We have 2 small appliance circuits in our kitchen. They are carried over the same physical cable, one circuit is on black, the other on red. The black circuit works fine. The red does not. Its rather annoying since that represents half the outlets in our kitchen, including the one that our microwave should plug into, so we are forced to put it on the countertop. I found what I think is the first outlet in the chain (it is a GFCI). First, I tried replacing the GFI outlet, nothing changed. Next, I took the longest electrical wire I had and used it to extend the lead of my multimeter, and checked for continuity between the red wire on the breaker, and the red wire at the outlet, no continuity. I swapped the red and black wires on their respective breakers just making sure it was not some kind of weird problem at the breaker. The black wire worked fine on the red wire's original breaker, and the red wire continued to not work. SO I put them back. Then I just gave up for a while. I went to Harbor Freight yesterday and bought a wire tracer (tone generator and probe). When I connect the tracer to the red wire at the outlet the tone immediately gets very, very quiet, enough that I would say its "dead". I cannot trace it, because after I'm a few inches away, there is nothing but noise. Take it off, the tone comes back. If I attach it to the other red wire at the outlet (the outgoing) I can pick up the tone in the wall to some degree, and pick it up at the downstream outlets no problem. Why would the signal die on my red wire? What does that mean? Do I need to disconnect it from the breaker? Any other advice or suggestions for how to figure this out?
From the information that you gave so far it would seem pretty conclusive that the red wire has broken open between your test outlet box and the power panel.
Did the red wire circuit outlets ever work?
If they did work at one time can you think of any key events that may have occurred between them working and not working? Think about things like installation of any thing that required drilling, nailing or screwing into wall or ceilings anywhere. Were there any key plumbing problems that required repair where adjacent wiring may have been disturbed? Also do not discount any possibilities that work was done on an attic space or crawlspace where any romex type wiring may have been stressed or pulled on.
Any of the above could be clues as to what may have happened to open up the red wire circuit.
Beyond that there is always the possibility that there is another junction box between the breaker panel and the outlet box that you have been testing in. There could be a connection within such electrical box that has come open and disrupted the red wire circuit.