Background: I'm doing some rewiring work in the kitchen. There were three circuits coming into a junction box that controlled the sink disposal, dishwasher, a few receptacles and a light. So I got everything the way I want, and the dishwasher circuit seems like it's dead. First thought is bad wiring, so I rechecked everything - no issues. Next thought, there's a GFCI upstream that I tripped while I was working (I've wasted a few hours on that problem before). But an ohmmeter check on the common/ground says no GFCI tripped. So I recalibrated my voltmeter and tested the line again and lo and behold, there is some power, but only about 20V.
Question: could the breaker really have gone bad while I was working on the junction box? Everything I know says it's possible but extraordinarily unlikely. I've even replaced a breaker before thinking it had gone bad, and it turned out not to be the problem after all. So before I do it again, is there anything else I'm missing?