[don911]

I'm doing a kitchen remodel and am hooking up some existing 220 to a cooktop and wall oven.
I have existing 10 gage copper wire and 6 gage AL wire. My cooktop needs 40 amps and my oven 30amps. According to my wiring book, my cooktop will need 8 gage wire and oven will need 10.

My plan is to use the existing 10 gage copper and run it to the oven. Should be fine.

For the cooktop, I plan to run new 8 gage copper from the cooktop up to a junction box and mate with the existing 6 gage AL. I've seen some scary pics of heat generated from bad AL/copper connections. I plan to use the proper AL/copper lugs for the connection but am wondering about the gage change from 8 to 6.
Any thoughts on possible issues going from 8 gage copper to 6 gage AL?

Also, I would have expected the oven to have higher amps than the cooktop. Seems odd that the oven can use smaller wiring. Normal?