The breaker for my microwave tripped and when I turned the breaker back on it tripped again after using the microwave again. I tested the microwave in another outlet and it works fine. I went to replace the outlet and I found a black wire, two white on the same side, and ground. I turned off the breaker and tested the wires only to find that one white wire still has 120v where all other wires are dead. Why is that wire supplying voltage on the neutral side?
You could be dealing with 1/2 switched receptacles. 1 part of the receptacle is controlled by a wall switch that will allow table lamps and etc to controlled by that wall switch. My whole house is wired that way. Half the receptacle is wired always hot and the other is controlled by a switch. Check it out.