I am remodeling my kitchen and have a new wall oven and a new cooktop. In the wall, there are separate junction boxes containing 240-volt aluminum wires for the oven and the cooktop. Each junction box has four aluminum wires -- two black, one black with a barely recognizable white strip and a bare wire. The bare wire is connected to a lug screwed to the metal box.
My question is how to wire the two appliances. The oven comes with a four-wire copper cable. I suppose the bare wire from the oven should go to the bare ground wire, white should go to the white-striped neutral wire and black and red should go to the two black wires. Are the two black wires in the wall interchangeable? If not, how do I know which one goes to the red from the oven? Why are there four wires in the first place?
The cooktop, on the other hand, has only three wires -- red, black and bare copper. Why no white? How should I match up the three cooktop wires with the four wires in the wall.
I realize I need to use antioxidant in the wire nuts when connecting aluminum to copper. Any other precautions needed?
--Bob