BobH <bob.huc...@gmail.com>

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