I'm redoing our kitchen and am bringing our electrical up to code. Originally the microwave was tapped off a bathroom circuit which also feeds the lights in the kitchen which is all on a 15A circuit. The 6 receptacles were split between 2 20A circuits.
I have split up the receptacles so there are now 3 20A circuits with GFCI receptacles except the fridge receptacle which is just a standard receptacle. I pulled a new 20A circuit to the microwave as well.
I have a couple questions about the old bathroom circuit. I wanted to keep the existing bathroom circuit wiring that feeds the lights in the kitchen. To do this I need to keep a junction box in the wall but this will wind up being behind the microwave once it's mounted above the stove. Do I need move this box or get rid of it and run a new circuit for the lights in the kitchen?
To bring up to current code the bathroom power should not feed anything else. A bathroom circuit can feed outlest in that bathroom & other bathrooms, or it can feed everything in the bathroom
If the microwave is fixed in a place then I think you need to run a new circuit. A junction box must be readily accessible, that means you do not need any tools to access the box (except to unscrew the cover)
You are required by code to have 2 20a kitchen countertop circuits
Since you have (3) you could use power from the 3rd "extra" circuit for the lights.
Or tap into another circuity that is not used much