Wiring a 50 amp circuit

Separate circuit--if you use both appliances at once you'll overload. As for ga--check codes.

Consult with a licensed electrician.

I to suggest you have a license electrician do the work for one there is the issue of the insurance company laughing at you if you had a electric fire with unapproved non-code wiring in the home and 50 amps at 220 volts is 11,000 watts or enough power to light up 110 hundred watts bulbs. so you need to had the job done correctly.

probably a little late now, but im a lic elec. the others r correct u HAVE to run a dedicated cir to it. #8 will work on the 40a but 50a will require #6 thhn/thwn. id pull the #6 to allow for voltage drop and just in case u or future owners get another cooktop that calls for 50 or 60a down the road. pullin it sux but trust me pullin it out will suk more and cost a lot more. i recommend still not tryin urself