# Tracing 3 ph circuits



## wirenuter (Oct 19, 2009)

Any ideas for tracing 3ph circuits. We need to locate CBs in a number of different MDPs and dont want to deenergize. Voltages range from 120, 208, 277, 480. !00 - 200 amps
Any tricks?


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## Mr. Sparkle (Jan 27, 2009)

T & M is the first step.


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## Mr Rewire (Jan 15, 2011)

wirenuter said:


> Any ideas for tracing 3ph circuits. We need to locate CBs in a number of different MDPs and dont want to deenergize. Voltages range from 120, 208, 277, 480. !00 - 200 amps
> Any tricks?


 Circuit tracer.


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## Dierte (May 12, 2009)

Mr Rewire said:


> Circuit tracer.


 Ditto yo, my circuit tracer is worth its weight in gold.


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## mdfriday (May 14, 2007)

wirenuter said:


> Any ideas for tracing 3ph circuits. We need to locate CBs in a number of different MDPs and dont want to deenergize. Voltages range from 120, 208, 277, 480. !00 - 200 amps
> Any tricks?


How do you have a 120v 3 phase circuit?

Follow conduits if you do not have a circuit tracer.


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## pawirenut (May 28, 2008)

mdfriday said:


> How do you have a 120v 3 phase circuit?
> 
> Follow conduits if you do not have a circuit tracer.


There are alot 120/208v branch panels in commercial buildings. You get 120v off of one leg.


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## wirenuter (Oct 19, 2009)

pawirenut said:


> There are alot 120/208v branch panels in commercial buildings. You get 120v off of one leg.


Right. And I have a 120v circuit Tracer, but it wont work on the higher voltages, and these thing in my experience are not all that accuate unless you can kill the power and lose the tone.


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## 480sparky (Sep 20, 2007)

3-phase circuits are usually dedicated circuits. Motors, air handlers, etc. It's rare that a 3-phase circuit ends up in several locations.


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## Foestauf (Jan 5, 2011)

In one of my older threads I listed an ideal circuit tracer works up to 600v. 
Cost is about 700.


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## MDShunk (Jan 7, 2007)

The 480 circuits shouldn't be too hateful. You can follow the pipes from those. They probably mostly all end up at RTU's, xfmr's, or big motors. The 277 stuff... well, that might be tricky. The 120/240 stuff you can do with any tracer. 

By the way, I prefer the Amprobe AT-2005


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## mdfriday (May 14, 2007)

pawirenut said:


> There are alot 120/208v branch panels in commercial buildings. You get 120v off of one leg.


Yup, but how do you get a 120 v , 3 phase ckt?


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## MDShunk (Jan 7, 2007)

mdfriday said:


> Yup, but how do you get a 120 v , 3 phase ckt?


With a pretty special transformer, I suppose.


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## 480sparky (Sep 20, 2007)

mdfriday said:


> Yup, but how do you get a 120 v , 3 phase ckt?


With a transformer like what's in the middle of this pix:












Nameplate of said transformer:








​


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## mdfriday (May 14, 2007)

Hmmm..... thought if you had a three phase load, it would be 208, 240, etc, etc, never heard of a 120v three phase load / ckt

the transformer is 120/208...


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## erics37 (May 7, 2009)

I have a couple little adapter thingies I've made for my 120V circuit tracer. A couple of them plug into twist-loks of varying types, one of them can screw into a light socket.

If you hook a regular circuit tracer onto just one of the 120 volt legs and the neutral that'll trace you back to the 3-pole breaker that feeds it all.

And by circuit tracer I don't mean a toner.


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## Malaking_TT (Dec 17, 2010)

Dierte said:


> Ditto yo, my circuit tracer is worth its weight in gold.


I bet you could re-sell it for quite a nice profit.


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## macmikeman (Jan 23, 2007)

Another option to trace loads is to cycle on and off the load and check the front end with amprobe meter. If you have a boatload of individual branch breakers and not that much time you can check the feeder and it will show up there as well. Then you can start going thru each branch breaker in the panel and eventually you get to the one in question. Certain machines do not like to be treated in this rude manner however so individual results may vary....


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## Foestauf (Jan 5, 2011)

Ideal 61-956 is the circuit tracer I use, love it.


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## gfunkatoa (May 13, 2021)

Old Topic. New device. Anyone out there using a AMPROBE AT-8030?


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