In my home, in one bedroom circuit, there are several receptacles. After first two receptacles, next socket has no power. After significant effort, it has been determined that the sockets are fine, connections are okay, but one wire coming from attic via the wall is broken. However, I do have a 100% confirmation. Questions: (1) How can I be 100% sure of this diagnosis. (2) Assuming that my diagnosis is correct, how to replace existing discontinuous (broken) wire with a new one through the wall. Earlier answers did not answer either of these questions. M.S.
To confirm the wire is broken/damaged, you can measure the electrical resistance of the cable with a multi-meter. If the wire is OK, you should get a near-zero measurement. If it is broken or significantly damaged, the resistance will be a high value or infinity.
You need to isolate the section of cable you think is damaged to in between two electrical boxes. With the power off, at one end of the cable, connect the hot and neutral with a wirenut. Measure the resistance between the two at the other end. Repeat this with all combinations of hot/neutral, hot/ground, neutral/ground in order to figure out which wire is broken.
As far as replacing the cable, you will likely need to cut one or more holes in your wall in order to pull a new cable through. If it's a relatively straight and short run you might get away just removing the electrical boxes and fishing a new cable through, and then replacing the electrical boxes, but usually you have to cut multiple holes to run a new cable.
I will all but guaranty the wire, in the section between boxes, is FINE. It is a very common misconception that wiring somehow goes bad in the middle of a run. It is extremely rare that it does. The almost certain point of failure is a splice or connection point, such as at a receptacle.
Let me ask, how did you determine the devices are OK? Are there any backstabs (quickwire connections) in the backs of any receptacles? Did you completely remove all receptacles and replace them back in the boxes using the side screws?
Can you confirm the 2 splice/connection points between what you think is the bad cable section?