Wire short behind finished drywall

All, I am in the US (Ohio specifically) and am running into an issue with a dead short on 12/2 romex feeding my disposal and dishwasher. I have isolated the line and disconnected any appliances as well as disconnected from the breaker, but the neutral and hot are solidly in contact somewhere. I am under the impression that this is the only thing ran on the circuit and I've checked every other outlet in and out of the house and they all work. I can't follow the faulty wire from the panel in basement, because it immediately goes into the wall above (away from kitchen oddly enough) and I can't follow from the kitchen because of finished drywall on the basement ceiling (if it comes from below). I've not changed anything in the house (new roof though, problems started 2 days later), no rodent activity, no rain, but something changed. The wire in question runs into the wall from the panel bundled with at least 6 others. It does not seem to to be GFCI protected anywhere, house built in 2000.

I can open up the drywall, replace the wire, etc. I'd like to do this as a last resort. Am I missing something? Any other likely causes or typical routes a circuit like this would take? Other troubleshooting ?

 

Well I would sure have a peek up in the attic since you had roof work done. I'm also in Ohio and 90% of my wiring is up in the attic. Runs from the panel in the basement, up to the attic, and then across to wherever. It's not supposed to be close enough to the roof that an errant nail could hit it, but it often is. I'd pay special attention to where wires might enter a hole in the top plate of an exterior wall, since that is where it is likely to be closest to the roof.

A fox and hound tracer would let you figure out the general path the cable is running to narrow the search.

 

Thanks, that sounds like a good idea. Unfortunately, where the wires go up the wall from the panel it is in a room with vaulted ceiling, so limited access. Easy enough to see what I can see where I do have access though.

 

Yes, but do it in the morning....attics around here get toasty on days like we've been having!

 

Sometimes wire is punctured by screw or nail, but not shorted and go unnoticed for many years. One day, there may be a slight movement and expansion and finally a short occurs.

So, it could been damaged by cabinet mounting screws.

 

If this is the only thing on the circuit you can disconnect the wires from the breaker and panel to start with. Then do continuity tests on each segment of the circuit. If you get continuity from the black to the white or black to ground in a segment of the circuit then that is where the short is.

Example: if jbox in attic going down to receptacle box for receptacles for dishw and disp, Disconnect wires in jbox in attic and receptacle box. test your continuity at either box. if continuity then that is where your short is, between the jbox in the attic and recptl box. If no continuity there then test from the jbox in the attic to the next point of connection until you work your way back to the panel. Somewhere there has to be continuity if you are getting a dead short in the circuit. That is unless when you put the receptacle in the box for the dishw and disp your ground wire was touching a hot wire. look at the receptacle to see if there is any signs of sparking/shorting.

 

Unfortunately there are no boxes or junctions between panel and kitchen wall that I can find. Nothing is running through the attic other than a few wires for overhead lighting or outside bathroom walls. I've already tracked the short away from the disposal/dishwasher, so it seems as though it exists in the run from the panel. I had one more thought last night. The last part of the roof they did before the problem was a small bumpout right where the kitchen sink is - very similar to this image - imagine the wire running down right next to the window. If any wires were close to the surface, this would be it. Maybe I can get under the soffit and see

 

Do it quickly. If you can show it was their work (the contractor) that shorted out the circuit it is then their responsibility to fix it.

I went on a few calls where the previous contractor caused some damage to a circuit - one even being the main electrical service entrance and I fixed it while it was hot (bugged it) in the rain; made some nice bucks that day. Home owner got his money back from the contractor.. The home owner had a disabled person in the house and needed "juice" to the house ASAP!!!! I knew the home owners would get his money back anyway though. In theory, made money on that one but back in 2012 a woman called me on Easter Sunday at 9pm at night. Said she had no heat because her furnace was not working. I dropped what I was doing and ran over to her house. Single mom of 3 young children. I fixed the problem in the circuit and got the furnace going in 15 minutes. She asked me "how much do I owe you", my reply was "nothing - Happy Easter". She forced a $20 bill in my pocket anyway for gas money to drive there.