I’ve searched the forums quite a bit and can’t find any other question like this one. I recently moved into a new house and needed to remove a light fixture from a wall in a bathroom. So I needed to turn off the breaker to the fixture, but the previous owners didn’t mark any of the breakers in the panel or sub-panel (which is right next to the main panel). I didn’t have a circuit breaker finder tool, so I had to resort to turning off (and back on) each breaker sequentially while someone waited at the light and told me when it went off. After going through almost all of the breakers, I eventually found the right one and turned it off. This turned off that fixture as well as a number of other lights in the bathroom. Then I removed the fixture, capped the wire, put it in the wall, and turned the breaker back on. All of the other lights that had been turned off (because of the off circuit) all came back on as expected. Everything seemed normal until I noticed that the lights and plugs in two other rooms in a different part of the house didn’t work. Note that the other lights on the circuit with the light I removed were all working, so I know the non-working lights/plugs are on a different circuit. I suspected that one (or more) of the other breakers that I had turned off and on must not have switched completely back on (I didn’t know which one, since they aren’t labeled). So I went through all of them and made sure they were all in the on position (they were). But still the other lights/plugs didn’t work. So I went through all of them again and turned them off and back on, but still no luck.
Next I thought it might be possible that a GFCI had tripped (or gone bad), although it would be strange to have two entire rooms wired after a GFCI. But despite extensive searching I couldn’t find any GFCIs that weren’t working. It’s possible that there is a GFCI hiding somewhere I haven’t found, but I don’t think that’s the problem.
At this point I suspected that one of my breakers had gone bad (triggered by my initially switching it off and back on). So I took off the covers to my panel and sub panel and used my multimeter to check the voltage between each breaker load screw and the neutral. I went though all 48 breakers and found two 15A breakers in the sub-panel that weren’t showing any voltage (the others were all 120V as expected). So I thought that those two must have both died, so I went to the store and bout two new ones and replaced the bad ones. But still no voltage coming from those breakers, and no lights/plugs. I did a continuity check on the “bad” breakers that I had taken out and found that they were actually both still good.
So that’s the situation I’m in. Also, in the course of doing this diagnosis I bought a circuit breaker finder tool and was able to label just about all of the other breakers, however I can’t use the tool on the dead plugs/lights since the tool requires the circuit to be energized. None the less I’m pretty confident the breakers for the dead lights/plugs are the two that I’ve identified as not having any voltage. My question is, what can cause a breaker to show no voltage between the breaker and the neutral, assuming the breaker is good and properly installed? Is there something in the house wiring that can cause this? Is there other testing that I can do to diagnosis where the problem is? Thanks in advance for any help.