LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
I had an interesting troubleshoot yesterday that I have to return to finish. The kitchen/living-room/foyer lighting circuit has a short circuit that suddenly began a couple of days ago. I checked every switch box involved, making sure every switch was switched off, and found nothing. I placed a receptacle in series with the breaker and black wire, and plugged in the customer's shop vacuum as an audible test. The vacuum runs at full speed, with no variation, confirming a direct short.
Nothing I did caused any change to the vacuum, so I then disconnected the white and bare conductors of that circuit's NM cable from the panel's neutral bus, and the vacuum still runs at full speed. This tells me the black wire is grounded externally from the circuit's conductors. The only box where another circuit is involved is the sink light/disposer switches, which I opened and pulled the switches out. Still no change. I figure the next step is to visually trace the circuit in the crawl.
To me, disconnecting the neutral and EGC in the panel eliminates a staple, nail, or screw through the cable. I plan to return tomorrow with my helper to try the visual trace. I hope to minimize the time and cost to the customer any more than necessary to restore the power. Can anyone suggest a possibility other than the black wire being faulted to something solidly grounded under the house (or worse, inside a wall) that can cause this set of symptoms?
Nothing I did caused any change to the vacuum, so I then disconnected the white and bare conductors of that circuit's NM cable from the panel's neutral bus, and the vacuum still runs at full speed. This tells me the black wire is grounded externally from the circuit's conductors. The only box where another circuit is involved is the sink light/disposer switches, which I opened and pulled the switches out. Still no change. I figure the next step is to visually trace the circuit in the crawl.
To me, disconnecting the neutral and EGC in the panel eliminates a staple, nail, or screw through the cable. I plan to return tomorrow with my helper to try the visual trace. I hope to minimize the time and cost to the customer any more than necessary to restore the power. Can anyone suggest a possibility other than the black wire being faulted to something solidly grounded under the house (or worse, inside a wall) that can cause this set of symptoms?