an extension cord in and went to the female end of the cord and shorted it out Li->N, it didn't trip the gfci!

I'll be going back there Monday morning and do more troubleshooting.
 
M

MAC702

Senior Member
Location
Clark County, NV
sw_ross said:
I've looked at those ideal circuit tracers. Kindve expensive, but it would be worth it in situations like I dealt with today if they work as advertised!

Do they work well in commercial applications with multiple panels located on various levels, all in EMT?
Click to expand...

I trust Roger to assume they must work as good as the Greenlee Circuit Seeker. I spent my last $700 on mine at the time, but it got the job done, and has been working when I need it for the last twelve years.

They will not scan through grounded metallic conduits. But it will find the breaker at the other end. In reality, finding breakers (or ID'ing a cable in a bundle) is about the easiest thing you can do with these tools. They will also find breaks and shorts in non-metallic cables in walls if not too deep.
 
M

MAC702

Senior Member
Location
Clark County, NV
sw_ross said:
Another side story to this scenario of changing out the gfci Recep is that I ended up changing it out live (I know...de-merits....), anyways, I couldn't get the new gfci to trip either...
A head scratcher... I even plugged an extension cord in and went to the female end of the cord and shorted it out Li->N, it didn't trip the gfci!

I'll be going back there Monday morning and do more troubleshooting.
Click to expand...

Did you confirm it was properly wired the first time, in case you just copied it, and has a good 120V?

Line -> Neutral won't trip a GFCI, but it should trip the breaker, but that didn't trip last time, so you do have another job there to go get...

Line -> Ground should trip your GFCI, even if it doesn't trip the breaker.
 
C

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
If you're in this for the long haul, then it makes sense to own(or rent) the proper tools, no matter what they cost in my opinion. Most places would fire you if they knew you shorted something like that.

I have a higher end Amprobe AT-2005 that works well as breaker finder. Bought lightly used on Ebay 7 years or so ago for $500. That's a little over $70/year to have that tool, with that cost going down every year I have it. I can't see how a person can't see the value in owning a GOOD circuit tracer/breaker finder or any good tool for that matter when you look at the cost of ownership over the time you have it..
 
ActionDave

ActionDave

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Location
Durango, CO, 10 h 20 min from the winged horses.
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Licensed Electrician
Cow said:
....I have a higher end Amprobe AT-2005 that works well as breaker finder. Bought lightly used on Ebay 7 years or so ago for $500. That's a little over $70/year to have that tool, with that cost going down every year I have it. I can't see how a person can't see the value in owning a GOOD circuit tracer/breaker finder or any good tool for that matter when you look at the cost of ownership over the time you have it..
Click to expand...

I'm a big fan of the Amprobe too. I've used the Greenlee and it's a decent tracer but I hate the auto squelching that our model has. Never used the Sure Trace.

I have used the light bulb and amp meter. I prefer my heat gun and amp meter.
 
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