Finding Panel feed circuit with no power to bldg.


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Old 03-10-14, 02:48 PM
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Finding Panel feed circuit with no power to bldg.

I'm fixing up an old abandoned building with (no power on it). It has some wiring left amiss when previous renter left. I have this one J-box with several entries that were not connected. I've been able to trace (visually and with a continuity tester) and isolate all but one of the entries into this J-Box.

The ones I've found for sure are
(1)an outlet (recept) circuit, found the J-box wire pair by putting a jumper wire in the recept (hot to neutral) and ringing all the wires in the J-box till I found the correct pair.

(2)a switch leg going to nearby switch, found this J-Box pair by ring tests showing on and off depending on flipping switch.

(3)Two more (2-wire) circuits (one to a light and the other to a ceiling fan) that I surmise these should hook the switch leg (and neutral). There was a good bulb in the light circuit so it rang from 2 wires in the J-box, and the fan J-Box wires rung after I pulled the chain on the fan (or not).

Now none of the above pairs rung when tested to any other wire in the J-box. So each pair was isolated.

Also (as far as I'm concerned) there is no reason to add the recept circuit to the switch, so it will just wire to the panel home feed circuit, which brings me to the last undetermined pair and my question.

There is only one unaccounted for pair of wires left in the J-box so I thought this is probably the home feed circuit back to the panel. I had planned to wire nut these two J-box wires temporally together (remember there is no power on the bldg) and then go back to the panel, turn off all breakers and continuity test between each wire going in a breaker and the neutral bar till I found the one that rung.

However while still at the J-box I noticed that these two last wires rang continuity "at the J-box" (no they did not ring with any of the previous isolated wires). This made me wonder, I did not see how this could be a home run and yet ring at the J-box ? I mean the two Panel single phase bus bars are not connected to the neutral bar so I was confused. So still wondering I went to the panel and noticed all the breakers were flipped on. I went ahead and flipped them all off and went back to the J-box and rung the suspected home run pair again. This time they did not ring.

Now I'm not an electrician, I just know how to wire some things, so please excuse my ignorance if I'm missing something. But how can these wires ring with the breaker on ?

Just to make sure I went back turned all the breakers back on and went back and rung the said last J-box pair, they rang continuity again.

It was getting near dark so I picked up my tools and came home. I will go back again sometime this week and do more testing. I'm thinking it's tied somehow into the way the local power company turns the service off. They don't disconnect the service wires at the weather head anymore. Rather they pull the meter and put in a smart box. And if anyone messes with this smart box to try and steal power it sends a signal back to the power company and they call the cops. I "guessing" that they have the load side hookups jumped to the load neutral hookup, that way I would get a ring as I was.

Appreciate any and all input on this. If I have not made myself clear please tell me where to clarify.
 
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Old 03-10-14, 10:56 PM
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Are there any incandescent light bulbs in this place? If switch controlled could the switch be turned on? Depending on what you are using to "ring out" these circuits a branch circuit supply from the circuit breaker panel could very well show continuity between the "hot" and neutral leads if all the CBs are closed and there is a light bulb in any circuit. The continuity would be from the tester to the branch CB to the panel bus through a second CB to the light bulb to the neutral conductor back to the neutral bus in the panel and finally through the neutral conductor back to the tester. If this is the case then there should be TWO circuit breakers that could interrupt the circuit, the one on the branch circuit you are testing and the one on the branch circuit of the light bulb.

There could be other loads that would mimic the same action such as a smoke detector, a doorbell transformer or several other loads depending on the specific tester being used. It is possible that even the circuitry in a GFCI receptacle might trigger some testers.
 
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Old 03-11-14, 07:22 AM
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Thanks for the reply Furd
[-Are there any incandescent light bulbs in this place? If switch controlled could the switch be turned on?-]

There are some incandescents on other cirucuits, the ones from the problem J-box is a fluorescent.

[-Depending on what you are using to "ring out" these circuits-]

A fluke meter sent to Continuity, reads ohms and beeps.

[- a branch circuit supply from the circuit breaker panel could very well show continuity between the "hot" and neutral leads if all the CBs are closed and there is a light bulb in any circuit. The continuity would be from the tester to the branch CB to the panel bus through a second CB to the light bulb to the neutral conductor back to the neutral bus in the panel and finally through the neutral conductor back to the tester. If this is the case then there should be TWO circuit breakers that could interrupt the circuit, the one on the branch circuit you are testing and the one on the branch circuit of the light bulb.-]

Oh I see what you mean. I surmise when you say the CBs are "closed" you mean in the "on" position correct ?

If I read that correctly you have enlightened me and I can now track this down further. BTW I've found that even a fluorescent will still show continuity (with the power off) as long as good bulb is in it. Surprised me but it did.

Now that my confusion is corrected on "how" I was reading continuity with the breakers on with the J-box wires not connected (cept thru my tester). I can now proceed to just connect the J-box pair and go back to the panel, turn off all the breakers and test each wire going in a breaker to the neutral bar for continuity. If I find on that should be the home feed breaker. Correct ?

I will also check out the other data you posted also. You have me on a good direction here. It may be a day or so before I get back over there but I will let you know what I find. And THANKS!
 
 

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