Troubleshooting a fault

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nizak

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I am trying to troubleshoot a residential branch circuit and am getting nowhere. I have breaker that won't stay set. I have determined that the hot conductor is grounded somewhere downstream from the panel. I have taken apart the devices that I know to be on the circuit(includes finished basement, living room, part of a bedroom) and nothing seems to clear it. The house was built in the 50's and is a mix of grounded and ungrounded NM cable. The circuit in question is 3 wire where it leaves the panel but am finding 2 and 3 wire mix in various boxes and lighting outlets that I've taken apart.The basement has a finished ceiling and I suspect there are some buried J-boxes thru out it. The problem arose out of the blue, everything was working fine and then nothing. It's a mixed bag of workmanship, one of the lighting outlets appears to have been oprerating with a switched neutral as opposed to a switched hot conductor. I am dealing with metal boxes, some are grounded some are not some have as many as double the alloiweable wire fill. Am I overlooking something simple? Any thoughts appreciated.
 
Nizak...

Just went thru such a scenario!

Problem was in a light switch hidden behind an art-painting on the wall! The home owner had forgotten it was there!

Regards, Phil Corso
 
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I am assuming you have already took the wire off the breaker to verify its not defective, so so the next step would be "If I was an idiot electrician,(or carpenter) how would I run it:lol:" . Find the nearest receptacle or light that is not working and break everything apart there. Since this was an apparent rewire, try to find the first point the new wiring was connected, if you cannot, your probably looking at a j box buried in a wall :rant:. A good tool for finding faults like this is a good circuit tracer. Remove the wire from the breaker, put a battery between it and the ground, start scanning the walls and ceiling, if it appears to dead end in the middle of a wall, that maybe where the buried splice is. If it appears to dead end in an outlet or light, you have found where the short is. Be sure to have all of the light switches off and all loads unplugged from the outlets.
 
You have most likely already done so, but I have found a valuable tool is to make sure and ask what task has been performed lately at the residence, no matter how menial. A few times I have found that "added shelf" or "new picture hung" or added plumbing to provide a good clue.
 
Can only physically see the NM cable 2' from the panel. It disappears into a finished ceiling in the basement. I told the homeowner that I would most likely be removing the 12"x12" fiber tile from the ceiling to see where the first point of junction is located. The kicker is that this circuit is feeding outlets scattered at random thru-out the house. Just got to thinking that there is an exterior light (switch controlled) that I did not take apart that's on that circuit, owner did say that she wasn't sure if it ever worked but the switch to it is off.BTW, I have not opened a box yet that had more than 2-3" of conductor length and I', measuring that from where it enters the box!. I did break one connection in a recep the furthest from the panel and lost the continuity at that point between the neutral and hot conductors but still had it at the panel.
 
You mention that this is an older home.You will find most HR and feeds on the ceiling juntion boxs. I would take apart all thoes first that are not working.New houses you would bring all your HR and feeds into two gang 3 gang mounted on the wall.
 
Circuit tracer?

Have you strung out some romex and scabbed into the circuit at various points straight off the breaker to see what you can energize without tripping the breaker?
 
nizak said:
Can only physically see the NM cable 2' from the panel. It disappears into a finished ceiling in the basement. I told the homeowner that I would most likely be removing the 12"x12" fiber tile from the ceiling to see where the first point of junction is located. The kicker is that this circuit is feeding outlets scattered at random thru-out the house. Just got to thinking that there is an exterior light (switch controlled) that I did not take apart that's on that circuit, owner did say that she wasn't sure if it ever worked but the switch to it is off.BTW, I have not opened a box yet that had more than 2-3" of conductor length and I', measuring that from where it enters the box!. I did break one connection in a recep the furthest from the panel and lost the continuity at that point between the neutral and hot conductors but still had it at the panel.
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Ut-oh! My worst fears! There is probably a buried j-box in that ceiling. Friday I stopped by our comptroller's brother in laws house, he wanted to free up space or add another panel in order to power a new mini split he was putting in his basement. The panel was a 24/40 200 amp, and it had 24 standard breakers in. No big deal, put in 4-ctl tandems. He had the ceiling and walls tore out due to mold, and was replacing them. He had run new wire and switches, and wanted to know if he could just cover up the old still connected j-boxes with the new Sheetrock!:roll: I told him he would have to take the wiring back to the nearest accessible point. But then I saw a j box that looked like everything in the basement passed thru it! Told him the best thing he could do there is leave it where it was at and put a blank decorator cover on it.
 
Cow, I did tap into the circuit at 2 random points and still had the fault. What are the chances of a recep going bad and grounding out the circuit? I do have a few points where there were single feeds coming into wall receps from the basement and I did not disconnect the wires. I have run into receps that have grounded out but they were obvious to see just by looking at them whether it be due to a burned up device or excessive corrosion due to wet conditions over time.
 
I would series the breaker through a 50w light bulb then start opening boxes. When the lamp goes out, or starts burning dim you have located the fault or at least the a spot to start looking closer.

If you need to get the light closer out somewhere easy to see use some romex or an old extension to get the light bulb to the room you are working in.
 
I don't have a circuit tracer to use. Use your Volt Con or Wiggy to check for continuity. Not exactly kosher but for testing purposes

use an extension cord to tempoarily power up parts of the circuit. If you don't have power to the first box after the panel, well

their is your problem. Between the panel & first box. But you already knew this, so I guess I don't understand your problem.
 
nizak said:
Already to that point, lamp just keeps glowing at 60 watts!
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If you have taken apart about everything you can on the circuit in question and the lamp never changed any, then the fault must be on/near the home run portion of the circuit.

Also make sure you do not have a second circuit inadvertently tied into this one - you do lose voltage when the breaker is off don't you?

Last time I had something similar to this I went to lighting outlet nearest the breaker first, found that circuit split multiple directions from there and used a meter to determine which of the splits had the fault and reconnected everything else and turned the circuit back on. Whatever portions of the circuit that now operated were no longer part of the search of the problem. On that particular installation I eventually found that the supply lead of a ceiling fan was against the fan rotor and eventually rubbed through the insulation.
 
Well I finally found the problem and could not believe what it was. I was told by the HO which receps and lighting outlets were not working thru out the house so like an idiot I focused my attention on those. After dropping 2 basement ceiling florescents(4"x1.5" octagons w/bar hanger stud in center and 10 conductors each 2" long) opening and disconnecting 10 wall receps, and removing 1 ceiling fan I found the problem in their teenage daughters bedroom which I was told everything was working in. There I find a lamp on a dresser plugged in and I get a warm fuzzy feeling immediatetly. Look at the lamp and was dumbfounded by what I saw. The hot and neutral wires in the cord were both wrapped around one screw on the lampholder/switch assembly. The other screw was tightened to a point that there was never a lead attached to it. I showed it to the HO and she said that she remembers buying it a garage sale and that it worked. There is no way it ever worked in the condition I found it in, somebody is jerking my chain and not fessing up to screrwing with it. I feel bad about charging $450.00 but on the other hand seeing the 2 cartons of Camel's, a pile of $5 scratch off's and her watching Dr. Phil for the most part of the 6 hrs I was there made it easier.
 
nizak said:
Well I finally found the problem and could not believe what it was. I was told by the HO which receps and lighting outlets were not working thru out the house so like an idiot I focused my attention on those. After dropping 2 basement ceiling florescents(4"x1.5" octagons w/bar hanger stud in center and 10 conductors each 2" long) opening and disconnecting 10 wall receps, and removing 1 ceiling fan I found the problem in their teenage daughters bedroom which I was told everything was working in. There I find a lamp on a dresser plugged in and I get a warm fuzzy feeling immediatetly. Look at the lamp and was dumbfounded by what I saw. The hot and neutral wires in the cord were both wrapped around one screw on the lampholder/switch assembly. The other screw was tightened to a point that there was never a lead attached to it. I showed it to the HO and she said that she remembers buying it a garage sale and that it worked. There is no way it ever worked in the condition I found it in, somebody is jerking my chain and not fessing up to screrwing with it. I feel bad about charging $450.00 but on the other hand seeing the 2 cartons of Camel's, a pile of $5 scratch off's and her watching Dr. Phil for the most part of the 6 hrs I was there made it easier.
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"...when you have eliminated the impossible, whatever remains, however improbable, must be the truth."

--- S. Holmes
 
Sometimes I feel a little guilty about how long some of these snipe hunts take too. If I miss something obvious that I should of seen I'll knock my time down a little and remember not to do it next time. But otherwise, it's not your fault their house has problems, it costs what it costs to find it.
 
Good that you found it, sometimes its best to make sure everything in the house is unplugged that wont work when you try it, also any switch that obviously doesn't do anything gets turned off, or in the case of a 3-way gets put in the middle so it can't make contact, my second thing I look for is any outside underground feeds even if the homeowner tells you "oh that thing hasn't worked in years" it could be still fed and it gets disconnected if you can find where it is fed from, also never over look an attic, as there can be a ventilator fan up there that the motor has grounded out, same with crawl spaces.

For everything else it is divide and conquer.

Of course a good circuit tracer makes the job a heck of allot easier and is worth the investment
 
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